the case of 8 parishes (West Kilbride, Largs, Barr, Lochwinnoch, Paisley, Avondale, East Kilbride,. Tarbolton) less than 10% of the parish area was located in the ...
IMPACT OF AGRICULTURAL PRACTICES AND CATCHMENT CHARACTERISTICS ON AYRSHIRE BATHING WATERS
Mark Aitken, David W Merrilees and A Duncan Environment Division SAC, Auchincruive
Scottish Executive Central Research Unit 2001
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Further copies of this report are available priced £5.00. Cheques should be made payable to The Stationery Office and addressed to: The Stationery Office 71 Lothian Road Edinburgh EH3 9AZ Order line and General Enquiries 0870 606 5566
The views expressed in this report are those of the researchers and do not necessarily represent those of the Department or Scottish Ministers.
© Crown Copyright 2001 Limited extracts from the text may be produced provided the source is acknowledged. For more extensive reproduction, please write to the Chief Research Officer at the Central Research Unit, Saughton House, Broomhouse Drive, Edinburgh EH11 3XA.
CONTENTS LIST OF TABLES LIST OF APPENDICES ACKNOWLEGMENTS EXECUTIVE SUMMARY ..........................................................................................................................................1 CHAPTER ONE INTRODUCTION ........................................................................................................................4 CHAPTER TWO PROJECT OBJECTIVES..........................................................................................................6 CHAPTER THREE PROJECT METHODOLOGY .............................................................................................7 CHAPTER FOUR CHARACTERISATION OF THE RIVER IRVINE AND WATER OF GIRVAN CATCHMENTS..........................................................................................................................................................13 SOIL TYPE .................................................................................................................................................................13 LAND-USE AND FARMING TYPES................................................................................................................................14 STOCKING DENSITIES IN EACH CATCHMENT ..............................................................................................................16 FARM WASTE PRODUCTION DURING HOUSING AND GRAZING....................................................................................19 CLIMATIC DATA ........................................................................................................................................................24 TOPOGRAPHY AND LANDFORM ..................................................................................................................................25 HYDROLOGY - THE HOST CLASSIFICATION SYSTEM ................................................................................................26 LAND SUITABILITY OF CATCHMENT FOR MANURE APPLICATION BASED ON A RISK ASSESSMENT AND GIS ...............27 CHAPTER FIVE RESULTS OF THE FARMER SURVEY...............................................................................28 RIVER IRVINE CATCHMENT........................................................................................................................................28 WATER OF GIRVAN CATCHMENT ...............................................................................................................................39 RISKS OF FAECAL CONTAMINATION TO WATERCOURSES AND BATHING WATERS .....................................................50 NO. OF FARMS (TOTAL = 20).....................................................................................................................................51 CONTRACTORS SURVEY.............................................................................................................................................56 CHAPTER SIX CONCLUSIONS AND RECOMMENDATIONS.....................................................................62 REFERENCES............................................................................................................................................................65
LIST OF TABLES Table 4.1 Table 4.2 Table 4.3 Table 4.4 Table 4.5 Table 4.6 Table 4.7
Parishes with a high proportion of land area within the catchments ...............................15 Land-use of main parishes in River Irvine catchment.....................................................16 Land-use of main parishes in Water of Girvan catchment..............................................16 Total numbers of each livestock in the main parishes of each catchment parishes..........18 Stocking density (number per ha) of the main parishes in each catchment.....................18 Stocking density (number per ha) adjusted for grazing area...........................................18 The total amount of farm waste produced during the housing and grazing period for each catchment .........................................................................................................20 Table 4.8 Production of wastes during animal storage for each parish (6 months) ........................21 Table 4.9 Wastes produced during grazing (6 months) for each parish .........................................22 Table 4.10 Amount of waste produced by storage and grazing in each part of parish within the catchment..................................................................................................................23 Table 4.11 Long term average climate in the main agricultural areas of Ayrshire bounded by the sea.............................................................................................................................25 Table 4.12 Agro-climatic data for lowland Ayrshire....................................................................25 Table 4.13 Percentage of land area in each slope class ................................................................26 Table 5.1 The percentage of dairy farms in the River Irvine catchment with each storage system, average volume and functionality..............................................................................32 Table 5.2 The percentage of beef farms in the River Irvine catchment with each storage system, average volume and functionality..............................................................................32 Table 5.3 The percentage of dairy farms the River Irvine catchment which have access to different types of spreader systems..........................................................................................35 Table 5.4 The percentage of beef farms in the River Irvine catchment which have access to different types of spreader systems ...........................................................................35 Table 5.5 The percentage of farmers in the River Irvine catchment who took certain factors into consideration in deciding if a field was suitable for a manure application..................36 Table 5.6 Type of land receiving farm manures in the River Irvine catchment...............................37 Table 5.7 Time of application of farm waste for dairy farmers in the River Irvine catchment........38 Table 5.8 The percentage of beef farmers in the River Irvine catchment who apply farm waste on each of the months of the year ..................................................................................38 Table 5.9 The percentage of dairy farms in the River Irvine catchment applying some or all of their farm waste to each land use category........................................................................39 Table 5.10 The percentage of beef farms in the River Irvine catchment applying some or all of their farm waste to each land use category ...............................................................39 Table 5.11 Storage of farm manures on dairy farms in the Water of Girvan catchment...............42 Table 5.12 Storage of farm manures on beef farms in the Water of Girvan catchment................42 Table 5.13 The percentage of dairy farms in the Water of Girvan catchment which have access to different types of spreader systems ...........................................................................43 Table 5.14 The percentage of beef farms in the Water of Girvan catchment which have access to different types of spreader systems ...........................................................................43 Table 5.15 The percentage of farmers in the Water of Girvan catchment who took certain factors into consideration to decide if a field was suitable for a manure application .............44 Table 5.16 Type of land receiving farm wastes in the Water of Girvan catchment ......................45 Table 5.17 The percentage of dairy farmers in the Water of Girvan catchment who apply some or all of their farm waste on each month of the year......................................................46
Table 5.18 The percentage of beef farmers in the Water of Girvan catchment who apply some or all of their farm waste on each month of the year......................................................46 Table 5.19 The percentage of dairy farms in the Water of Girvan catchment applying some or all of their farm waste to each land use category ...........................................................46 Table 5.20 The percentage of beef farms in the Water of Girvan catchment applying some or all of their farm waste to each land use category is given in the table below..................47 Table 5.21 The percentage of farms in the River Irvine catchment using various sources of water, averaged across the livestock enterprises..................................................................48 Table 5.22 The percentage of farmers in the River Irvine catchment using various watering systems in their grazing fields, averaged across the livestock enterprises..................48 Table 5.23 The percentage of farms in the Water of Girvan catchment using various sources of water, averaged across the livestock enterprises.......................................................49 Table 5.24 The percentage of farmers in the Water of Girvan catchment using various watering systems in their grazing fields, averaged across the livestock enterprises..................49 Table 5.25 A summary of the main operational and system factors, relevant PEPFAA section, risks to watercourses and remedial guidance ............................................................52 Table 5.26 Factors considered during field risk assessment.........................................................57 Table 5.27 Application equipment and handling rates..................................................................58 Table 5.28 Annual application of slurry by contractors in the Irvine and Girvan catchments.......59 Table 5.29 Annual application of FYM by contractors in the Irvine and Girvan catchments.......59 Table 5.30 Seasonal spreading of manures in the Irvine and Girvan catchments .........................60
LIST OF APPENDICES 1.
Letter to all farmers in River Irvine and Water of Girvan Catchments
2.
Letter to all farm waste contractors operating in River Irvine and Water of Girvan Catchments
3.
Questionnaire to all farmers
4.
Questionnaire to all farm waste contractors
5.
Land suitability for waste application
6.
Map showing parishes, main towns and rivers of River Irvine catchment.
7.
Map showing parishes, main towns and rivers of Water of Girvan catchment.
8.
Map showing dairy cattle intensity of River Irvine catchment.
9.
Map showing dairy cattle intensity of Water of Girvan catchment.
10.
Map showing beef cattle intensity of River Irvine catchment.
11.
Map showing beef cattle intensity of Water of Girvan catchment.
12.
Map showing sheep intensity of River Irvine catchment.
13.
Map showing sheep intensity of Water of Girvan catchment.
14.
Map showing main soil types of River Irvine catchment.
15.
Map showing main soil types of Water of Girvan catchment.
16.
Map showing rainfall intensity of River Irvine catchment.
17.
Map showing rainfall intensity of Water of Girvan catchment.
18.
Hydrology of Soil Types (HOST) in the River Irvine Catchment.
19.
Hydrology of Soil Types (HOST) in the Water of Girvan Catchment.
20.
Map showing elevation of River Irvine catchment.
21.
Map showing elevation of Water of Girvan catchment.
22.
Map showing slopes of River Irvine catchment.
23.
Map showing slopes of Water of Girvan catchment.
24.
Map showing land use cover of River Irvine catchment.
25.
Map showing land use cover of Water of Girvan catchment.
26.
Agricultural census data for each parish in the River Irvine and Water of Girvan catchments.
27.
Datasets used in assessing unsuitable land in River Irvine catchment.
28.
Datasets used in assessing unsuitable land in the Water of Girvan catchment.
29.
Geographical risk assessment in the River Irvine catchment.
30.
Geographical risk assessment in the Water of Girvan catchment.
31.
Predicting Faecal Pollution Loadings from Agricultural Activities using a Geographical Information System–based Model
32.
Relevant Legislation
33.
Glossary of Terms and Abbreviations
ACKNOWLEDGEMENTS SAC acknowledge the following organisations for providing data for the purposes of this project. SERAD (parish census data), Institute of Hydrology (hydrological and HOST data), MLURI (land cover and HOST data) and SEPA (climatic and farm data). We also thank NFUS for their vital support and assistance with this project. We acknowledge all members of the project steering group for their valuable input and constructive comments on the first draft report (Dr Liam Kelly, Phil Gilmour, Bill Aiken, Rob Morris, Stephen Field and Henry Murdoch). We thank Adrian Jones, Dave Howat, Dr Ivo Svoboda, Stewart Moir, Chris Savage, Andrew Leggate and Bill Davidson for assisting with the farmer survey and providing technical input into this report. In addition Dr Doug Lewis is thanked for devising the graphical model and for preparing Appendix 26. We also particularly thank all 128 farmers and contractors who willingly assisted us with this project. The project was funded by SERAD.
EXECUTIVE SUMMARY 1. Agricultural manures (livestock slurries and farmyard manures) are valuable fertilisers and soil conditioners, but are also potential sources of water pollution by Faecal Indicator Organisms (FIO) if poorly managed. 2. This report reviews current farm waste management practices, land application of wastes and the land characteristics in the River Irvine and Water of Girvan catchments. It assesses potential impact of these practices on water quality particularly during the bathing season. 19% of farms in the River Irvine and 18% in the Water of Girvan catchments were assessed and all major agricultural contractors interviewed (128 farmers and contractors in total). 3. Predominant agriculture in both catchments is milk, beef and sheep production. The main agricultural land use is improved grassland (70% and 44% of the River Irvine and Water of Girvan catchment areas respectively) and rough grazing (21% and 50% of each area). The parishes with the highest livestock intensities are Symington, Dreghorn, Kilmaurs and Riccarton which are all within the River Irvine catchment. Over the River Irvine catchment during the bathing season (May to September) average overall grazing intensities are 1.3 dairy cattle, 0.8 beef cattle and 2.0 sheep per hectare (ha). The equivalent figures for the Water of Girvan catchment are 1.3 dairy cattle, 1.0 beef cattle and 2.6 sheep per ha. 4. The total amount of farm waste collected, stored and later landspread from winter housing is 390,000 t (undiluted) in the River Irvine catchment and 61,000 t in the Water of Girvan catchment. The waste produced during the grazing season (April-September) is 437,000 t (Irvine) and 90,000 t (Girvan). During the bathing season (May-September) 24% and 36% of stored slurry and 11 and 21% of 'solid' farmyard manure is spread on farmland in the Water of Girvan and River Irvine catchments respectively. 5. The type and volume of manure storage varied considerably from farm to farm. Functionality of storage and effective storage period also varied, with 19% of farms in the River Irvine catchment and 8% in the Water of Girvan catchment having less than 1 month of slurry storage (winter). 6. Point source discharge of effluent, containing faecal indicator organisms, into watercourses can be predicted from many farms visited. Below ground ('aidle') tanks, associated with older and more traditional drainage systems such as byres, represent a risk of FIO water pollution and were found on 11% of farms visited. 7. Most high level slatted buildings had 'functional' storage below the slats, but the subsequent containment and handling of liquid effluent was variable with a number not contained and therefore resulting in a high pollution risk. 8. The majority (58%) of all farms had middens but nearly half of these had no containment resulting in possible discharge of effluent (slurry) to a watercourse. Furthermore, some material contained in middens was unsuitable for this form of storage, i.e. manures from livestock fed on a silage-based diet with minimal bedding as opposed to traditional solid and stackable farmyard manure (FYM). The other main potential sources of FIO to watercourses were from poorly
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contained byres, self-feed silage aprons, cow tracks and watercourses commonly used by stock for drinking. 9. The majority of farms were found to have both clean and dirty water from roads, aprons and roofs entering waste stores, which increases the volume of slurry to be handled and reduces the effective storage period. Non-containment of the dirty water produced on some farms will result in an FIO pollution risk. 10. Septic tanks were used on practically all farms to treat farmhouse wastes. The majority of designs were old and a high proportion discharged directly to watercourses. The connection of other farm building drainage reduces septic tank effectiveness and increases the potential risk of discharge of faecal material to watercourses. 11. Nearly half of all farmers interviewed were unaware of the PEPFAA Code or its contents. Only 12% of farms had a Farm Waste Management Plan (FWMP). The vast majority of farmers use an exclusion zone, 4-5 m in width, adjacent to watercourses in order to protect water quality. 2-7% of River Irvine catchment dairy and beef farmers respectively and 16% of Water of Girvan catchment farmers apply farm manures to steeply sloping ground. 6-9% of River Irvine catchment dairy and beef farmers and 0-3% of Water of Girvan catchment dairy and beef farmers respectively apply manures to very poorly drained land. Manure application to steep sloping or very poorly drained land is a very high risk situation and likely to result in water pollution. 12. Contractors are used for slurry application on 50% of farms in the River Irvine catchment and 34% of farms in the Water of Girvan catchment. For muck spreading, the respective figures are 9% and 4%. A total slurry volume of 446,000m3 is applied by contractors to c.11,000 ha of land in both catchments. The majority of this slurry is applied from January to April with 16% of the total between May and September in the River Irvine and 6% in the Water of Girvan catchments. Out of a sample of 12 major agricultural contractors, only 25% were aware of the PEPFAA Code and only one was aware of FWMPs. On 42% of farms some form of risk assessment was carried out prior to land spreading, usually by the contractor. The majority do not apply slurry immediately adjacent to watercourses but a number of contractors thought that exclusion zones were not necessary. 13. Diffuse pollution of FIO by surface run-off from fields, and/or the field drainage system from intensively grazed land or land that has received a slurry application is another potential source of FIO to watercourses. The soil can act as a reservoir of pathogens during wet and cool conditions when die-off rates are low. Although bacteria are mainly retained on soil particles, they can be washed out during high rainfall events. 14. A number of potential risks to bathing water quality may be eliminated through improved slurry/dirty water management, forward planning of land spreading activities and improved operational procedures. Where a potential risk to bathing water was identified, the majority of farmers could significantly reduce the risk of water pollution by FIOs through limited expenditure and sound management advice. There is a strong requirement to further promote good agricultural practices and adherence to the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 1991 and the PEPFAA Code in both catchments. On a limited number of farms a substantial investment will be required to remove or remedy a significant risk of pollution from storage facilities. It was clearly apparent that under current economic conditions, money for this form of investment is not available. The main operational techniques which farmers and 2
contractors can use to mitigate the problem of FIO point source or diffuse problem and minimise risks are discussed. 15. A Geographical Information System (GIS) model which contains the key elements of faecal pollution of soils and subsequent transport to watercourses is also proposed. This spatially distributed model will take the commonly available spatial data sets, and provide a useful tool for ranking the potential pollution impacts from livestock and farm waste practices. It will identify the sub-catchment areas, the waste management and livestock operations that contribute disproportionately to bacterial contamination and hence be useful to catchment managers and regulators.
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CHAPTER ONE INTRODUCTION 1.1 This report for a project entitled: "Impact of Agricultural Practices and Catchment Characteristics on Ayrshire Bathing Waters" is submitted to SERAD in accordance with the SAC tender dated 19 January 2000. 1.2 SEPAs 2000 Scottish bathing waters report concluded that 85% of all Scotland’s 60 identified bathing waters passed the mandatory standard for the EC Bathing Water directive (76/160/EEC). The percentage of mandatory passes in 1999 was 88%. These results were significantly better than the results for 1998 and SEPA stated that the improved weather in 1999 compared to 1998 had minimised the risk of bathing waters failing to meet the mandatory standards. 1.3 SEPAs 1998 Scottish bathing waters report concluded that the 1998 results for Scotland’s 23 originally identified bathing waters were the worst for 10 years, with only 12 of the identified waters passing the EC bathing water directive’s mandatory standards. Only three of these complied with the more stringent guideline values. This compares unfavourably with 1997 when 18 bathing waters achieved the mandatory standards and five complied with the guideline values. SEPA stated that the cloudy and wet summer had contributed to the disappointing results via two processes. Firstly, the prolonged cloudy conditions with low sunshine hours resulted in a slow die-off rate of faecal bacteria which are normally killed off by the ultraviolet light present in sunlight. Secondly, the high rainfall during the summer caused more frequent operation of combined sewer overflows from sewage systems and an increase in diffuse sources of pollution from land run-off. The situation with the Ayrshire beaches was particularly unsatisfactory with two of seven in 1996, four of seven in 1997, six of seven in 1998 and three of seven in 1999 failing to meet the EC bathing waters standard. 1.4 Recent studies in Ayrshire (Kay, 1999) using regressional techniques have shown that nonpoint sources of faecal pollution from predominantly pastoral agricultural land may be a major component of river bacterial concentrations. However, quantification of river loadings from different land use, farm management, rural septic tanks and soil types remains at an elementary stage of statistical analysis. Further work at the catchment scale with an emphasis on quantifying the diffuse faecal pollution from agricultural fields where grazing occurs or to which slurry or sewage sludge has been applied will be necessary. This requires the development of a catchment model with a spatially distributed nature able to account for different topographies, land use and soil classifications (Fraser et al., 1998), and which can be driven by climatic variables (Gouda et al., 1999). To develop such a model it is necessary to determine the major factors influencing the fate and transport of microbes through soils and to distil this understanding into a dynamic export coefficient approach to catchment modelling. This approach will incorporate the key catchment characteristics determining microbial transport with associated microbial decay rates. Such catchment modelling may be carried out in a Geographical Information System (GIS) environment using the available spatial data sets combined with a detailed survey of the current farming practices in the Ayrshire catchments to determine faecal loadings to soils. This survey describes the practices and type of farms which pose the greatest risk to the aquatic environment and more especially to bathing water. 1.5 The Scottish Executive (1997) publication entitled "The Prevention of Environmental Pollution from Agricultural Activity (PEPFAA) Code" highlights potential environmental problems 4
associated with agriculture practices and provides a practical guide to farmers in ways of eliminating or minimising problems. The scope of the Code covers air, water and soil pollution. An evaluation of the PEPFAA Code carried out by the Scottish Executive Central Research Unit (1999) concluded that farmers found the PEPFAA Code to be an important and useful source on environmental and pollution matters. 1.6 While farm "wastes" is a convenient term to apply to materials that needs to be "disposed of", it must particularly be questioned whether the term is appropriate to describe animal excreta, which have considerable nutrient value. Where possible the term “manure” is therefore used throughout this report. Agricultural manures (livestock slurries and solid farmyard) are valuable fertilisers and soil conditioners but may also be potential sources of pollution if poorly managed. With increasing economic and environmental pressures on farm businesses, it is essential to maximise the fertiliser value of manure, whilst taking action to prevent or minimise the risk of pollution. 1.7 Livestock manures can be solid, semi-solid or liquid. Solid manure is excluded from the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil (Scotland) Regulations 1991, but any subsequent run-off is defined as slurry, and hence subject to the Regulations. The Control of Pollution Act 1974, as amended by Schedule 23 of the Water Act 1989, makes it an offence to cause or knowingly permit any poisonous, noxious or polluting matter to enter controlled waters: 1.8 The River Irvine and Water of Girvan catchments contains 2% of the total agricultural land area of Scotland and 17% of the total number of dairy cows. Livestock farming in both catchments therefore has considerable socio-economic importance both in Ayrshire and as part of the wider Scottish agricultural economy. A discussion on the techniques of the typical systems of production (housing and feeding regimes etc.) is beyond the scope of this report. Further details on these and related topics are given in SAC (1995) and SAC (1999).
5
CHAPTER TWO PROJECT OBJECTIVES 2.1 The overall objective of the research project is to investigate the impact of agricultural practices and catchment characteristics on Ayrshire bathing waters in order to develop a clear understanding of the detailed processes aimed at reducing diffuse pollution and faecal contamination of water. 2.2
The specific objectives of the Phase 1 study reported here is to: • To investigate in detail the current farming practices in the catchments (River Irvine and Water of Girvan) through visits to farms and agricultural contractors supplemented by using SEPA and CREH data. • To carry out a soil and landscape assessment of the catchments. • To make an assessment of existing waste management practices and operational performances in the catchments. • To assess farmer and contractor knowledge, ownership and compliance with the PEPFAA Code. • To devise a graphical model which contains the key elements which contribute to faecal pollution, reporting on the processes involved and transportation of faecal organisms to bathing waters. This model will be produced from existing data held by SEPA, SERAD, MLURI and CREH and by liaison with farmers and agricultural contractors. SAC will fully take into account the monitoring procedures which have been established by both SEPA and CREH. • To determine the risks posed to the water environment due to current farming practices in the Ayrshire catchments.
6
CHAPTER THREE PROJECT METHODOLOGY 3.1
The methodology of each of the agreed Project Stages was as follows:
Stage 1. Review all available relevant information obtainable from SERAD, SEPA, CREH, MLURI and the Met Office. 3.2 Agricultural information on a parish basis was received from SERAD on 3 March 2000 and this has been reviewed and analysed further. The SEPA Scottish bathing waters reports have been reviewed along with individual SEPA farm information. The CREH report (Wyer et al., 1999) entitled "Faecal Indicator Organisms Sources and Budgets for the Irvine and Girvan Catchments, Ayrshire" has also been utilised by SAC along with relevant SEPA, MLURI and Met Office information.
Stage 2. Inform all 600 farmers and waste contractors in the 2 catchments of the benefits of the project and establish co-operation with a representative portion. 3.3 SAC prepared a letter for all farmers and the waste contractors in full collaboration with the project steering group. A copy of both letters is given in the Appendices 1 and 2. SAC received the names and addresses of all farmers in the 2 catchments from SERAD on 3 March 2000. The letters were sent out to all 617 farmers (528 in River Irvine and 89 in the Water of Girvan catchments) during the period 3-6 March 2000. Although most of the addresses obtained came from SERAD parish data, the list was cross referenced with data from BT (Electronic Yellow Pages) and existing SAC address lists in order to obtain postcodes and/or telephone numbers where these were missing. In the absence of OS grid references within the parish database, postcodes were used to establish which farms were within the catchments. Although the postcode identifies the postal address and not necessarily the location of the farmed area, and is accurate only to within a few hundred metres (depending on the size of the postcode area) a few farms were found to use areas outside the catchments and these were rejected. 3.4 British National Grid references were obtained from the postcode information by reference to Personal Navigator, a PC application which makes available OS Address-Point data and the Royal Mail Postal Address File. Once geo-referenced, addresses were imported into the GIS and the list amended to exclude those addresses outside the catchments. 3.5 In order to ensure adequate coverage of the catchments in the event of a high response being obtained from farmers, the address list was filtered prior to dissemination to surveyors, with addresses being supplied in three tranches each of which represented a random distribution over the surveyor's target area. In the event, all tranches were used in order to achieve the target sampling figure of 120 farms. 3.6 A total of 52 agricultural contractors involved with manure management and operating in either the River Irvine or Water of Girvan were identified in collaboration with SEPA. A letter was sent out to each of these contractors on 7 March 2000.
7
3.7 Further information to farmers and others was disseminated via local newspapers and radio as a result of the Press Releases produced by NFUS, SERAD, SEPA and SAC. In addition, the objectives of the project have been explained to a significant number of farmers who have enquired direct to SAC.
Stage 3. Compile databases on the soils, landscape and hydrology of the area using existing published information supplemented by field survey. The MLURI database data will be leased if necessary. The datasets employed in catchment characterisation were as follows:
GIS system 3.8 Cartography and vector datasets were handled with MapInfo V5. Spatial analysis of raster or grid datasets and their interpolation was accomplished with Vertical Mapper, a MapInfo extension.
Base maps 3.9 OS Strategic 1:250,000 mapping was employed on all printed maps as a backdrop only, and has not been used for data extraction. SAC lease this data for use on an enterprise level. Since data extraction was not employed, the data tiles covering the catchments were imported in their entirety in DXF format into a single MapInfo table field. OS mapping is reproduced by permission of the Controller of Her Majesty's Stationery Office under the Scottish Executive/Ordnance Survey Service Level Agreement (licence number AL 545503) and remains Crown Copyright.
Land cover 3.10 A subset of the MLURI Land Cover of Scotland 1988 (LCS88) vector data was supplied by SEPA, under licence. This subset excluded features of no immediate interest to the project (i.e. line and point features such as hedgerows). The data was supplied in ArcInfo Export format and imported into multiple fields in a single MapInfo table prior to trimming by catchment boundary and combination of regions by the LCS88 feature code field. The maps reproduced in Appendices 24 and 25 show the LCS88 data combined by MLURI Land Cover Category. 3.11 LCS88 data is used as received and its limitations are recognised. It is understood for example that arable, forestry and built-up areas have increased since the areas in question were surveyed, and the data is presented merely as an indication of the current situation.
Meteorological data 3.12 Met Office annual and monthly rainfall data (a raster dataset based on a 1 km grid, giving rainfall in mm based on Met Office numerical models) covering the catchments were supplied by SEPA, under licence. This dataset was converted into lookup tables for use in Excel in order to find 8
rainfall for individual farms from BNG co-ordinates within the original database. Farms were assigned the data on the grid node to the SW of the 1 km cell in which they occur. A vector interpolation of the data (performed after import into the GIS) is shown in Appendices 16 and 17.
Elevation 3.13 SAC lease the OS Panorama data set (a raster Digital Elevation Model containing a height value, accurate to circa 2.5 m rms, for every point on a 50 m grid) for use on an enterprise level. This data was interpolated, using spatial analysis tools native to the GIS employed (Vertical Mapper), to produce a slope data set on a similar 50 m grid basis. Slopes were calculated as degrees and are given in Appendices 22 and 23.
Soil type 3.14 The MLURI/IoH Hydrology of Soil Types (HOST) data (a raster data set based on a 1 km grid, containing the proportion of soil types within each cell) was leased for the duration of the project. This data was manipulated in a PC spreadsheet application (Microsoft Excel) in order to identify the major component within each cell. Further, MLURI published mapping (1:250,000 scale series) was interpreted manually and the results digitised and included in the GIS as vector regions. Maps of the soil types, slope and hydrology (HOST) for both catchments have been prepared and digitised (Appendices 14, 15, 18, 19, 22 and 23).
Livestock 3.15 Livestock distribution maps utilise the SERAD parish data and the SERAD parish boundary vector map. Where parts of parishes fall within the catchment, associated data has been recalculated where appropriate in order to reflect the area proportion of the parish affected.
Stage 4. Carry out a survey of farming types in the catchments using SAC and published information. 3.16 Under a confidentiality agreement, SAC received parish agricultural census information from SERAD on 3 March 2000. This information has been a summarised in Appendices 8-13 and 26.
Stage 5. Target up to 120 farmers (20% of the total in both catchments) for a farm visit and then appraise them of their farming practices and compliance with PEPFAA. Verbal and written advice will be provided to all farmers where this will reduce pollution risks. In collaboration with SEPA, SAC would utilise available SEPA farm information to carry out a 'desk based' study on a percentage of the remaining farms. 3.17 SAC randomly selected 118 representative farmers (covering 120 farms) in both catchments (101 farms in River Irvine catchment and 17 in Water of Girvan catchment). A confidential questionnaire entry for each farmer was completed and entered onto a database. A 9
copy of the farm questionnaire is given in the Appendices. In addition, SAC targeted twelve major agricultural contractors and devised a questionnaire (see Appendices 3 and 4) to determine their manure management practices. All twelve major contractors were visited and interviewed.
Survey: data analysis 3.18 Microsoft Excel was used exclusively for data analysis. Unless otherwise stated, the geometric mean is presented for questions returning non-binary responses (e.g. area, percentage, quantity etc.). The mean percentage was rounded up to a whole number resulting in a number of cases of the total percentage not adding up to 100% (normally ±1%). 3.19 Binary responses in the form of answers to "yes" or "no" questions were calculated by using the formula "count yes"/ "total count". In some cases, "total count" refers not to the whole sample but to the number of farms of a certain type, e.g. "dairy" farms. In these cases, selection criteria were applied in order to discount farms with disproportionately small numbers of one type of stock in relation to others (e.g. a predominantly dairy farm with a very few sheep), viz: "Dairy farms" are those with a larger dairy herd (including followers) than beef. "Beef farms" are those with a larger beef herd (including followers) than dairy. "Sheep farms" are those with more sheep (including followers) than dairy cattle. 3.20 These criteria lead to cross-accounting of farms as might be expected for beef & sheep enterprises (n = 8 in Girvan and 29 in Irvine), but also for dairy and sheep (n = 4 in Girvan and 4 in Irvine).
Contained farmyard manure (FYM) and slurry system inputs 3.21 An estimate of total input to the contained waste system in operation on each farm was calculated in order to estimate the storage capacity (expressed in number of months it would take to fill the storage available) for each farm. Information regarding the calculation of storage available is given in the next section. Total input to the storage system is taken as the accumulation of: waste wash water silage effluent silo rainfall component animal waste production contained runoff from surfaces waste litter contained midden rainfall component lagoons etc- rainfall component imported wastes 3.22 Waste wash water is based on the volume of "hosing" and "other" reported by the farmer, but does not use the volume of "dairy" washings reported. Instead, this component is calculated on the assumption that each dairy cow will require 0.018 m3 water per day. This is taken as a more reliable estimate than that reported by farmers in light of the fact that some dairy farmers reported
10
no dairy washings. All waste wash water is assumed to be contained within the waste system for the purposes of this calculation. 3.23 Silage effluent volume is based on the assumption that 15% of the silage volume is expressed as effluent, and that the farm silos are eventually filled to capacity. This component is included only where farmers reported that the silo drained to the slurry system. 3.24 Silo rainfall component is calculated from the silo surface area multiplied by monthly rainfall (from Met Office data) and is included only where the silo drains to the slurry system. 3.25 Animal waste production for each animal is calculated by means of reference to look-up tables given in PEPFAA and the MAFF Water Code. Values from calculation of daily waste production (m3/animal) are assigned to production system (FYM or Slurry) according to the record of system in use, i.e. the "Muck System" field in the "Production of FYM, slurry & contaminated water" tables. Data from these tables are not inputted to contained FYM or slurry production system calculations unless the stock is recorded as "Housed", except in the case of "grazing dairy cows", in which case an occupancy factor is assumed in order to accommodate waste collected during milking times and 15% of the daily production is assumed to be contained. In addition to the codes shown on the questionnaire i.e. 1 = FYM and 2 = slurry, a code 0 was employed for occasional instances where a dual collection system was in use. In this case, the waste produced is ascribed to FYM and to slurry system on a 50/50 basis. 3.26 Contained run-off from surfaces is calculated from surface area multiplied by rainfall (from Met Office data) and includes yard/apron/close, roadways, roofs and any others reported to drain to the slurry system. 3.27 Waste litter is based on the assumption that any litter brought onto the farm ends up in either the FYM (e.g. straw) or the slurry system (e.g. sawdust). It is assumed that on average each ton of litter will account for 1 m3 input to the waste system, after use and incorporation. 3.28 Rainfall component of storage facilities is calculated from surface area of the facility × rainfall (from Met Office data) and assumes that all facilities recorded in the "FYM, slurry and effluent storage" section of the survey (other than middens) are contained within the slurry system, and that all are open to the elements. Middens are also included where they are recorded as being contained. 3.29 Imported wastes include farm, sewage, septic tank and any other waste reported as being imported onto the farm.
Calculation of surface area 3.30 In order to accommodate instances where capacity of an individual storage facility was known and reported but dimensions were not, an error handler was written utilising lookup tables to obtain a nominal average value for different types of storage facility. Where necessary this data was used to estimate surface area from capacity, but only where the depth of a facility was unknown.
11
Calculation of exclusion zone 3.31 The length of exclusion zone from watercourses where manure was applied is reported as the distance of the manure application from one side of the watercourse.
Calculation of storage capacity 3.32 Total storage capacity on each farm is taken to be the sum of volumes of all facilities recorded in the "FYM, slurry and effluent storage" section of the survey. In order to accommodate the possibility of reporting errors, the error handler described under "calculation of surface area" was also employed to ensure that a depth value was available for storage capacity calculation from reported dimensions. Again, this handler substituted values only in the absence of data.
Stage 6. Devise a prototype graphical model which contains the key elements which contribute to faecal pollution, reporting in the processes involved and transportation of faecal organisms to bathing waters. 28 February to 30 March 2000. 3.33 The basic framework of this model consists of a GIS model of the loadings of faecal pollution to soils and the subsequent transport to river reaches. This model is based on the notion of export coefficients for particular fields (distinguished by soil type, drainage system etc.) which has traditionally been used by SAC and others to estimate the inputs of nutrients to streams. 3.34 Using this approach with data collected from the survey of farm management practices and soil types, slope, distance from the stream etc., and combining with climate data such as rainfall and river discharges, loadings into rivers can be estimated. Further, combining this with a water quantity and quality model for faecal transport within a river the daily concentrations of river faecal pollutants may also be estimated. Data collected by both SEPA and CREH were used to calibrate and validate the river model. Phase 1 of the modelling work has been the construction of the relevant GIS data sets, with a view to modelling the catchment in greater detail during Phase 2.
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CHAPTER FOUR CHARACTERISATION OF THE RIVER IRVINE AND WATER OF GIRVAN CATCHMENTS 4.1 The River Irvine catchment, which includes the catchments of the River Garnock and Lugton Water, occupies an area of 706 km² in North Ayrshire. The River Irvine system flows east to west, while the River Garnock flows from north to south, meeting a shared estuary with the River Irvine on the Ayrshire Coast. 4.2 The Water of Girvan catchment, which flows in a south-west direction reaching the sea at Girvan and occupies an area of 252 km² in South Ayrshire.
SOIL TYPE 4.3
Soil maps are given in Appendices 14 and 15.
River Irvine catchment 4.4 The major soil type is imperfectly drained brown forest soils and surface-water gleys which cover 41% of the catchment area. The main features of these soil type are their moderately permeable sandy loam and sandy clay loam topsoils overlying slowly permeable clay loam subsoils. Poorly drained gley soils cover 25% of the catchment where rainfall is higher and subsoil texture is clay. This soil type will have a slowly permeable topsoil overlying a very slowly permeable subsoil. These soils will typically have an intensive pipe-drainage system that on some farms is likely to be aged and may be inefficient. The majority of intensive drainage systems were installed during the 1970s and 1980s. 4.5 While the catchment has a high percentage of clayey soils there is minimal risk of preferential flow to field drains after applications of slurry in the bathing season due to the absence of dry, deeply cracked or fissured clay soils. The mineralogy of the clay soils in Ayrshire is not high in "cracking clays" and the relatively low potential evapotranspiration rates and soil moisture deficits will also not encourage deep clay cracking. The shallow cracking which can sometimes occur in a dry summer will more likely reduce the risk of run-off and not cause preferential flow to drains. 4.6 11% of the soils are light-textured and freely drained mainly associated with raised beach and fluvioglacial deposits. The alluvial soils covering 3% of the catchment, occur along the Irvine valley and are mainly light-textured and free-draining. The remaining soil types, peaty gleys, peaty podzols and peat cover 14% of the catchment, mostly on marginal and hill land that is highly unlikely to receive manure applications.
13
Water of Girvan catchment 4.7 A distinct difference exists between the northern and southern sections of the catchment, the northern section being intensively managed brown forest soils whilst the southern section is extensively managed gleys and peaty soils. 4.8 Imperfectly drained brown forest soils dominate the catchment (42%); these soils are derived from red sandstone deposits and are generally lighter-textured and better drained than the soils of the River Irvine catchment. 20% of the soils are poorly drained gleys. Freely drained lighttextured brown forest soils and alluvial cover 10% of the catchment. The remaining soils are very poorly drained (podzols, peaty gleys, peat and regosoils) and cover the remaining upland area (28%) and are highly unlikely to have manure applied in any significant quantity.
Summary of soil types 4.9 Both catchments have a high percentage (62-66%) of imperfectly and poorly drained soils which require a risk assessment to be carried out prior to application of manure to minimise risk 14-28% of the soils in both catchments are unsuitable for manure application.
LAND-USE AND FARMING TYPES 4.10
Land-use maps are given in Appendices 24 and 25.
4.11 Manure application is only potentially suitable on arable and improved grassland which occupies 62% of the River Irvine and 38% of the Water of Girvan catchments.
State of the agricultural industry 4.12 Farm income and business confidence within farming in the River Irvine and Water of Girvan catchment is at an all time low and capital investment on farms is at a very low ebb. A recent UK survey indicates that over the next two years, almost 30% of farmers intend making no significant capital investments and a further 44% intend making no equipment purchases. A recent review by Kelly (2000) stated that as a result of the current economic climate in farming, farms building maintenance is generally considered to be an undesirable overhead and as a result many farmers give it low priority. There is a reluctance by farmers to pay professional advisers to identify maintenance items or a strategy knowing that money may not be there to complete the task. 4.13 The current lack of finance in farming may therefore indirectly result in an increased risk of a pollution incident on some livestock farms in both catchments.
14
Catchments and agricultural parishes 4.14 Both the Water of Girvan and River Irvine catchments are naturally defined geographical areas based on the watersheds. The overview of typical farming characteristics of both catchments detailed below is derived from parish data from agricultural census data (1999) shown in Appendix 26. Parish boundaries do not follow natural geographical boundaries and, thus, differences occur between the catchment boundary and the peripheral parish boundaries. This information deals primarily with those parishes which lie predominantly within the catchment boundary. Those parishes which are at the periphery of the catchment and have little land within the catchment have been discounted. This overview is based on the parishes listed below in Table 4.1. Table 4.1
Parishes with a high proportion of land area within the catchments
Catchment Water of Girvan River Irvine
Parish Daily, Kirkmichael, Straiton Dundonald, Mauchline, Sorn, Dalry, Kilbirnie, Dunlop, Fenwick, Kilmarnock, Kilmaurs, Riccarton, Stewarton, Galston, Loudon, Ardrossan, Stevenson
River Irvine catchment 4.15 The River Irvine catchment is a predominantly rural catchment where agriculture is a key socio-economic industry. The 18 parishes summarised have a total agricultural area of approximately 62,000 ha (Table 4.2). This catchment is predominantly used to rear livestock with approximately 70% of the agricultural land being improved grassland used for the intensive and extensive grazing of dairy and beef cattle and sheep. Rough grazing makes up the second largest agricultural land area with approximately 21% being used mainly for the grazing of sheep and beef cattle. Cropping is relatively unimportant to the catchment with only 5% of the total agricultural land area, being mainly used for cereal production for livestock feed. 4.16 Set-aside, fallow, woodland and other land make up together just 4% of the agricultural land area. Pigs are unimportant in that only 242 are present in the entire area. Poultry is significant in certain areas of the catchment with Dunlop having 86% of the total numbers, most likely concentrated in a few medium scale intensive units. Mauchline, Sorn and Loudon make up the majority of the rest with 12% of the pig numbers, again, most likely concentrated in a handful of small scale units.
15
Table 4.2
Land-use of main parishes in River Irvine catchment
Total improved grassland Total crops Total rough grazing Total set aside Total fallow Total woodland Total other land Total area
Area (ha) 43,672 2,834 13,174 161 51 1,357 690 61,939
% of total area 70 5 21.2 0.3 0.1 2.2 1.2 100
Water of Girvan catchment 4.17 Total area of the Water of Girvan catchment is approximately 25,200 ha. It is a predominantly rural catchment where agriculture is a key socio-economic industry. The 3 parishes summarised have a total agricultural area of approximately 18,870 ha (Table 4.3). 4.18 This land is predominantly used to rear livestock with approximately 50% of the agricultural area being poor quality rough grazing used for extensive grazing of mainly sheep and beef cattle. Improved pasture makes up the second largest land area with approximately 44% of the agricultural land used for the intensive and extensive grazing of mainly dairy and beef cattle. Cropping land covers only approximately 4% of the catchment and is mainly used for the production of livestock feed. Set-aside, fallow land, woodland and other land make up together approximately 2% of the agricultural land area. Pig rearing is unimportant in the catchment with only 20 in total. Similarly there are only 5,600 poultry, with 99% of those in Kirkmichael. Table 4.3
Land-use of main parishes in Water of Girvan catchment
Total improved grassland Total crops Total rough grazing Total set aside Total fallow Total woodland Total other land Total area
Area (ha) 8,274 702 9,396 41 0 277 138 18,870
% of total area 43.8 4 49.7 0.2 0.0 1.5 0.8 100
STOCKING DENSITIES IN EACH CATCHMENT 4.19
Livestock densities based on parish census data are shown in Appendices 8-13.
16
River Irvine catchment 4.20 Dairy cattle enterprises are concentrated around the major centres of population, Irvine and Kilmarnock, in the centre and south of the catchment. Dairy enterprises coincide with the better drained, more productive soils of the catchment and tend therefore to be at higher concentrations nearer the coast. This is significant if there is a pollution incident with manure near the coast because of the greater survival of faecal indicator organisms. Beef cattle intensity is highest in the Beith/Kilwinning area and to the south of Galston/Newmilns/Darvel. These areas coincide respectively with the poorer drained soils around Beith/Kilwinning and the higher hill ground south of Galston/Newmilns/Darvel. 4.21 Sheep enterprises are relatively unimportant in this catchment compared to dairy and beef, with only two parishes having a high intensity of sheep. The majority of the catchment has a low intensity of sheep.
Water of Girvan catchment 4.22 The highest density of dairy cattle is found on the lower lying undulating land around and to the east of Maybole, with a lower intensity towards Girvan in the west of the catchment. Beef cattle are also concentrated in the west and north of the catchment, between Maybole and Kirkmichael and Maybole and Girvan. Both dairy and beef enterprises coincide with the better drained, more productive soils of the catchment. 4.23 Dairy and beef enterprises are secondary in the east of the catchment in the hills around Straiton where sheep are the main livestock enterprise. Appendix 13 does show highest sheep intensity in the north and west of the catchment mirroring dairy and beef. However, this obscures the fact that approximately 45% of the ewe flock and 42% of the total sheep flock of the catchment are in Straiton, in the east of the catchment where hill farms predominate on poor quality rough grazing.
Catchment stocking density 4.24 Table 4.4 below shows the total numbers of each main livestock type in each catchment based on the parishes listed in Table 4.1. 4.25 The River Irvine catchment consists of approximately 1.5% of the total agricultural land area of Scotland and yet has 15% of the total number of dairy cows in Scotland demonstrating the importance of this area to Scotland’s dairy industry. Beef and sheep numbers are in the River Irvine catchment are both approximately 3% of the Scottish total for both stock. The Water of Girvan catchment has 1% of the beef cattle and 2% of the dairy and sheep in Scotland and occupies approximately 0.5% of Scotland's total agricultural area.
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Table 4.4
Total numbers of each livestock in the main parishes of each catchment parishes
Catchment River Irvine Water of Girvan
Dairy cattle 32,279 (15%) 4,061 (2%)
Total Livestock Numbers Beef cattle 13,266 (3%) 4,855 (1%)
Sheep 124,059 (3%) 86,673 (2%)
Note: The number in each catchment is given as a percentage of the total livestock numbers in Scotland
4.26 Table 4.5 indicates the average stocking density of each catchment if all livestock were grazed on improved pasture only. The average stocking density of beef meaned across each whole catchment is similar to the average beef stocking density across all the total improved grassland area of Scotland. The Water of Girvan and particularly the River of Irvine catchments contain a higher dairy stocking density when compared to the national figure. The Water of Girvan catchment is higher than Scotland is for sheep stocking densities while the River Irvine catchment is similar. Stocking densities will vary considerably from the average on a farm, field and time of year basis. Stocking density could influence run-off although averaged across each catchment, stocking densities are not high compared to other intensively farmed areas in the EU. Stocking density on a farm basis is given in Chapter 5. Table 4.5
Stocking density (number per ha) of the main parishes in each catchment
Catchment River Irvine Water of Girvan Scotland
Stocking Density (Numbers per ha) Total Livestock Numbers : Total Improved Grassland Area Dairy cattle Beef cattle Sheep 0.75 0.30 2.80 0.50 0.60 10.50 0.19 0.46 3.31
4.27 Table 4.6 shows the stocking density of each catchment if all livestock were grazed on improved pasture and rough grazing together. Dairy cattle are omitted as such enterprises are only found on improved pastures with better quality soils. Table 4.6
Stocking density (number per ha) adjusted for grazing area
Catchment River Irvine Water of Girvan Scotland
Stocking Density (Numbers per ha) Total Livestock Numbers : Total Improved Grassland Area + Total Rough Grazing Area Beef cattle Sheep 0.25 2.20 0.27 4.90 0.12 0.86
4.28 Thus, sheep enterprises are the most important stock in the Water of Girvan catchment and dairying is the significant livestock enterprise in the River Irvine catchment.
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FARM WASTE PRODUCTION DURING HOUSING AND GRAZING 4.29 An assessment of the amount of farm waste produced during both housing and grazing was assessed for each parish in both the River Irvine and Water of Girvan catchments. 4.30 SERAD parish census data on the numbers of livestock and agricultural land areas were utilised along with PEPFAA figures on waste production for different livestock. This parish information did not allow an assessment to be carried out on dilution due to rain and washing water etc. For some farms, this may dilute and consequently increase the quantity of farm waste produced during housing and also in the summer. However an assessment of this was carried out during the Farm Survey (see Chapter 5) and these results have been utilised to determine likely volumes.
Waste collected during animal housing 4.31 The amount of dairy and beef faecal waste collected during housing (assuming no dilution) was expressed as a function of the area of arable and grassland. This is calculated by the total amount of waste produced during storage divided by the total area of arable and grassland for each parish (not including rough grazing and hill land etc.). 4.32 The impact of using a 10 m exclusion zone in the catchment was calculated to be minimal using the following average figures obtained from the farmers survey (see Chapter 5). The average length of watercourse running through a farm is 1.2 km and the average farm size is 97 ha. Therefore a 10 m exclusion zone will result in only 1.2% of agricultural land being excluded. 4.33 The 38 parishes ranged in intensity of stored manure production from 3.2 to 16.9 t/ha undiluted farm waste. The parishes with the highest intensity of farm waste storage production were Symington (16.9 t/ha), Dreghorn (13.9 t/ha), Kilmaurs (13.3 t/ha), Riccarton (13.3 t/ha), Mauchline (12.6 t/ha), Craigie (11.7 t/ha), Beith (11.0 t/ha) and Tarbolton (11.0 t/ha). Full results are given in Table 4.8. Assuming an average increase of 44% as a result of water dilution the highest quantity will increase to 24 t/ha (Symington) and 20 t/ha for Dreghorn.
Farm waste production during summer grazing 4.34 The quantities of manure excreted during the spring and summer grazing period is crucial because this period corresponds to the Bathing Water season. An assessment of total dairy, beef and sheep faecal waste produced during a six month grazing period of mid April to mid October was assessed using the same criteria as described for waste collected. This includes all the manure produced during this six month period and does not include dilution or manure produced outside this period. 4.35 The 38 parishes range in intensity of faecal waste produced during grazing from 5.4 to 17.8 t/ha. The parishes with the highest amount of waste produced per ha were Symington (17.8 t/ha), Dreghorn (13.8 t/ha), Straiton (13.8 t/ha), Kilmaurs and Riccarton (both 13.4 t/ha) and Mauchline (13.1 t/ha) and Eaglesham (13.0 t/ha). Results for all 38 parishes are given in Table 4.9. The location of the parishes is very important with regard to the survival of FIO in the event of a water pollution incident. Maps showing location are given in Appendices 6 and 7.
19
4.36 During a five month bathing season (May to September, inclusive) the quantity of diluted manure applied by both grazing and slurry application in the three most intensive parishes is estimated to be 25 t/ha (Symington) 21 t/ha (Dreghorn) and 20 t/ha (Kilmaurs).
Total farm waste collected and produced by 6 months grazing and 6 months storage in each catchment 4.37 There is great variability in how much of each parish area is located in each catchment. In the case of 8 parishes (West Kilbride, Largs, Barr, Lochwinnoch, Paisley, Avondale, East Kilbride, Tarbolton) less than 10% of the parish area was located in the catchment. It was therefore assumed that livestock was evenly located throughout the parish. An estimate of livestock numbers in the part of each parish within the catchment was therefore calculated as a direct proportion of the percentage of each parish within the catchment. Summer grazing was based on a 6 month grazing period (April to September). The total amount of stored waste and waste produced for each parish within the catchment is given in Table 4.10. Table 4.7
The total amount of farm waste produced during the housing and grazing period for each catchment
Winter housing: of collected, stored and spread waste (m³) Waste produced during an April-September grazing period (m³) Totals (m³)
Catchment Irvine Girvan 562,500 87,600 436,858 90,492 999,358 178,092
4.38 These totals include an estimate of 44% dilution by water and bedding which will increase the total for the collected and spread waste by 44%.
20
Table 4.8
Production of wastes during animal storage for each parish (6 months)
Parish
Dairy Intensity Beef Waste Intensity Total amount of Intensity Percentage of Waste (t/ha) Storage (t) (t/ha) Stored Waste (t) (t/ha) parish within Storage (t) catchment W Kilbride 1,803 1.0 3,758 2.2 5,561 3.2 9 Largs 1,393 1.2 3,326 2.7 4,719 3.9 9 Barr 29 0.0 5,891 3.9 5,920 3.9 2 Neilston 5,409 1.7 7,468 2.3 12,877 4.0 22 Kirkoswald 9,473 2.7 6,167 1.8 15,640 4.5 18 Irvine 916 3.5 275 1.1 1,191 4.6 98 Stevenston 2,080 3.6 643 1.1 2,722 4.8 95 Girvan 4,102 1.4 11,038 3.8 15,140 5.2 16 Straiton 2,147 1.2 7,090 4.1 9,237 5.3 46 Dailly 8,977 3.3 7,652 2.8 16,629 6.1 92 Dundonald 10,589 5.0 2,776 1.3 13,365 6.4 43 Kilwinning 14,424 4.7 5,335 1.7 19,760 6.4 100 Maybole 30,995 5.4 9,531 1.7 40,526 7.0 19 Loudon 15,760 5.0 7,042 2.2 22,802 7.2 90 Mearns 8,185 4.2 5,881 3.1 14,066 7.3 7 Dalry 23,583 5.5 8,316 1.9 31,899 7.5 95 Kilbirnie 9,120 5.9 2,873 1.9 11,993 7.8 85 Sorn 21,675 6.6 4,552 1.4 26,227 8.0 22 Fenwick 21,026 6.4 5,281 1.6 26,307 8.0 98 Lochwinnoch 15,522 5.7 6,512 2.4 22,034 8.1 3 Paisley 5,257 5.2 3,024 3.0 8,281 8.2 1 Avondale 43,340 6.4 13,748 2.0 57,089 8.5 2 Kirkmichael 27,618 6.1 11,475 2.5 39,093 8.7 72 Dunlop 20,549 7.7 3,764 1.4 24,313 9.2 100 Galston 27,494 7.5 6,080 1.7 33,575 9.2 95 Eaglesham 14,100 7.4 3,942 2.1 18,042 9.5 19 Ardrossan 12,765 8.0 2,673 1.7 15,438 9.7 94 Stewarton 33,276 8.4 5,816 1.5 39,091 9.9 100 Kilmarnock 16,981 9.1 1,431 0.8 18,412 9.9 100 E Kilbride 25,062 7.5 8,084 2.4 33,145 9.9 1 Beith 25,214 8.4 7,603 2.5 32,817 11.0 79 Tarbolton 40,049 10.5 1,874 0.5 41,923 11.0 3 Craigie 23,907 11.3 713 0.3 24,620 11.7 28 Mauchline 34,058 11.3 3,980 1.3 38,038 12.6 52 Riccarton 19,557 11.9 1,793 1.1 21,350 12.9 100 Kilmaurs 28,849 12.9 1,058 0.5 29,907 13.3 100 Dreghorn 17,744 13.6 346 0.3 18,090 13.9 100 Symington 19,271 16.6 329 0.3 19,600 16.9 36
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Table 4.9 Parish Stevenston Neilston Kirkoswald Irvine Kilwinning Dundonald W Kilbride Loudon Paisley Fenwick Maybole Mearns Dailly Dalry Dunlop Avondale Ardrossan Girvan Stewarton Kilbirnie Sorn Lochwinnoch Kilmarnock Largs Kirkmichael Galston Tarbolton E Kilbride Beith Craigie Barr Eaglesham Mauchline Riccarton Kilmaurs Straiton Dreghorn Symington
Wastes produced during grazing (6 months) for each parish Dairy Grazing Waste (t) 2,080 5,409 9,473 916 14,424 10,589 1,803 15,760 5,257 21,026 30,995 8,185 8,977 23,583 20,549 43,340 12,765 4,102 33,276 9,120 21,675 15,522 16,981 1,393 27,618 27,494 40,049 25,062 25,214 23,907 29 14,100 34,058 19,557 28,849 2,147 17,744 19,271
Intensity (t/ha) 3.6 1.7 2.7 3.5 4.7 5.0 1.0 5.0 5.2 6.4 5.4 4.2 3.3 5.5 7.7 6.4 8.0 1.4 8.4 5.9 6.6 5.7 9.1 1.2 6.1 7.5 10.5 7.5 8.4 11.3 0.0 7.4 11.3 11.9 12.9 1.2 13.6 16.6
Beef Grazing Waste (t) 643 7,468 6,167 275 5,335 2,776 3,758 7,042 3,024 5,281 9,531 5,881 7,652 8,316 3,764 13,748 2,673 11,038 5,816 2,873 4,552 6,512 1,431 3,326 11,475 6,080 1,874 8,084 7,603 713 5,891 3,942 3,980 1,793 1,058 7,090 346 329
Intensity (t/ha) 1.12 2.31 1.78 1.06 1.73 1.32 2.17 2.22 3.01 1.60 1.65 3.05 2.81 1.95 1.42 2.04 1.68 3.80 1.47 1.87 1.38 2.39 0.77 2.75 2.54 1.66 0.49 2.43 2.54 0.34 3.88 2.07 1.32 1.09 0.47 4.08 0.27 0.28
Sheep Grazing Waste (t) 423 6,704 7,281 738 2,907 2,951 11,379 6,290 687 6,146 18,930 5,990 13,518 13,755 2,066 14,648 891 19,809 2,049 5,546 11,009 9,177 1,497 11,424 14,877 10,698 987 6,290 3,062 650 17,745 9,737 2,114 1,011 210 20,735 60 1,520
Intensity (t/ha) 0.74 2.08 2.11 2.83 0.94 1.40 6.56 1.99 0.68 1.86 3.28 3.11 4.97 3.22 0.78 2.17 0.56 6.82 0.52 3.61 3.35 3.37 0.80 9.43 3.29 2.93 0.26 1.89 1.02 0.31 11.69 5.12 0.70 0.61 0.09 11.94 0.05 1.31
Lambs Grazing Waste (t) 236 2,706 3,375 400 1,378 1,231 4,444 2,655 257 2,463 8,170 2,506 6,094 5,528 914 6,248 348 8,856 709 2,078 4,688 3,452 621 4,553 6,705 4,115 465 2,647 1,348 386 7,437 3,557 873 371 77 8,770 15 483
22
Intensity (t/ha) 0.41 0.84 0.98 1.53 0.45 0.59 2.56 0.84 0.26 0.75 1.42 1.30 2.24 1.29 0.34 0.93 0.22 3.05 0.18 1.35 1.43 1.27 0.33 3.76 1.48 1.13 0.12 0.79 0.45 0.18 4.90 1.87 0.29 0.22 0.03 5.05 0.01 0.42
Sheep & Lambs Summer Grazing Waste (t) 329 4,705 5,328 569 2,143 2,091 7,912 4,472 472 4,304 13,550 4,248 9,806 9,642 1,490 10,448 619 14,333 1,379 3,812 7,848 6,315 1,059 7,988 10,791 7,406 726 4,468 2,205 518 12,591 6,647 1,493 691 143 14,752 38 1,001
Intensity (t/ha) 0.58 1.46 1.54 2.18 0.70 0.99 4.56 1.41 0.47 1.31 2.35 2.20 3.60 2.26 0.56 1.55 0.39 4.93 0.35 2.48 2.39 2.32 0.57 6.60 2.39 2.03 0.19 1.34 0.74 0.25 8.29 3.50 0.49 0.42 0.06 8.49 0.03 0.86
Total Waste produced by Summer Grazing (t) 3,052 17,582 20,968 1,760 21,902 15,456 13,473 27,274 8,752 30,612 54,077 18,314 26,435 41,540 25,803 67,537 16,057 29,473 40,470 15,805 34,075 28,349 19,471 12,708 49,884 40,981 42,649 37,614 35,022 25,138 18,511 24,689 39,531 22,041 30,051 23,989 18,128 20,601
Intensity (t/ha) 5.3 5.4 6.1 6.7 7.1 7.3 7.8 8.6 8.7 9.3 9.4 9.5 9.7 9.7 9.7 10.0 10.1 10.1 10.2 10.3 10.4 10.4 10.4 10.5 11.0 11.2 11.2 11.3 11.7 11.9 12.2 13.0 13.1 13.4 13.4 13.8 13.9 17.8
Table 4.10 Amount of waste produced by storage and grazing in each part of parish within the catchment Water of Girvan catchment Parish Barr Girvan Kirkoswald Straiton Maybole Dailly Kirkmichael Total
Amount of stored waste in catchment (t) 97 2,356 2,816 4,284 7,892 15,334 28,051 60,830
Waste produced in parish during 6 months grazing (t) 304 3,776 4,587 10,531 11,125 24,376 35,794 90,492
River Irvine catchment Parish Paisley E Kilbride Largs W Kilbride Lochwinnoch Avondale Mearns Irvine Tarbolton Stevenston Neilston Eaglesham Sorn Dundonald Craigie Symington Kilbirnie Ardrossan Dreghorn Kilmarnock Kilwinning Mauchline Loudon Riccarton Dunlop
Amount of stored waste in catchment (t) 42 340 436 511 581 933 946 1,173 1,318 2,593 2,841 3,353 5,653 5,687 6,929 7,101 10,232 14,537 18,093 18,413 19,758 19,905 20,610 21,351 24,203
Waste produced in parish during 6 months grazing (t) 45 386 748 1,104 1,175 1,232 1,239 1,341 1,733 2,906 3,880 4,589 6,577 7,074 7,345 7,464 13,483 15,120 18,131 19,472 20,687 21,901 22,042 24,652 25,685
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River Irvine catchment (continued) Parish Fenwick Beith Kilmaurs Dalry Galston Stewarton Total
Amount of stored waste in catchment (t) 25,894 26,003 29,902 30,404 31,965 38,939 390,648
Waste produced in parish during 6 months grazing (t) 27,750 30,046 30,131 39,017 39,594 40,313 436,858
CLIMATIC DATA 4.39 The agro-climatic data for lowland Ayrshire is given in Table 4.11 and 4.12 together with rainfall data for each catchment in Appendices 16 and 17. 4.40 Both catchments have a predominantly mild windy oceanic climate with a predominance (60%) of westerly winds, the main agricultural areas being classified as warm moist lowland and warm rather wet lowland. Average annual precipitation for the lowland catchments is 1,000 and 1,200 mm rising to 1,500 mm and greater in the upper areas of the catchments (Appendices 16 and 17: Rainfall Maps). Autumn and early winter are the wettest seasons of the year with about 50% of annual rainfall falling between August and December. February usually initiates a reduction in monthly rainfall with the increased frequency of easterly winds. Thunderstorms on high ground and regular low pressure systems maintain a monthly rainfall of approximately 65-70 mm through the spring and summer months. 4.41 Temperature is closely related to altitude with a mean temperature in the main agricultural areas of about 9°C (range 3-14°C) resulting in a long growing season (end March-early December) of about 255 days. This, however, is mitigated by a period of restricted access to land due to surface wetness problems and soil field capacity. 4.42 Land access, particularly on heavier land, is limited to 175 days between early March and early October. Land application of wastes outwith this period, when the soils are at field capacity, will be restricted by the potential risk of pollution from waste run-off. The timing and quantity of manure application should also take into account crop requirements and nutrient up take. The average growing season of lowland Ayrshire is 31 March to 10 December. Periods of soil moisture deficits are limited to late June, July and August with the average maximum soil moisture deficit being 70 mm. 4.43 Mild winters result in a low incidence of frost. Severity of frosts increases away from the coast and with rising altitude. Prolonged mild rather than frosty weather results in soft, wet ground conditions restricting access to land for waste application. 4.44 Storm or very high rainfall events will be the main drivers for run-off and the frequency of these events during the bathing season (May to September) will greatly influence the risk of water pollution. Farmers should therefore be encouraged to make full
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use of the Met Office weather forecasting service to ensure that manure is not applied within two days of a storm or very high rainfall forecast. Table 4.11 Long term average climate in the main agricultural areas of Ayrshire bounded by the sea Month
January February March April May June July August September October November December Total Mean
Air temp (°C)
Rainfall (mm)
3.3 3.5 5.5 7.7 10.5 13.3 14.4 14.3 12.7 9.9 6.0 4.4
95 70 65 65 65 70 95 105 120 120 110 115 1,095
Potential Evapotranspiration (mm) 5 10 30 50 75 90 80 65 35 20 10 5 475
Sunshine (hours) 50 75 105 155 195 185 155 150 110 80 50 35 1,345
8.8
Table 4.12 Agro-climatic data for lowland Ayrshire Characteristic Access period (days) Ending field capacity Return to field capacity Maximum summer SMD (mm) Excess winter rainfall (mm) Degree - days above 0°C January - June Date of last spring air frost
Mean 175 Early March Early October 70 540 1,360 Mid April
Inter-Quartile Range 150-195 Early March – Late March Mid September - Mid October 55-90 460-625 1,280-1,450 Early April - Late April
TOPOGRAPHY AND LANDFORM 4.45 Elevation data is given in Appendices 20 and 21 and slope data for each catchment is given in the Appendices 22 and 23. A summary of the percentage area of each slope class is as follows (Table 4.13).
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Table 4.13 Percentage of land area in each slope class Slope
Run-off risk
0-3° 3-7° 7-10° 10-15° >15°
Very low Low to moderate High Very high Unacceptable
River Irvine catchment 70.9 24.4 3.4 1.1 0.2
Water of Girvan catchment 36.0 43.6 13.4 5.8 1.2
4.46 Slopes greater than 15° are deemed unsuitable for waste application because of run-off risks and tractor and tank stability/safety. Slopes of 7-15°have a significant run-off pollution risk depending on other factors. The run-off risk is usually lower with a 3-7°slope and fields with a slope of 0-3°have a very low risk of run-off in most circumstances. The River Irvine catchment contains the highest proportion of its total land area with level or slightly sloping ground (0-3°), while the Water of Girvan catchment has the highest percentage of moderate to steeply sloping ground. 4.47 The slurry run-off risk is high to unacceptable on 5-20% of the River Irvine and Water of Girvan catchments.
HYDROLOGY - THE HOST CLASSIFICATION SYSTEM 4.48 Hydrology data for each catchment, based on the Institute of Hydrology (IoH) Hydrology of Soil Types (HOST) system is given in Appendices 18 and 19.
The basis of the HOST classification system 4.49 The HOST classification is based on a number of conceptual models that describe dominant pathways of water movement through the soil and, where appropriate, substrate. Rain falling on the surface of some soils can drain freely, under the influence of gravity, so that the dominant flow pathway is a vertical one. If the underlying substrate is also permeable this vertical pathway extends into the substrate, down to the water table. At the water table, vertical movement will stop. Variations in the level of the water table will cause lateral movement of the water perhaps towards valleys and springs, and in time the water may emerge to augment streamflow. The time elapsing between rain falling and flow leaving a catchment may be long, and in such a situation the rain would be expected to have little or no influence on the short term response of the catchment but low flows will be maintained by the slow passage of water through the ground. 4.50 The characteristics of other soils restrict the vertical drainage, so that the dominant pathway for rain falling at their surface is lateral, as surface, or sub-surface runoff. In such situations the response to rainfall at a catchment outlet will be rapid and little water will be retained within the catchment to maintain the flow between rainfall events. 4.51 These are the two extreme response models within the HOST classification. The first in which water movement in the soil is mainly vertical, and the second where the dominant pathway is
26
lateral and at, or very close to the land surface. In the majority of soils the situation is, of course more complex, and a number of other response models may be suitable. 4.52 In the majority of soils in both the River Irvine and Water of Girvan catchments the dominant pathway for water movement is lateral and hence the risk of run-off from farmland of farm manures is greater.
LAND SUITABILITY OF CATCHMENT FOR MANURE APPLICATION BASED ON A RISK ASSESSMENT AND GIS 4.53 The GIS datasets were used to carry out a risk assessment based on elevation, slope angle, soil type, and land-use. Four categories were mapped for each catchment viz. unsuitable for manure application, low risk of pollution, moderate and high risk of pollution. Unsuitable land was defined as any area with a gradient greater than 15°and/or peaty soil and/or land use other than grass and arable land. The potentially suitable land remaining was divided into the following three categories based on a run-off risk low risk (slope 0-3°), moderate risk (slope 3-7°), and high risk (slope 715°). Maps of this classification for both catchments are given in Appendices 29 and 30. 4.54 This data demonstrates that 38% of the total land area in the River Irvine Catchment is unsuitable for manure application while 2% of the total area is a high risk, 19% a medium risk and the remainder (41%) is a low risk. The corresponding figures for the Water of Girvan Catchment are 58% (unsuitable), 6% (high risk), 19% (medium risk) and 17% (low risk).
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CHAPTER FIVE RESULTS OF THE FARMER SURVEY RIVER IRVINE CATCHMENT Farmer sample 5.1 There are approximately 530 farmers in the River Irvine catchment and an introductory letter was sent out to all of these farmers during the period 3-6 March 2000. SAC randomly selected a representative target sample of 200 farmers across the catchment and these farmers were telephoned and invited to participate further in the project. A total of 101 farmers in the River Irvine catchment agreed to SAC carrying out a farm visit and appraisal of farming practices. This is equivalent to approximately 50% of the farmers who were invited to participate further and 19% of the total number of registered farmers in the River Irvine catchment.
Farming types 5.2 The total area of farmland occupied by the 101 surveyed farms was 8,988 ha, which is equivalent to 12.7% of the River Irvine catchment total area. The average farm size was 97 ha (range 8 ha to 928 ha). All farms were selected on a random basis to ensure a representative sample was achieved. As would be expected with this sampling strategy a wide range in farms were surveyed including one very small one (8 ha). The number of farms with a dairy enterprise surveyed was 53 while the number of beef enterprises was 78 and sheep 52. Several farms had two or three livestock enterprises. The farms were predominantly grassland, 43 farms having some hill land or rough grazing, 81 farms with permanent pasture and 35 farms with temporary pasture. The average total number of dairy livestock (dairy cows, dry cows, dairy young stock and dairy calves) on these dairy farms was 185. While the average number of beef cattle (sucklers, finishing cattle, store cattle, bulled, bulling heifers and young stock) was 108. The average number of sheep was 298. A significant proportion of farms grow other crops (maize, 2%; winter cereals, 12%; spring cereals, 23%; rape, 3%; roots, 3%; potatoes, 1%; and others, 5.4%). 5.3 The percentage of interviewed farmers who took a first cut of silage was 90% and the average area cut was 31 ha per farm. The equivalent figures for second cut were 73% and 25 ha. Only a small proportion took a third cut (2% and 9 ha). The number of farmers who cut grass for hay was moderate (43%) and the average amount of land cut for hay was 6 ha. 5.4 During the bathing season (May to September) the median grazing intensities in the River Irvine catchment were as follows: • Dairy cows and dry cows on permanent and temporary pasture: 1.25 per ha. • Beef sucklers, finishing and store cattle on permanent and temporary pasture and rough grazing: 0.8 per ha. • Ewes on permanent pasture, temporary pasture and rough grazing: 1.96 per ha.
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5.5 These grazing intensities are relatively low compared to other areas of the UK and Europe and similar to intensities found in the Water of Girvan catchment. However grazing intensities will vary on a farm, field and time basis. The highest July grazing intensity was 5 per ha (dairy farm), 10 per ha (beef farm) and 12 per ha (sheep farm). 5.6 Aerial diagrams, layouts, photographs and plots of typical farm steadings similar to those found in the River Irvine and Water of Girvan catchments are given in SAC (1995).
General farmer awareness of PEPFAA Code and good practices 5.7 In the River Irvine catchment, 57% of farmers were aware of the PEPFAA Code and had a copy. However, only 41% of the farmers who had the Code stated that they followed it. The most common comment made by farmers was that the Code was too lengthy to read. However, a significant number of farmers had read it and were in favour of the “Do’s and Don’ts” summary at the start of each chapter. The results show that a little over half of all farmers were aware of the PEPFAA Code and its contents. Many farmers said "we apply common sense, why do we need a code?". 5.8 12% of farms have a completed farm waste management plan (FWMP). These were carried out in order to satisfy specific SEPA requirements and mostly with regard to the installation of a new storage facility of less than 6 months storage capacity. The number of dairy farms with a FWMP was 17%, while only 5% of beef enterprises had a FWMP. Out of the farmers who had a FWMP, only 69% stated that they followed it. The number of dairy farmers stating that they followed their plan was 75%, while beef farmers following their FWMP was 50%. The farmers who had a FWMP tended to have larger numbers of livestock. The percentage of farmers who stated that they accounted for the nutrient value of farm manure was assessed on a nutrient basis. 60% of farmers accounted for the nitrogen, phosphorus and potassium nutrient value of the organic manure. However, most of those farmers when questioned further were uncertain as to the actual fertiliser value. 5.9 During the farm visits, verbal advice was provided where relevant to reduce the risk of pollution. In addition approximately 80 copies of the PEPFAA Code were given out to farmers who required a copy and relevant sections highlighted (particularly section 3). Further information on this is provided in Section 5.4.
Waste wash water usage 5.10 Using stock numbers (questionnaire) and accepted usage (PEPFAA Code) average annual wash water used per dairy farm enterprise was calculated as 538 m³. Wash water from cattle standings and collecting areas is often contaminated. Wash water represents a volume of 35% of the total volume of slurry/manure (undiluted) produced by dairy cattle. 5.11 It was common for part of the wash water volume to be discharged either directly or via a 'contaminated' water tank overflow to a drain and watercourse creating a risk of FIO contamination.
29
Domestic waste system 5.12 The majority of farms (97%) have septic tanks with an average capacity of 6 m³. Septic tanks are being mainly of the traditional brick built type. It is presumed that these tanks were designed for domestic sewage. The vast majority of septic tanks are old and design parameters would not take into the account the modern style of living including the use of washing machines, dishwashers and possibly a larger use of water for personal washing, i.e. frequent use of showers. On many dairy farms the septic tanks are used frequently as a recipient of the dairy wash water. Such a use vastly overloads the volume of storage, so that the treatment of sewage in the septic tanks is compromised. 5.13 In the River Irvine catchment, 82% of septic tanks are discharged into watercourses. This contributes to the pathogen load. It should be noted that this problem would be common to any old septic tank systems designed for a lower water use. The number of the total coliform bacteria from the septic tanks outfalls will vary between 104 and 107 per litre of effluent (Henze et al., 1997). To quantify this contribution a more detailed study of septic tanks function and septic tank effluent characteristics is required. The most common frequency of emptying septic tanks was once every 5 years or greater. 61% of farmers spread emptied their septic tank sludge onto their own farm. Septic tanks are also widely associated with non-agricultural dwellings and buildings in rural Ayrshire.
Imported wastes 5.14 A very low proportion of farmers received wastes from external sources. 2% of farms received imported farm manures, which were mainly applied in July or August. No farms received any sewage sludge, septic tank waste or other imported wastes.
Rainwater contaminated by faecal matter 5.15 Rainwater contaminated directly or indirectly by stock and slurry contributes to the total volume of farm wastes. Identified areas where rainfall became contaminated are as follows: • • • •
Yards and aprons: Silage Clamps (unroofed): Roofs: Roadways:
65% of farms with 52% of these drained to slurry system 43% of farms with 76% of these drained to slurry system 40% of farms with 71% of these drained to slurry system 23% of farms with 73% of these drained to slurry system
5.16 A significant area producing contaminated rainfall is not collected and must therefore discharge and result in a risk of FIO contamination of watercourses. 5.17 Average areas of these structures (m²) where rainfall was contaminated and annual volume of contaminated rainfall produced (m³) are as follows: • Yards and aprons: • Silage Clamps (unroofed): • Roofs:
299 m² area and 325 m³ rain 446 m² area and 556 m³ rain 2,867 m² area and 3,119 m³ rain
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• Roadways:
151 m² area and 164 m³ rain
5.18 Rainfall, which originated on roofs, was by far the largest source of contaminated rainfall. Installation, repair and maintenance of all roof water systems where rainwater becomes contaminated is required on many farms. Clean surface drainage should be diverted to an appropriate clean outfall system.
Production of FYM, slurry and contaminated water during housing 5.19 The average amount of manure produced from a housed dairy herd was 1,528 t/yr. The average amount of manure produced from housed beef cattle was 320 t/yr. The majority (78%) of dairy manure produced was in the form of slurry with the remainder as farmyard manure (FYM). In the case of beef and sheep, FYM accounted for 52% and 92% of the total manure production.
FYM, slurry and effluent storage 5.20 Livestock wastes can be solid, semi-solid or liquid. Solid waste is excluded from the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 1991, but any subsequent run-off is defined as slurry, and hence subject to the Regulations. The definition of slurry includes the following: • excreta produced by livestock in a yard or building • a mixture of bedding, feed residues, rainwater and washings, containing excreta which is of a consistency which allows it to be pumped or discharged by gravity at any stage during the handling process 5.21 It is important to note that any liquids containing livestock excreta fall within the definition of slurry for the purpose of the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations, 1991. Therefore, the design of all slurry storage and transfer systems must comply with the requirements of these Regulations. 5.22 The type and volume of farm waste storage facilities occurring across all dairy and beef farms varied enormously. Average figures for both enterprises and functionality of the storage are given in Tables 5.1 and 5.2. Significantly, the functionality and the effective storage period also varied throughout all farm types. In some cases while a storage facility was classified as 'functional' operational/management failures were resulting in significant risk to the water environment (see also Table 5.25).
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Table 5.1
The percentage of dairy farms in the River Irvine catchment with each storage system, average volume and functionality Type
% of farms
Uncontained middens Contained middens Compound Field heap Slurry reception tank Brick/block/concrete tank, above ground Brick/block/concrete tank, below ground Steel tank, above ground Steel tank, below ground Earth walled lagoon, unlined Dirty water tank Other
50 33 6 6 25 19 77 52 2 2 15 8
Table 5.2
Average volume (m³) 283 298 52 183 267 482 452 1,148 158 140 101 118
Functionality (% satisfactory) 0 88 67 60 95 92 92 94 100 0 63 80
The percentage of beef farms in the River Irvine catchment with each storage system, average volume and functionality Type
Uncontained midden Contained midden Compound Field heap Slurry reception tank Brick/block/concrete tank, above ground Brick/block/concrete tank, below ground Steel tank, above ground Steel tank, below ground Earth walled lagoon, unlined Dirty water tank Other
% of farms 56 28 5 7 21 19 37 21 9 2 7 5
Average volume (m³) 344 297 388 189 201 453 131 722 30 992 12 20
Functionality (% satisfactory) 0 93 100 67 89 90 88 90 75 100 50 33
5.23 PEPFAA requirements were used to determine whether the storage facility was functional or not if the storage system met the requirements given in PEPFAA it was considered functional. 5.24 Middens were the most common source of potential pollution. The effluent from middens was contained within the slurry system on only 59% of dairy farms and 45% of beef farms. This lack of effluent containment on about half of all farm middens represents a high FIO contamination risk. The slurry from middens needs to be collected, stored and managed. Drainage from middens located within farm steadings is by definition (under the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 1991) slurry, which must be collected prior to disposal. Therefore there is a requirement to provide storage capacity for up to the maximum quantity of slurry which is likely to be produced in any continuous 6 month period. Alternatively, this slurry could be transferred via a small tank to existing or extended slurry storage elsewhere on the farm. The Control of Pollution (Silage, Slurry and Agricultural Fuel Oil)
32
(Scotland) Regulations 1991 require that no part of the system must be sited with 10 m of a watercourse which effluent could enter if it were to escape. 5.25 It is important to note that while some types of storage facility represent a much lower total capacity they can represent a high and significant risk depending on standards of operation and management. These specifically include below ground 'dirty water tanks' found on 11% of farms. 5.26 While most high level slatted buildings had 'functional' storage below the slatted areas, the subsequent containment and handling of 'drainage and slurry' from these buildings was variable. From an random sample of 20 farms, a significant number were not being contained. A few buildings were without any tank for collection of drainage, however in all cases where drainage was directed to a separate tank (rather than slurry storage) the tank was now considered too small to prevent overflow. The effluent of high level slatted buildings was therefore not properly contained and presents a pollution risk. 5.27 While management problems were thought to predominant during winter months when rainfall on associated 'lower' aprons was greatest. It is suggested here that significant discharge effects may occur where either stocking of the building continues into the 'summer' season and/or where the contents of such buildings are not emptied before first or second cut silage is made. 5.28 Compounds and lagoons made up a small proportion of the total storage sample (7%). A small proportion of the compounds were found to represent a risk of faecal contamination of watercourses due to their condition and/or arrangement. 5.29 Most of the farms sampled stored FYM within buildings (as bedded area) and/or on designated 'midden' sites. A low number of field heaps were apparent (6% of farms), although around one third of field heaps were not satisfactory. 5.30 The available waste storage capacity is inadequate on a high proportion of farms. 21% of farms had less storage than 1 month of the farm’s waste production. The equivalent figures for 1-2 months was 18%; 2-3 months, 10%; 3-4 months, 12% and 4-5 months, 9%. 29% of farms had more than 5 months storage available, while 71% had less than 5 months storage. The provision of adequate storage capacity for 6 months’ slurry production is a requirement for new, substantially enlarged or substantially reconstructed slurry storage installations under the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil (Scotland) Regulations 1991). This would allow a farmer to delay spending slurry until spreading conditions were suitable. The acceptance of storage capacity for less than 6 months must be demonstrated by an acceptable FWMP which has been agreed with SEPA.
33
Utilisation of FYM, slurry and contaminated water Dairy farms 5.31 The percentage of dairy farms using farm staff to spread their own FYM was 85%, while 8% used a contractor and 7% used a combination of contractor and farm staff. The percentage of dairy farms using farm staff to spread their farm’s slurry was 38%, while 11% solely used a contractor and 51% used a combination of contractor and farm staff. The percentage of dairy farms using farm staff to spread their farm’s dirty water was 66%, while 17% solely used a contractor and 17% used a combination of contractor and farm staff.
Beef farms 5.32 The percentage of beef farms using farm staff to spread their own FYM was 79%, while solely 9% used a contractor and 12% used a combination of contractor and farm staff. The percentage of beef farms using farm staff to spread their farm’s slurry was 56%, while 24% solely used a contractor and 18% used a combination of contractor and farm staff. The percentage of beef farms using farm staff to spread their farm’s dirty water was 75%, while 25% used a contractor. 5.33 For both dairy and beef farms, contractors spread substantial quantities of manure, particularly slurry.
Farm waste spreader type and system 5.34 The type of waste spreading system used may determine the range of handling rates and therefore the time taken to apply a stored volume of manure, slurry and/or contaminated water. It will influence the potential to carry out spreading in suitable conditions (field and weather) using a limited amount of time available. 5.35 In some cases low ground pressure equipment intended to reduce field damage by compaction allows access to fields in wet conditions (usually unsuitable for conventional spreaders) which can be unsuitable for spreading because of a water pollution risk. 5.36 Most used equipment for land application on dairy farms was a vacuum tanker (85% ownership). A solid muck spreader was also owned but handled significantly less material (85% ownership). A lower percentage of beef farms had vacuum tankers (47% ownership), 86% having a solid muck spreader. While all farms have access to a contractors umbilical system these were used (not exclusively) by 20% of dairy farmers and 7% of beef farmers. Overall results are shown in Tables 5.3 and 5.4.
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Table 5.3
The percentage of dairy farms the River Irvine catchment which have access to different types of spreader systems
System Vacuum, open or dual tanker Solid muck spreader Multipurpose Umbilical
% dairy farmers using this equipment 85 85 2 19
% of users who have low ground pressure tyres 46 17 0 78
Most common distribution system Splash plate Rotary N/A Splash plate
Note: A high proportion of farmers had access to more than one spreader so the percentages do not total to 100%.
Table 5.4
The percentage of beef farms in the River Irvine catchment which have access to different types of spreader systems
Vacuum, open or dual tanker Solid muck spreader Multipurpose Umbilical
% beef farmers using this equipment 47 86 7 7
% of users who have low ground pressure tyres 80 30 67 100
Most common distribution system Splash plate Rotary N/A Splash plate
Note: A high proportion of farmers had access to more than one spreader so the percentages do not total to 100%.
Application of farm waste Dairy farms 5.37 Target waste application rates were set on 65% of dairy farms and followed on 97% of these farms. Farmers were asked to record both their minimum and maximum application rate of manure. The average minimum application rate was 19 m³/ha, while the average maximum was 28 m³/ha. The actual maximum stated application rate out of all the dairy farms was 50 m³/ha. 19% of farmers kept written records of the application rates and 86% used an exclusion zone to protect watercourses. The width of exclusion zone was not determined for all farms although in practically all cases it was usually less than 10 m, but greater than 3 m.
Beef farms 5.38 Target application rates were set on 37% of beef farms and followed on 100% these farms. The average minimum application rate was 19 m³/ha, while the average maximum was 28 m³/ha. The actual maximum stated application rate out of all the beef farms was 40 m³/ha. 7% of farmers kept written records of the application rates and 85% used an exclusion zone to protect watercourses. Again, the width of exclusion zone was not determined, although in many farms it was greater than 3 m and less than 10 m. 5.39 A high proportion of farmers do not formally have set waste application rates but rather "spread it at a rate that looks right". However practically all the sampled farmers do not exceed and
35
are lower than the 50 m3/ha maximum rate stated by PEPFAA. Further work is recommended to develop a graduated application rate based on soil, and, timing and weather factors. The vast majority of farmers use buffer strips to protect water but the width is usually not greater than 5 m.
Farmer appraisal of field suitability for a manure or slurry application 5.40 A high proportion (84-95%) of dairy and beef farmers took ground conditions and current weather into account to decide if a field was suitable for a manure application (Table 5.5). Clearly there is a risk of pollution on the 6-16% of livestock farms who do not claim to take current weather or ground conditions into account. More than half of all livestock farmers did not take soil type or slope into account while 37% did not account for watercourses. There is a well proven risk of pollution if manure is applied to inappropriate soil types or on steep slopes (greater than 15°) particularly if the field is next to a watercourse. However an unknown, potentially large percentage of farmers who did not say they took these factors into account may have been fully aware that their soil type, slope or proximity to watercourses was satisfactory on the fields they used for application. Some farmers may therefore have recorded that they did not take account of these variable because they did not have, for example, steeply sloping land or very heavy soils on the fields where manure was used. Table 5.5
The percentage of farmers in the River Irvine catchment who took certain factors into consideration in deciding if a field was suitable for a manure application Suitability factor
Soil type Ground conditions Slope Current weather Weather forecast Watercourses Housing Other factors
% dairy farmers 42 94 35 85 31 63 19 17
% beef farmers 49 95 42 84 37 63 14 12
5.41 Ground conditions and current weather were therefore the main factors used by farmers to determine if a field was suitable for farm waste application.
Type of land where waste was applied 5.42 The percentage of farmers who applied some or all of their farm waste to certain land classes is given in Table 5.6. A checklist guide to land suitability and pollution risk from manure application is given in Appendix 5.
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Table 5.6
Type of land receiving farm manures in the River Irvine catchment
Soil type
Surface condition at spreading
Slope
Drainage status
Field drainage (approx. % of each type)
Flood risk (approx. % of each type)
Light Medium Heavy Very heavy/peaty Well vegetated Dry Not waterlogged Frozen Not compacted or rutted 15o Free Imperfect Poor Very poor >0.6 m deep With permeable fill Surface drains Recently subsoiled Recently moled None 1 in 5 years >1 in 5 years
Dairy (%) 3 54 34 9 27 65 96 46 65 49 49 2 20 58 16 6 84 8 5 2 0 97 3 0
Beef (%) 4 37 47 11 7 95 35 51 16 48 45 7 20 38 32 9 93 4 3 0 0 98 1 1
5.43 9-11% of farmers apply some waste to a soil type with a potentially high risk of water pollution (very heavy or peaty soil). 46-51% of farmers apply some wastes on to frozen ground which also has an increased risk of water pollution following a thaw on sloping ground. There may be a lower risk on flat ground provided there are no watercourses neighbouring the field. In Ayrshire, a substantial amount of slurry is spread when the ground is frozen although this practice is not recommended in PEPFAA. If more farmers were constrained from applying slurry to frozen ground, undoubtedly more slurry would be applied close to or during the bathing season. Further advice should be given in the next revision of PEPFAA on what circumstances it would be suitable to spread on frozen ground. Parkes et al. (1997) stated that infiltration on frozen soils is dependent on the soil water content when freezing occurs. Stefens and Corenz (1993) recommend that slurry can be applied to shallowly frozen soil (15°) and 69% apply to very poorly drained land, both very high risk situations. Clearly these practices are not recommended in the PEPFAA code and are unacceptable because the likelihood of FIO contamination of any nearby watercourse. 34-47% of farmers applied manure to heavy soils, 4549% to slopes of 3-15o and 37-54% of farmers applied manures to imperfectly drained land. These conditions are moderately suitable and the risk of pollution will be dependent on specific circumstances. The PEPFAA code maximum recommendation of 50 m3/ha manure will not be appropriate for all these circumstances and a graduated scale of reduced applications
37
should be considered, based on soil conditions and slope. Many farmers who were unaware of the contents of PEPFAA code used a "common sense" approach to assessing application rate and pollution risk. Only one farmer interviewed applied wastes to land which may be regularly flooded, although this activity is likely to occur outside the bathing season. 5.45 Manure was incorporated on 13% of dairy farms and 24% of beef farms. However this was mainly a small proportion of the total farm waste production and usually only applied to grassland or arable which was to be shortly ploughed and planted.
Time of waste application 5.46 The percentage of dairy and beef farmers who apply farm waste on each of the months of the year is given in Tables 5.7 and 5.8 respectively. Table 5.7
Waste type FYM Slurry Dirty water Other
Time of application of farm waste for dairy farmers in the River Irvine catchment
Jan 3 5 4
Feb 9 10 16
Mar 29 27 5
Time of Application to Land (as %) Apr May Jun Jul Aug Sep 21 3 3 3 4 8 10 1 23 4 5 3 18 3 16 6 8 2
8
8
9
8
8
9
8
8
9
Oct 6 4 6
Nov 6 2 5
Dec 3 5 12
8
8
9
5.47 Application of manure without low ground pressure tyres when soils are at field capacity (early October to early March) may result in localised soil compaction. In severe cases, this in turn may increase the risk of slurry run-off from a later application during the May to September bathing period. Table 5.8
Waste type FYM Slurry Dirty water Other
The percentage of beef farmers in the River Irvine catchment who apply farm waste on each of the months of the year
Jan 7 4 4 0
Feb 6 5 4 0
Mar 29 26 8 0
Apr 27 24 8 0
Time of Application to Land (as %) May Jun Jul Aug Sep 4 3 4 10 3 1 12 13 2 1 8 30 8 8 8 0
0
0
0
0
Oct 3 7 8 0
Nov 1 1 4 0
Dec 4 5 4 0
5.48 During May to September, 36% of the total collected slurry from dairy cattle is applied to farmland. On beef farms (Table 5.8), 29% of the total slurry is applied during this period.
Land use category receiving waste application
38
5.49 The percentage of farms applying some or all of their farm waste to each land use category is given in Table 5.9 for dairy farms and Table 5.10 for beef farms. Table 5.9
The percentage of dairy farms in the River Irvine catchment applying some or all of their farm waste to each land use category
Land-use Grass for grazing Grass for silage/hay Arable Rough grazing Other
Proportion of waste applied to each land use category (as %) FYM Slurry Dirty water Other 24 19 34 0 44 80 64 0 31 0 2 0 0 0 0 0 0 0 0 0
Table 5.10 The percentage of beef farms in the River Irvine catchment applying some or all of their farm waste to each land use category
Land-use Grass for grazing Grass for silage/hay Arable Rough grazing Other
Proportion of waste applied to each land use category (as %) FYM Slurry Dirty water Other 23 17 40 0 63 81 60 0 14 2 0 0 0 0 0 0 0 0 0 0
5.50 Slurry was predominantly applied to silage or hay fields (80-81%) with 17-19% being applied to grazing fields. FYM was also mainly applied to silage fields (44-63%) although grazing and arable land each also received appreciable quantities (14-31%).
WATER OF GIRVAN CATCHMENT 5.51 Many of the pollution risks identified in the Water of Girvan catchment are the same as risks identified for the River Irvine catchment (section 5.1 to 5.50). Sections 5.20 to 5.30 also refer to the legislative framework for controlling farm wastes (Control of Pollution (Silage, Slurry and Agricultural Fuel Oil (Scotland) Regulations 1991), which is directly relevant to both catchments.
Farmer sample 5.52 There are approximately 89 farmers in the Water of Girvan catchment and an introductory letter was sent out to all of these farmers during the period 3-6 March 2000. SAC randomly selected a representative sample of farmers across the catchment and these farmers were telephoned and invited to participate further in the project. A total of 20 farms (16 farmers) in the Water of Girvan catchment agreed to SAC carrying out a farm visit and appraisal of farming practices. All the farmers who were invited to participate further agreed to do so, 18% of the total number of farmers in the Water of Girvan catchment were surveyed.
39
Farming types 5.53 The total area of farmland occupied by the 20 surveyed farms was 3,940 ha, which is equivalent to 15.7% of the Water of Girvan catchment total area. The average farm size was 281 ha (range 25 ha to 1,122 ha). The farms were predominantly grassland, with farms having some hill land or rough grazing, 14 farms with permanent pasture and 2 farms with temporary pasture. A significant proportion of farms grow other crops (winter cereals, 37%; spring cereals, 69%; roots, 31%; potatoes, 30%; and others, 31%. No maize or oilseed rape was grown on the sampled farms. 5.54 The percentage of farmers who made a first cut of silage was 82% and the average area cut was 35 ha per farm. The equivalent figures for second cut were 56% and 31 ha. Only a small proportion took a third cut (6% and 21 ha). The amount of farmers who cut grass for hay was moderate (31%) and the average amount of land cut was 22 ha. A total of 5 farmers had a dairy enterprise while 11 had some beef cattle and 12 had a sheep enterprise. Several farms had 2 or 3 livestock enterprises. However grazing intensities will vary on a farm, field and time basis. The highest July grazing intensities was 2 per ha (dairy farm), 3 per ha (beef farm) and 5 per ha (sheep farm).
General farmer awareness of good practices 5.55 In the Water of Girvan catchment, 88% of farmers were aware of the PEPFAA Code and had a copy. However, only 50% of the farmers who had the Code stated that they followed it. The most common comment made by farmers was that the Code was too lengthy to read. However, none of the farmers had a FWMP available. The percentage of farmers who stated that they accounted for the nutrient value of farm manure was assessed on a nutrient basis. 88% of farmers reported that they accounted for the nitrogen, phosphorus and potassium nutrient value of manure.
Waste wash water usage 5.56 Using stock numbers (questionnaire) and accepted usage (PEPFAA Code) average annual wash water used per dairy farm enterprise was calculated as 752 m³. Wash water is often contaminated from cattle standings and collecting areas. Wash water represents a volume of 30% compared to the volume of slurry/manure (undiluted) produced by dairy cattle. It was common for part of the wash volume to be discharged either directly or via a 'contaminated' water tank overflow to a drain and watercourse.
40
Domestic waste system 5.57 The majority of farms (88%) have septic tanks with an average capacity of 8 m³. Septic tanks were mainly of the traditional brick built type and 81% of the tanks discharged to a watercourse. The most common frequency of emptying was every 5 years or more and 69% of farmers spread emptied septic tank contents onto their own farm. In the catchment there will also be other septic tanks from non-agricultural dwellings and buildings.
Imported wastes 5.58 A large proportion of farmers received wastes from external sources. 38% of farms received imported farm manures which were mainly applied in July or August. No farms received any externally produced sewage sludge, septic tank waste or other imported wastes.
Rainwater contaminated by faecal matter 5.59 Rainwater contaminated directly or indirectly by stock slurry contributes to the total volume containing faecal material. Identified areas where rainfall became contaminated are as follows: • Yards and aprons: 56% • Silage Clamps (unroofed): 56% of farms with 64% of these drained to slurry system • Roofs: 100% 5.60 A significant area producing contaminated rainfall is not collected and must therefore discharge resulting in a FIO risk to watercourses. 5.61 Average areas of these structures (m²) where rainfall was contaminated and annual volume of contaminated rainfall produced (m³) are as follows: • Yards and aprons: 179 m² area and 204 m³ rain • Silage Clamps (unroofed): 540 m² area and 616 m³ rain • Roofs: 733 m² area and 837 m³ rain
Production of FYM, slurry and contaminated water during housing 5.62 The average amount of manure produced from housed dairy cows and calves was 2,670 t/yr. The average amount of manure produced from housed beef cattle was 949 t/yr on beef farms, while the equivalent figure for housed sheep was 89 t/yr (all farms). 5.63 The majority (76%) of dairy manure produced was in the form of slurry with the remainder as FYM. In the case of beef and sheep, farmyard manure accounted for 76% and 100% of the total manure production.
41
FYM, slurry and effluent storage 5.64 The type and volume of farm waste storage facilities occurring across all dairy and beef farms varied greatly. Average figures for both enterprises and functionality of storage are given in Tables 5.11 and 5.12.
Table 5.11 Storage of farm manures on dairy farms in the Water of Girvan catchment Type
% of farms
Uncontained middens Contained middens Field heap Slurry reception tank Brick/block/concrete tank, below ground Steel tank, above ground Weeping walled lagoon
0 20 20 40 40 60 20
Average volume (m³) N/A 225 400 15 1,167 1,139 1,260
Functionality (% Satisfactory) N/A 100 100 100 100 100 0
Table 5.12 Storage of farm manures on beef farms in the Water of Girvan catchment Type
% of farms
Midden – uncontained Field heap Slurry reception tank Brick/block/concrete tank, above ground Brick/block/concrete tank, below ground Steel tank, above ground Dirty water tank Slurry separator Other
20 70 6 10 50 25 10 0 0
Average volume (m³) 373 2,529 15 1,485 1,641 1,040 13 0 0
Functionality (% Satisfactory) 0 100 100 100 100 100 100 N/A N/A
5.65 PEPFAA requirements were used to determine whether the storage facility was functional or not. 8% of farms had less storage than 1 month of the farm’s waste production. The equivalent figures for 1-2 months was 8%; 2-3 months, 8%; 3-4 months, 23% and 4-5 months, 15%. 38% of farms had more than 5 months storage available. The two dairy farmers who had apparently very limited storage facilities had very low numbers of young stock or dry cows only (10-20 animals). However these farmers utilised the stock housing area for waste storage as well as field heaps. 5.66 The results from the Water of Girvan catchment must be treated with caution as this is only based on 16 farmers (20 farms).
42
Utilisation of FYM, Slurry and contaminated water Dairy farms 5.67 The percentage of dairy farms using farm staff to spread their farm’s FYM was 100%. The percentage of dairy farms using farm staff to spread their farm’s slurry was 80%, while 20% used a combination of a contractor and farm staff.
Beef farms 5.68 The percentage of beef farms using farm staff to spread their farm’s FYM was 100%. The percentage of beef farms using farm staff to spread their farm’s slurry was 83%, while 17% used a contractor.
Farm waste spreader type and system 5.69 The type of spreading equipment used by a farmer is important because this will dictate the handling rate and therefore the farmers ability to spread during a limited period of suitable conditions. The most common spreader for dairy farmers (Table 5.13) was a vacuum tanker while a solid muck spreader was the most common spreader on beef farmers (Table 5.14). 20% of dairy farmers had access to an umbilical system with low ground pressure tyres. Table 5.13 The percentage of dairy farms in the Water of Girvan catchment which have access to different types of spreader systems Spreader type Vacuum, open or dual tanker Solid muck spreader Multipurpose Umbilical
% dairy farmers using this equipment 100 40 60 20
% of users who have low ground pressure tyres 60 0 0 100
Most common distribution system Splash plate Rotary N/A Drop pipes
Note: A high proportion of farmers had access to more than one spreader so the percentages do not total to 100%.
Table 5.14 The percentage of beef farms in the Water of Girvan catchment which have access to different types of spreader systems Spreader type Vacuum, open or dual tanker Solid muck spreader Multipurpose Umbilical
% beef farmers using this equipment 40 50 50 0
% of users who have low ground pressure tyres 25 0 0 N/A
Most common distribution system Splash plate Rotary N/A N/A
Note: A high proportion of farmers had access to more than one spreader so the percentages do not total to 100%.
43
Application of farm waste 5.70 The type of waste spreading system used will determine the range of handling rates and therefore the time taken to apply a stored volume of manure, slurry and/or contaminated water. It will influence the potential to carry out spreading in suitable conditions (field and weather) using a limited amount of time available. In some cases low ground pressure equipment intended to cause reduced field damage by compaction allows access to fields in wet conditions which would be unsuitable for spreading. Most used equipment for land application on dairy farms was a vacuum tanker (100% ownership). A solid muck spreader was also owned but handled significantly less material (40% ownership). 60% of farmers had a multipurpose spreader. A lower percentage of beef farms had vacuum tankers (40% ownership), 50% having a solid muck spreader and 50% a multipurpose spreader. While all farms have access to a contractors umbilical system these were used (not exclusively) by 20% of dairy farmers and no beef farmers. Overall results are shown in Tables 5.13 and 5.14.
Farmer appraisal of field suitability for a manure application 5.71 As for the River Irvine catchment, ground conditions and current weather were the main criteria used by farmers to determine if a field was suitable for an application of farm waste (Table 5.15). Clearly there is a potential risk of pollution on the 10-30% of beef farms who do not take current weather and ground conditions into account to decide if a field is suitable for a manure application. In addition a low percentage of beef farmers (20-40%) took the weather forecast and watercourses into account. Table 5.15 The percentage of farmers in the Water of Girvan catchment who took certain factors into consideration to decide if a field was suitable for a manure application
Soil type Ground conditions Slope Current weather Weather forecast Watercourses Housing Others
% dairy farmers 80 100 40 100 80 80 0 0
% beef farmers 70 70 20 90 20 40 10 0
Type of land where waste was applied 5.72 The percentage of farmers who applied some or all of their farm waste to certain land classes is as follows in Table 5.16. Manure was not incorporated on any of the dairy or beef farms. 18% of dairy farmers apply manures to poorly drained land although no farmers applies manures to waterlogged soils. 19-25% of farmers apply manures to imperfectly drained land and 19-20% of farmers apply manures onto heavy soils while 54-59% apply onto slopes of 3-15o. These conditions may be suitable in certain circumstances but not always and the risk of pollution will
44
depend on individual conditions. 2-3% of farmers apply some manures to very heavy or peaty soils or to fields with a flood risk. These practices are risky with regard to water pollution. 5.73 16% of farmers apply some manure onto land with a slope greater than 15°which clearly represents an unacceptably high risk of run-off and pollution. Table 5.16 Type of land receiving farm wastes in the Water of Girvan catchment Soil type
Surface condition at spreading
Slope
Drainage status
Field drainage (approx. % of each type)
Flood risk (approx. % of each type)
Light Medium Heavy Very heavy/peaty Well vegetated Dry Not Waterlogged Frozen Not Compacted or rutted 15° Free Imperfect Poor Very poor >0.6 m deep With permeable fill Surface drains Recently subsoiled Recently moled None 1 in 5 years >1 in 5 years
Dairy (%) 19 60 19 2 0 100 100 0 60 25 59 16 63 19 18 0 84 8 0 0 0 97 1 2
Beef (%) 30 47 20 3 60 90 100 80 0 30 54 16 69 25 3 3 63 14 0 0 0 96 1 3
Time of waste application 5.74 The percentage of dairy and beef farmers who apply some of their waste at different times of the year is given in Table 5.17 (dairy) and Table 5.18 (beef).
45
Table 5.17 The percentage of dairy farmers in the Water of Girvan catchment who apply some or all of their farm waste on each month of the year
FYM Slurry Dirty water Others
Jan 2 4 4
Feb 0 11 16
Mar 37 23 16
0
0
0
Apr 21 25 39 0
May 0 0 0
Jun 0 15 0
Jul 11 3 0
Aug 8 2 6
Sep 14 4 8
0
0
0
0
0
Oct 0 5 4 0
Nov 8 3 4
Dec 0 3 4
0
0
Table 5.18 The percentage of beef farmers in the Water of Girvan catchment who apply some or all of their farm waste on each month of the year Time of Application to Land (as %)
FYM Slurry Dirty water Others
Jan 17 6 0
Feb 13 4 0
Mar 21 27 0
Apr 23 23 0
May 0 2 0
0
0
0
0
0
Jun 0 16 0
Jul 0 8 0
0
0
Aug 6 0 0 0
Sep 5 0 0
Oct 0 4 0
0
0
Nov 6 4 0
Dec 9 4 0
0
0
5.75 The first four months of the year, particularly March and April were the most common months for manure application. During the bathing season (May to September) slurry was commonly applied after first cut silage while FYM application occurred in August and September (and July on beef in farms but not dairy farms).
Land use category receiving waste application 5.76 On dairy farms slurry was particularly applied to silage land while FYM was mainly applied to arable crops (Table 5.19). Results were similar on beef farms (Table 5.20). Table 5.19 The percentage of dairy farms in the Water of Girvan catchment applying some or all of their farm waste to each land use category
Grass for grazing Grass for silage/hay Arable Rough grazing Other
Proportion of waste applied to each land use category (as %) FYM Slurry Dirty water Other 10 7 0 0 0 93 0 0 73 0 0 0 0 0 0 0 18 0 0 0
46
Table 5.20 The percentage of beef farms in the Water of Girvan catchment applying some or all of their farm waste to each land use category is given in the table below
Grass for grazing Grass for silage/hay Arable Rough grazing Other
Proportion of waste applied to each land use category (as %) FYM Slurry Dirty water Other 0 8 0 0 8 74 0 0 90 18 0 0 0 0 0 0 3 0 0 0
Watercourses at Risk from Waste Application and Livestock Grazing River Irvine catchment Length of watercourses potentially at risk 5.77 An estimation was made of the total length of watercourse running alongside or next to land used for manure application. As well as streams and rivers, watercourses included field ditches and culverts which were commonly running throughout the year. Where the watercourse ran between two fields used for manure, both banks were calculated. 5.78 The average total length of watercourse running alongside or next to land used for farm manure application was 1.24 km (range 0.1 km to 3.2 km) on dairy farms. For beef farms an average of 0.93 km (range 0.03 km to 3.3 km) of watercourses bounded or ran alongside land used for manure application. The percentage of farmers who reported a watercourse adjacent to some of their land used for waste application was very high (90 and 93% for dairy and beef respectively). Poorly managed manure application on these fields will therefore result in a potential pollution risk.
Farm water supply 5.79 The farm water supply was surveyed because the PEPFAA Code indicates that manure should not be applied within 50 m of a borehole. Poor manure management could also result in faecal contamination of surface, spring or borehole water and thereby potentially affect the health of humans or livestock consuming this water. Mains water was the most commonly used water source although 37% of beef farmers and 59% of sheep farmers also utilised a private source from a spring in the River Irvine catchment (Table 5.21). Results for the Water of Girvan catchment are given in Table 5.24.
47
Table 5.21 The percentage of farms in the River Irvine catchment using various sources of water, averaged across the livestock enterprises Source of water Mains Private from surface Private from spring Private from borehole
Dairy (%) 79 2 15 8
Beef (%) 67 0 37 5
Sheep (%) 59 0 59 0
Note: Several farmers utilised more than one water source and will have been counted twice, therefore resulting in totals greater than 100%.
Watering system in grazing fields 5.80 The watering system used in grazing fields was surveyed to assess the potential of FIO contamination if large amounts of stock were drinking in watercourses (Table 5.22 and 5.24). Ditches, burns and rivers were utilised for watering in 25-44% of the farms in the River Irvine catchment (Table 5.22) and 24-29% (Table 5.24) of the Water of Girvan catchment farmers. Table 5.22 The percentage of farmers in the River Irvine catchment using various watering systems in their grazing fields, averaged across the livestock enterprises Watering system in grazing field Mains trough Spring, well, borehole, trough Ditch, burn or river Pond or loch Bowser None
Dairy (%) 60 15 25 0 0 0
Beef (%) 48 11 40 0 1 0
Sheep (%) 45 10 44 0 1 0
5.81 There was no direct evidence that livestock were excreting directly into water although it is likely that faecal matter excreted on the banks of a ditch or stream may enter the watercourse through soil erosion as a consequence of animal movement or run-off during periods of high rainfall. 5.82 The percentage of farmers who used a ditch, burn, river, pond or loch as a watering system in 50% or more of their grazing fields was 19% (dairy), 28% (beef) and 41% (sheep). Out of the farms which used ditches, burns and rivers, the total average length of watercourse used for watering stock was 1.4 km (dairy), 2.4 km (beef) and 3.2 km (sheep). Heavy reliance on ditches and burns for livestock drinking may result in an increased risk of faecal contamination in these watercourses.
Field access through watercourses 5.83 The percentage of farms with regular stock movement through watercourses was 13% (dairy), 19% (beef) and 24% (sheep). The average number of crossings made daily were 1.7 (dairy), 1.5 (beef) and 1.5 (sheep). Depending on circumstances and scale, this may contribute to an increased risk of faecal contaminated watercourses at the farm.
48
Water of Girvan catchment 5.84 The average total length of watercourse on land used for farm waste application was 0.93 km (range 0.50 km to 2.0 km) on dairy farms. For beef farms an average of 1.54 km (range 0.5 km to 2.5 km) of watercourses bounded land used for waste application. The percentage of farmers who reported a length of watercourses next to some of their land used for waste application was 80%. Farm water supply Table 5.23 The percentage of farms in the Water of Girvan catchment using various sources of water, averaged across the livestock enterprises Source of water Mains Private from surface Private from spring Private from borehole
Dairy (%) 100 0 0 0
Beef (%) 100 0 30 0
Sheep (%) 92 0 25 0
5.85 Several farmers utilised more than one water source and will have been counted twice, therefore resulting in totals greater than 100%. Watering system in grazing fields Table 5.24 The percentage of farmers in the Water of Girvan catchment using various watering systems in their grazing fields, averaged across the livestock enterprises Watering system in grazing field Mains trough Spring, well, borehole, trough Ditch, burn or river Pond or loch Bowser None
Dairy (%) 71 0 29 0 0 0
Beef (%) 69 7 24 1 0 0
Sheep (%) 65 6 28 1 0 0
5.86 The percentage of farmers who used a ditch, burn, river, pond or loch as a watering system in 50% or more of their grazing fields was 0% (dairy), 10% (beef) and 13% (sheep). Out of the farms which used ditches, burns and rivers, the total average length of watercourse used for watering stock was 1.4 km (dairy), 2.4 km (beef) and 2.7 km (sheep).
Field access through watercourses 5.87 The percentage of farms with regular stock movement through watercourses was 60% (dairy), 10% (beef) and 13% (sheep). The average number of crossings made daily were 1.33 (dairy), beef and sheep numbers were not determined.
49
RISKS OF FAECAL CONTAMINATION TO WATERCOURSES AND BATHING WATERS Potential FIO sources from farms 5.88
Faecal contamination of watercourses can be the result of: • Material transported into watercourses by non-collection, no containment or poor containment facility (leakage). • Surface run-off following poorly managed grazing or land application of manure in adverse conditions (e.g. high rainfall during and following land application).
5.89 Point discharges into watercourses can be expected from many farms. They mainly include the leakage from uncontained middens, poorly designed or mis-managed waste storage facilities, high level slatted courts and self feed silage aprons, farmyards and cow tracks. Although the seepage from middens with stored and composted FYM can be relatively low in FIO, the fresh manure and other sources of seepage contaminated with raw slurry is high and would normally contain about 106 of each of total coliforms and faecal streptococci per litre (Hojovec, 1990, Moore at al., 1995). Flow of this FIO contaminated material will increase during rainfall events. 5.90 Diffuse pollution of FIO via the field drainage and run off, particularly from areas intensively grazed or after slurry application (Joy et al., 1998) can be another source of faecal micro-organisms with concentrations in excess of 104 coliforms per litre of drainage. Survey data presented in sections 5.1.14 and 5.2.14 indicate that some farmers spread manures in conditions likely to result in run-off. It has been shown that wet and cold soil can act as an reservoir of pathogens and despite a large soil retention of bacteria they can be washed out during storm conditions or can seep out under wet soil conditions (Svoboda et al. 1997). 5.91 On up to 50% of farms the grazing animals have access to watercourses and 13% of dairy herds in River Irvine catchment and 60% in the Water of Girvan catchment regularly cross the streams on a daily basis. Defecation directly to the water or in near proximity can contaminate water with large numbers of viable faecal micro-organisms in excess of 105 per gram of faecal material (Hojovec, 1990). The level of bacterial pollution in these streams and its contribution of the total bacterial load to bathing waters can be assessed by analyses of water and flow rates measured during the grazing period which coincides with the bathing season. 5.92 Human and animal faecal indicator organisms can be differentiated (Jagals et al., 1995, Parveen et al., 1999) and thus the contribution of agricultural practices to the pollution of bathing waters could be specified more accurately. This would elucidate the extent of actions required by the agricultural sector to minimise the dissemination of faecal organisms.
Farm operation and system factors and risks to watercourses 5.93 During the visits it was apparent that many farmers and contractors were unaware of the advice on good agricultural practices given in the PEPFAA Code. While a large number of farms used their common sense and experience to minimise problems, there was considerable evidence that watercourses were being put at risk from FIO contamination on some farms. The main
50
operational errors found on some farms are given along with the risk of water pollution and techniques to mitigate the problem and minimise risks (Table 5.2.5). 5.94 Waste minimisation and risk assessment, along with the Best Practical Environmental Option, should be fundamental to decisions on farm waste management. Waste minimisation application can bring about savings in energy and water use as well as a reduction in water pollution risks. The waste hierarchy provides a framework within which the most cost-effective waste management options are set out. The order of these hierarchy options is: • Reduction • Re-use • Recovery Risk assessment should be used as a criteria for ranking the suitability of land for manure application.
Pollution assessment 5.95 A more detailed assessment of the risk of water pollution was undertaken on a representative (and randomised) sub-sample of 20 farms. Out of these 20 farms assessed, a total of 18 had an apparent discharge leading to 'sewage fungus' in outfall watercourses and accumulation of solids manure discharge. The Control of Pollution Act 1974, as amended by Schedule 23 of the Water Act 1989, makes it an offence to cause or knowingly permit any poisonous, noxious or polluting matter to enter controlled waters: The following scoring system was used. Score 1 2 3
Meaning No or minimal discharge - would benefit by a little advice with negligible or no cost input. Discharge significant - could be prevented with limited expenditure and some management advice. Discharge significant - requires significant expenditure to reduce/cure problem together with management advice. Funding for expenditure is not apparently available on any of the farms visited in this score.
The results of this limited survey were as follows: Score 1 2 3
No. of Farms (Total = 20) 8 farms (40%) 9 farms (45%) 3 farms (15%)
51
Table 5.25 A summary of the main operational and system factors, relevant PEPFAA section, risks to watercourses and remedial guidance Operational/System (relevant section in PEPFAA code)
Risk
Remedial Guidance
1.
Clean rain water from roofs draining onto contaminated areas, drained into slurry and contaminated water storage (Section 3).
Increases volume of slurry to be handled. Reduces effective storage period Dilutes nutrient value.
Install, repair and maintain all roof water drainage systems where rainfall can become contaminated.
2.
Clean rain water from roads and aprons entering slurry and contaminated water storage (Section 3).
Increases volume of slurry to be handled. Reduces effective storage period Dilutes nutrient value.
Define clean areas and ensure all clean surface drainage is directed to appropriate clean outfall system.
3.
Poorly installed and maintained clean water drainage system allowing ingress of contaminated water and slurry (Section 3).
Contaminated discharge from clean drainage systems (Direct Risk to Potential Bathing Water).
Install, repair and maintain clean water drainage system to prevent ingress of slurry and contaminated water.
4.
Unroofed area used for stock feeding and access (Section 3).
Increases volume of slurry to be handled. Reduces effective storage period Dilutes nutrient value.
Rationalise use of unroofed areas to minimise area. Roof areas frequently used for stock standing or access in winter with full consideration to requirements for appropriate ventilation.
5.
Non containment of water contaminated by stock (Section 3).
Arbitrary and/or point discharge of contaminated water (Direct Risk to Potential Bathing Water).
Effectively minimise, intercept and contain all contaminated water. Subsequently handle in accordance with guidelines given in the PEPFAA Code Of Good Practice to avoid risk of pollution.
6.
FYM storage on constructed midden sites with/without roofing (Section 3).
Discharge from midden of contaminated drainage including rainfall (Direct Risk to Potential Bathing Water).
Intercept and collect all drainage. Minimise unroofed midden areas. Use of higher stacking can reduce surface area requirement for new middens. Handle all contaminated drainage in accordance with the PEPFAA Code Of Good Practice to avoid risk of pollution.
52
Operational/System (relevant section in PEPFAA code)
Risk
Remedial Guidance
7.
Surface and Equipment Washing (Section 3).
Contaminated water produced Uncontained drainage results in discharge of contaminated water (Direct Risk to Bathing Water). Containment results in increased pressure on existing storage systems reducing effective storage period.
Review alternative wash regimes to reduce water use Preclean surfaces to remove majority of 'solids'. Consider use of reduced volume wash equipment. Use trigger valves. Install a water meter to allow monitoring of water used and added to waste stream.
8.
Slurry and contaminated water storage availability (Section 3).
Insufficient capacity leading to risk of overflow and discharge (Direct Risk to Potential Bathing Water). Insufficient capacity leading to the requirement to empty stores frequently and land application in inappropriate conditions resulting in surface run off and ingress to field drainage (Direct Risk to Potential Bathing Water). With high capacity storage, large volumes of slurry/contaminated water applied to land in short 'time' envelopes over large areas may result in risk of run off and leaching to drains if post application conditions deteriorate (rain or thaw) (Direct Risk to Potential Bathing Water).
Minimise volumes of contaminated water and slurry to increase effective storage period. Calculate storage requirement and increase capacity. Prepare a Farm Waste Management Plan (FWMP).
9.
Slurry and contaminated water storage maintenance and operation (Section 3).
Poor maintenance and repair can result in gradual leakage and discharge of slurry and contaminated water (Direct Risk to Potential Bathing Water). Poor maintenance and repair can result in catastrophic structural failure and sudden release of stored slurry and/or contaminated water (Direct Risk to Potential Bathing Water). Poor maintenance and repair of store associated equipment can result in gradual or sudden release of slurry and contaminated water (Direct Risk to Potential Bathing Water). Poor operational management can result in store overflow (Direct Risk to Potential Bathing Water). Poor operational decisions can result in field applications being made in unsuitable conditions (Direct Risk to Potential Bathing Water).
Frequently inspect, repair and maintain storage structure and associated equipment. Ensure good operational management by use of competent person with appropriate training, knowledge and experience of the system and associated operations. Have and know contingency plans. Prepare a FWMP.
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Operational/System (relevant section in PEPFAA code)
Risk
Remedial Guidance
10.
FYM storage (Section 3).
Inappropriate material (flowable) being stored can result in direct discharge to drainage system. Inappropriate material (flowable) being stored can result in structural failure leading to gradual or catastrophic release of liquids (Low dry matter material and contaminated water). Inappropriate siting of constructed middens and field heaps can increase risk of arbitrary discharge to drainage (Direct Risk to Potential Bathing Water). Overfilling of constructed middens. Poor or absent collection facilities for contaminated water will result in discharge (Direct Risk to Potential Bathing Water).
Storage capacity should be adequate. Use an appropriately sited field heap to supplement storage rather than overfill. Install and maintain appropriate collection facilities for contaminated water collection and handling. Prepare a FWMP.
11.
Slurry and contaminated water transfer (Section 3).
Transfer equipment failure leading to leakage /overflow of slurry and/or contaminated water (Direct Risk to Potential Bathing Water). Operational management failure resulting in discharge of slurry and/or contaminated water (Direct Risk Potential to Bathing Water).
Ensure all equipment is appropriate and correctly installed with regard to its use. Ensure all operators are appropriately trained and in complying with recommended operational practice including Health and Safety issues. Prepare a FWMP.
12.
Requirement to contain all contaminated water (Section 3).
Overloading of existing storage facilities causing possible risk of overflow. Overloading of existing storage facilities causing requirement for land application in inappropriate conditions. (Direct Risk to Potential Bathing Water).
Minimise volumes of contaminated water and slurry to increase effective storage period. Calculate storage requirement and increase capacity of storage. Prepare a FWMP.
13.
Application of manures - planning of land availability (Section 4).
Shortage of available land can result in high application rates on limited areas leading to increased risk of run off, (Direct Risk to Potential Bathing Water). damage to land and wasted nutrient value. Overfilling increasing risk of overflow and redirection of contaminated water to drain (Direct Risk to Potential Bathing Water).
Prepare a FWMP, taking account of land availability and with regard to cropping and stocking. Ensure adequate area is available for safe application in accordance with the PEPFAA Code Of Good Practice.
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Operational/System (relevant section in PEPFAA code)
Risk
Remedial Guidance
14.
Application of manures at high application rates (Section 4).
Can result in run off and leaching to drains and watercourses (Direct Risk to Potential Bathing Water).
Application rate should be limited to crop nutrient uptake potential. Application rate should take account of application site risk appraisal, weather and field conditions. Maximum application should never exceed 50m³/ha. Always maintain a minimum exclusion zone of 10 m from any open watercourse.
15.
Application in inappropriate conditions (Section 4).
Can result in run off and leaching to drains and watercourses (Direct Risk to Potential Bathing Water).
Always apply manure/contaminated water in accordance with the PEPFAA Code Of Good practice. Take account of weather conditions before and during application. Take account of weather forecasting for reasonable post application period. Take account of field soil conditions. Take account of field cropping. Take account of previous applications. Take account of slope and factors which may affect run off potential. Maintain an exclusion zone of 10 m minimum to any open ditch or watercourse and increase this if appropriate.
5.96 The priority now is to effectively communicate these good agricultural practices and mitigation techniques to farmers. In the main the technical content of PEPFAA is satisfactory to protect watercourses and bathing water from FIO contamination. However further advice is required for certain topics e.g. contamination from feeding areas and heavily grazed areas and need to develop a graduated scale of maximum manure application rates based on slope, soil, weather conditions and time of application.
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CONTRACTORS SURVEY
Waste contractors operating in the Irvine and Girvan catchment 5.97 A total of 12 major agricultural contractors landspread wastes across both catchments. All contractors are working farmers, landspreading of being the main business diversification. The 12 contractors are based in the Irvine and Ayr catchments, no contractors are based in the Girvan catchment. 100% operate in the Irvine catchment and 55% in the Girvan catchment. To operate the waste contracting operations an average of four employees are actively engaged utilising the farm staff on a part-time basis. The largest waste contractor employs 10 staff on a part-time basis. 5.98 Most contractors and employees have no formal or vocational training in land or waste management. Two businesses have an employee trained at HNC and HND in Agriculture and Agricultural Engineering, whilst three businesses provide in-house training. Most contractors rely on subjective assessment i.e. ‘experience’ in minimising any pollution risk from waste application. 5.99 11 of the 12 contractors, and in most cases their employees, were interviewed in person. In all cases they were both co-operative and constructive in their responses and comments. Many contractors appreciate that there is a perceived or potential problem with poorly managed landspreading of wastes. Their specific comments are discussed in section 5.123. 5.100 All contracted waste application is charged on a time basis. Formal contracts are not established between contractors and farmer clients with no establishment of liability for pollution incidents resulting from operational failure or landspreading. One contractor attempted to establish a formal contract with a liability clause but this was rejected by a number of farmer clients and the idea was dropped on the advice of his lawyer. 5.101 Most contractors accept the need for training in risk assessment.
Compliance with legislation and codes of practice 5.102 Apart from one contractor spreading abattoir ‘gut’ waste, spreading operations are confined to farm manures. Sewage sludge and other non-agricultural wastes are not landspread by contractors in these catchments. Contractors were unaware of any governing legislation. Only 27% of contractors were aware of the PEPFAA Code, with only 18% actively following the Code and ensuring that employees complied with the Code. 60%, however, were familiar with SERAD Advice Note on the Safe Use of Animal Manures. 5.103 All contractors were provided with a copy of the PEPFAA Code but, based on their initial reaction, transfer of information would be more effectively achieved by a discrete guidance note specifically on this topic. 5.104 Contractors are not generally aware of current codes of practice on landspreading.
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Risk assessment 5.105 In most cases, it was first necessary to explain the concept of risk assessment. On 42% of farms some level of risk assessment was carried out prior to landspreading. 45% of the assessments were carried out by the contractor, 18% by the farmer and the remainder jointly. The criteria for field selection may be based on nutrient requirement rather than pollution risk. Table 5.26 Factors considered during field risk assessment Risk factor Soil type Field drains Ground conditions Slope Proximity of housing Watercourses - before application - during application - after application
Field assessed % 30 30 90 60 10 50 50 20
5.106 In almost all cases ground conditions dictate the land suitability for spreading (Table 5.26). This consideration is generally made on the suitability for machinery access rather than land suitability for waste application. The use of the umbilical system has allowed land access where soil conditions would prohibit slurry tankers. Some contractors will reject fields with unsuitable ground conditions against the wishes of the farmer client. 5.107 Slope is the second factor considered, with an appreciation of run-off problems and pollution risk. Some contractors only consider slope as a limitation to machinery access. Field drainage is assessed by 30% of contractors primarily by checking outfalls and watercourses before and during operations. Few check drain outfalls and watercourses on completion of spreading to ensure there is no residual pollution of drainage waters. Spreading adjacent to housing is not considered to be an issue but most contractors would apply manures to fields adjacent to housing if requested by the farmer. Only 60% of contractors leave 'exclusion zones' adjacent to watercourses, the average width being 5 m with a range from 2 to 20 m. 5.108 All contractors listen to the local weather forecast but 90% consider that it is not accurate enough to forecast suitable spreading conditions over the following few days. If not spreading locally, most contractors will contact the farmer to check on weather conditions at the spreading site. 5.109 It is important that risk assessments be used by all contractors on all landspreading sites.
Application systems 5.110 Normal tankers, low ground pressure tankers and umbilical systems are equally used by contractors with an increasing preference for umbilical systems to cope with soft ground conditions during the winter and spring months (Table 5.27).
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Table 5.27 Application equipment and handling rates Application system
Normal tanker LGP tanker Road tanker Umbilical Muck spreader
Total no.
Average no. per contractor
11 8 9 10 14
1 2 2 1 2
Handling rate (m³/hr) Average 39 49 127 38
Range 25-60 20-82 100-187 20-60
5.111 Tanker capacity averages 7 m³ for normal tankers and LPG tankers, all tankers and umbilical units being fitted with low-level splash plates to minimise drift. There is no application by injection. Umbilical systems can apply 3 times the rate of tanker systems and provided application rates are not exceeded, there is potential for maximising application in winter weather windows when ground conditions are suitable. Solid muck spreading is carried out by 80% of contractors using spreaders with an average capacity of 9 m³ (range 6-10 m³). Average handling rate per machine is 38 m³/hr. 5.112 If properly managed, umbilical systems will allow more slurries to be applied during the winter months i.e. outwith the bathing season.
Waste application planning 5.115 Waste application rates are set for 90% of all applications in the majority of cases (73%) by the farmer. These rates are followed in 80% of cases by the contractor, who will, in situations, adjust the rate after assessing the application site. On 20% of farms, rates are set by the contractor or the tractor driver and in a few cases there is agreement between the farmer and contractor. In most cases SAC's impression is that a similar rate is used on all land with some adjustment for soil, ground conditions and slope. There are no records kept by contractors on manure application rates, timing or landbank and as far as contractors are aware, only a mental record is kept by farmers. 5.114 It is surprising to record that only one contractor was aware of FMWPs, which was produced by one farmer. Land application schedules are only used occasionally by 5% of contractors. 5.115 FMWPs, initially produced mainly for manure application, should be enacted for land application planning.
Waste application in the Irvine and Girvan catchments 5.116 Contractors are used for slurry application on approximately 50% (260) farms in the Irvine catchment and 38% (34) farms in the Girvan catchment. For muck spreading the respective figures are 9% and 4% (Tables 5.28 and 5.29). On the majority of farms the contractor will do the main winter/early spring application of slurry when ground conditions are difficult. The farmer will carry out some of this application during the winter if soil conditions permit and will apply in early summer to grassland if time permits. Contractors predict an increase in their workload.
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5.117 As contractors are the major agents in waste management, the initial focus should be on this body if a cost-effective response to changes in landspreading practices is to be achieved. Table 5.28 Annual application of slurry by contractors in the Irvine and Girvan catchments Irvine 263 25 32,609 830 43* 15* 56*
Total farm units using a contractor Average units/contractor Average volume spread (m³) Average area spread (ha) Average application rate (m³/ha) Minimum application rate (m³/ha) Maximum application rate (m³/ha)
Girvan 34 7 7,940 193 41* 37.5* 53*
*Total annual application rates for either 1 or 2 applications – average rate per ha for each application will be lower as some of the land is spread twice.
Table 5.29 Annual application of FYM by contractors in the Irvine and Girvan catchments Irvine 55 6 4,922 124 40 18 79
Total farm units using a contractor Average units/contractor Average volume spread (m³) Average area spread (ha) Average application rate (m³/ha) Minimum application rate (m³/ha) Maximum application rate (m³/ha)
Girvan 4 2 750 15 50 50 50
5.118 With many contractors landspreading over large areas, Argyll to Dumfries, the number of farm units within the surveyed catchments is only the contractor’s estimate. This is obviously an overestimate, as is the total volume of manures, particularly slurries, spread within the catchment boundaries. As no spreading records are kept it is not possible to confirm this information. 5.119 Taking into account that annual application rates are based on either 1 or 2 applications, we can assume that rates per ha per application are in compliance with the PEPFAA Code and on average are well within the maximum recommended rate.
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Spreading season Table 5.30 Seasonal spreading of manures in the Irvine and Girvan catchments
January February March April May June July August September October November December Total
% Slurry Spread Irvine Girvan 10 16 12 19 27 23 16 11 3 0 8 0 4 6 1 0 0 0 6 7 7 7 7 11 100 100
% FYM Spread Irvine Girvan 0 0 0 0 29 25 37 60 6 0 0 0 0 0 0 0 20 15 5 0 3 0 0 0 100 100
Irvine 5.120 Most slurry is applied between February and April (55%), March being the main month of application. 70-80% of FYM is spread in March and April, April being the main month of application. 16% of slurries are applied during the bathing season in Irvine and 6% in Girvan with the May application being highest during a wet spring. 26% of FYM is spread during the bathing season in Irvine and 15% in Girvan (Table 5.30).
Girvan 5.121 To reduce any impact in the bathing season, consideration should be given to changing the PEPFAA Code to encourage winter application on frozen soils where there is no risk of run-off. This would reduce the volume spread during the bathing season. The impact of FIO bacteria, leaking from the manures applied to the land in March and April, on bathing water quality requires to be addressed in further studies.
Contractors’Comments 5.122 Contractors were asked if there were any particular issues or practices that would improve the landspreading practice and reduce the pollution risks.
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5.123 Responses: • Run-off is regarded as a particular problem when exceptionally heavy rainfall coincides with waste application even when ground conditions are suitable i.e. during the bathing season. This requires improved local weather forecasting. • Farmers should be engaging contractors to apply ‘little but often’over a longer season to avoid the ‘must empty when ground conditions are unsuitable’situation. • More forward planning is required by farmers when engaging contractors. Contractors could prioritise application between farmers on light and heavy land. • Reduce volume of dirty water into slurry stores by diverting clean water from contaminated areas. Slurry stores have inadequate capacity to store dirty water. • Bulk of application must be moved from the February/March period when soil conditions are unsuitable and pollution problems are predictable. • Waste storage is inadequate – restore grants to increase and improve storage. • Most contractors would not be against contractors being licensed to improve competence standards. • Muck spreading is regarded as having low pollution risk but run-off can occur during exceptionally heavy rainfall after high rates of application on sloping land. • Umbilical systems reduces soil damage but can increase pollution risk if not properly managed. Most contractors accept that umbilical systems with higher application rates and ready access to wet land have increased the pollution risk. • Farmers are not mixing slurry prior to landspreading. This results in dirty water being applied in the initial spreading and clean water being added to the slurry to dilute the residual slurry and allow application by umbilical systems. • Contractors are being blamed for pollution incidents when the problem is outwith their control, e.g. full stores have to be emptied at times when conditions are less than ideal and weather conditions are unpredictable. 5.124 In response to these comments, a number of these problems can be overcome by farmers in improved slurry/dirty water management, forward planning of landspreading programmes by farmers and contractors and improved operational procedures by contractors. It brings into question why FMWPs have been largely ignored by farmers and contractors in planning manure applications. 5.125 Many, if not all, contractors appreciate the potential pollution risk of winter landspreading but probably do not appreciate the knock-on risk to bathing waters by increasing waste application in the better months of April and May. In either situation risk assessment and land application planning must be encouraged.
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CHAPTER SIX CONCLUSIONS AND RECOMMENDATIONS 6.1 Livestock farming is the predominant land-use in both catchments which have above national average stocking densities. The River Irvine catchment consists of approximately 1.5% of the total agricultural land area of Scotland and yet has 15% of the total number of dairy cows in Scotland demonstrating the importance of this area to Scotland’s dairy industry. Beef and sheep numbers in the River Irvine catchment are approximately 3% of the Scottish total for both stock. The Water of Girvan catchment occupies approximately 0.5% of Scotland’s total agricultural area and has 1% of the beef cattle and 2% of the dairy and sheep stock in Scotland. 6.2 Both catchments have a high percentage (greater than 60%) of imperfectly and poorly drained soils on sloping land under high rainfall which require a risk assessment to be carried out prior to application of manure to minimise risk. 14% and 28% of the soils in the River Irvine and Water of Girvan catchments respectively are unsuitable for manure application. 6.3 Livestock farming inevitably produces manure which contains faecal indicator organisms (FIOs). Agricultural manures (solid and slurries) are valuable organic fertilisers and soil conditioners but may be sources of FIO pollution to watercourses if poorly managed. Seepage from fresh manure is reported in other studies to contain 10 6 of both total coliforms and faecal streptococci per litre. 6.4 In this study a survey of 117 farm site visits in both catchments highlighted a number of potential routes by which FIOs from farms could enter watercourses in the Irvine and Girvan catchments. 6.5
Faecal contamination of watercourses in both the Ayrshire catchments can be the result of: • Material transported into watercourses by non-collection, no containment or poor containment facility (leakage). • Surface run-off following land application of manure in unsuitable conditions (e.g. high rainfall during and following land application or grazing).
6.6 Point discharges of effluents or FIOs into watercourses can be expected from the majority of farms in both catchments. This mainly includes the leakage from uncontained middens, poorly designed or mis-managed waste storage facilities, high level slatted courts, self-feed silage aprons, farmyards and cow tracks. 6.7 Diffuse discharges of FIO via run-off and field drainage, particularly from areas of poorly managed slurry application and intensive grazing, can be another source of faecal micro-organisms with concentrations likely in excess of 104 coliforms per litre of drainage. Survey data indicated that up to 11% of farmers spread manures in conditions likely to result in run-off. 6.8 On up to 50% of farms, grazing animals have regular access to watercourses and on at least 13% of dairy farms, animals regularly cross watercourses on a daily basis. Defecation directly into water or in its near proximity can contaminate water with large numbers of viable faecal microorganisms. Loading in excess of 105 per gram of faecal material is likely.
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6.9 During the survey visits, it was apparent that many farmers and contractors were unaware of the advice given on good agricultural practices in the PEPFAA Code. Although a large percentage of farms used their ‘common sense’ and experience to minimise the risk of pollution problems, there was considerable evidence that watercourses were being put at risk of FIO contamination on some farms. 6.10 Contractors are engaged for slurry application on c. 50% of farms in the Irvine catchment and c. 38% in the Girvan catchment but are not generally aware of Farm Waste Management Planning (FWMP) and current Codes of Practice on landspreading. This lack of awareness gives cause for concern. 6.11 Septic tanks are used on practically all farms to treat farmhouse wastes. The majority of systems are old with a high proportion discharging directly to watercourses. Connection of other farm building drainage to the septic tank system occurs on some farms thus reducing the septic tanks effectiveness and increasing the potential risk of discharge of faecal material to watercourses. Septic tanks also commonly occur with non-agricultural dwellings and buildings in rural Ayrshire. 6.12 Although the survey highlighted potential sources of FIO discharges, little information is available on the magnitude, transit times and survival rates of FIOs from these point and diffuse sources. Further research work on this topic is recommended. 6.13 The main measures recommended to mitigate against the risk of FIO contamination of watercourses in the Ayrshire catchments are currently as follows: • Prevent contamination of clean water from roof and yard systems, with dirty water, to allow recycling or direct discharge of clean water to watercourses. • Reduce volumes of dirty water by minimising use of unroofed areas for waste storage, feeding and standing stock. • Consider alternative wash regimes to reduce water use. Pre-clean surfaces to remove 'solids' prior to washing and use low volume wash equipment. • Consider and minimise volumes of contaminated water when assessing slurry storage requirement in accordance with the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 1991. • Regularly inspect, repair and maintain storage structures and associated equipment. Ensure all equipment is suitable for use and correctly installed. Ensure contingency plans are available to all staff in the event of system failure. • Prepare and use an FMWP. • Always apply manure or contaminated water in accordance with the PEPFAA Code of Good Agricultural Practice. Comply with the recommendations as given in the FWMP, in particular the need for a minimum 10 m exclusion zone from watercourses and the assessment of suitable soil, field and weather conditions for landspreading.
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• Ensure farmhouse septic tanks are designed for their particular use and are correctly installed and monitored. • Site water troughs and feeding areas well away from watercourses and avoid regular stock movement on tracks where run-off to watercourses is likely. Where possible, stock should be prevented from standing in watercourses while drinking. Bank areas should be managed to prevent erosion by livestock. • Farmers and contractors should ensure good waste management operations by training staff to appropriate competence standards in the use of equipment and in the landspreading of wastes. 6.14 The priority now is to effectively communicate these good agricultural practices and mitigation techniques to farmers and contractors.
Recommendations 6.15 The study has identified some current agricultural practices and activities that create a risk of FIO contamination within the two catchments of Ayrshire. Little is known of the potential these sources have for FIO contamination of watercourses. The following additional work and research is therefore recommended: • Quantify the FIO load from the various sources within a farm taking into account the type of livestock enterprises (dairy, beef and sheep) and produce a budget of FIO sources and output magnitudes. • Characterise these sources in terms of their flow and potential FIO load delivery to watercourses. • Compare “within farm” FIO point source magnitude with estimates of FIO yield from diffuse farm sources such as field run-off. • Assess the likelihood of FIOs generated from farms in the Ayrshire catchments surviving downstream transport to the coast, using estimates from other studies. • Develop a graduated scale of maximum acceptable manure application rates based on slope, soil, ground and weather conditions and time of application. • Initiate a full awareness raising campaign for farmers and contractors in the Ayrshire catchments. Meetings should be held and action plans and guidelines produced for these farmers and contractors on cost-effective waste management measures to reduce the risk of FIO contamination to bathing waters.
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SAC (1995) Design and Construction Guidelines for farm waste storage. SAC Edinburgh. SAC (1999) Farm Management Handbook 1999/2000. SAC Edinburgh. SEPA (1998) Scottish bathing water report 1998. SEPA (1999) Scottish bathing water report 1999. SEPA (2000) Scottish bathing water report 2000. SOAEFD (1997) Prevention of Environmental Pollution from Agricultural Activity: SOAEFD, Edinburgh. Steffens, G and Lorenz, F (1993) Aspects of good agricultural practice in the application of organic manures. In: Scientific basis for codes of good agricultural practice (ed VWL Jordan) CEC Publication EUR 14957 EN, Brussels. Svoboda, I F, Read, I A., Kemp, J S, Wright, S E, Coop, R L., Mawdsley, J L, Bargett, R D., Merry, R J, Pain, B F, Theodorou, M K., Bukhari, Z, and Smith, H V (1997). Cryptosporidium on cattle farms. In. “Cryptosporidium in water - the challenge to policy makers and water managers”. Symposium by Chartered Institute of Water and Environmental Management, Glasgow, p.3-20. Tiedemann, A R, Higgins, D A, Quigley, T M, Saunderson, H R and Marx, D B (1987). Responses of faecal coliform in streamwater to four grazing strategies. J. Range. Manage. 40: 322-329. Vinten, A J A, Lewis, D R, Fenlon, D R, Leach, C, Howard, R Svoboda, I, and Ogden, I (2000) Survival and transport of E.coli and E.coli O157 in soils after cattle slurry application. Poster presented at the BSSS conference, Birmingham University, April 2000. Wyer, M, Crowther J, Kay, D and Fewtrell, L (1999) Faecal indicator organism sources and budgets for the Irvine and Girvan catchments, Ayrshire. Report to West of Scotland Water, SEPA and South Ayrshire Council, CREH, University of Wales, Aberystwyth.
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