Key for identifying categories of vineyard soils in ... - Land and Water

Key for identifying categories of vineyard soils in Australia

1 1

David Maschmedt, 2Rob Fitzpatrick and 3Alfred Cass

Dept. of Water, Land and Biodiversity Conservation, GPO Box 2834, Adelaide, SA 5001 CSIRO Land and Water, Private Bag 2, Glen Osmond, South Australia 5064 3 Alfred Cass & Associates, 1700 Maggie Avenue, Calistoga, CA 94515, USA. 2

Technical Report 30/02, August 2002

© 2002 CSIRO To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO Land and Water. Important Disclaimer CSIRO Land and Water advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO Land and Water (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it.


TABLE OF CONTENTS Summary

1

Rationale for developing the Viticultural Soil Key

1

Characteristics of the Viticultural Soil Key

2

The Viticultural Soil Key and Other Soil Classification Systems

3

Definitions of Morphological Descriptors used in the Viticultural Soil Key

3

Acknowledgments

6

References

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Table 1 Key for identifying categories and sub-categories of vineyard soils in Australia 8 Table 2 Interpreting Soil Consistence

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Table 3 Approximate correspondence between categories of vineyard soils in Australia and other soil classification systems 11 Table 4 Colour photographs of sub-categories of vineyard soils in Australia 16


Summary A user-friendly soil key was developed to identify soils in vineyards by people who are not experts in soil classification. It is based on a data set of soil properties that have relevance to grape production for most of the Australian rootstock trials across Australia. The soil identification key is an important tool for delivering soil-specific land development and soil management packages to grape growers. It can also help viticulturists select and match grapevine rootstocks to appropriate Australian soils. The soil key provides the means to describe Australian soils in terms of attributes meaningful to viticulture and to correlate these attributes with two local (Isbell 1996, Stace et al. 1968) and three international (Soil Classification Working Group 1991, FAO 1998, Soil Survey Staff 1999) general-purpose soil classification systems. The key uses nontechnical terms to categorise soils in terms of attributes that are important for vine growth. The soil features used in the key are easily recognised in the field by people with limited soil classification experience. The following viticulturally important and mostly visual diagnostic features were used: depth to certain characteristic changes in wetness (waterlogging), consistency, colour, structure, calcareousness in different restrictive layers, cracking, texture trends down profiles (e.g. texture contrast at A/B horizon boundary or duplex character). The key layout is bifurcating, based on the presence or absence of the particular keying property, which is usually a diagnostic property. The soil key consists of a systematic arrangement of soils into 9 broad categories and 36 subdivisions or sub-categories.

Rationale for developing the Viticultural Soil Key The soil identification key was developed to provide the viticulture industry with a language to facilitate communication about soils used for wine grape production. The key uses, as far as is possible, non-technical language to categorise soils in terms of attributes that are important for vine growth. The basic philosophy of the key is strongly linked to issues of viticultural soil management (e.g. Cass 1999, Fitzpatrick et al. 1993). However, as a tool for understanding wine production historically within Australia and in other wine-producing countries, the key needs also to correlate with previous and current Australian and international soil classification schemes. Several different soil classification systems have been or are used in Australia (Stace et al. 1968; Northcote 1979; Isbell 1996) and in overseas countries that produce wine (Soil Survey Staff 1999; USDA Soil Taxonomy and Soil Classification Working Group 1991; Soil Classification: A Taxonomic System for South Africa, 1991; FAO World Reference Base for Soil Resources 1998). All these general-purpose classification systems lack user-friendly keys for identifying soil profiles by people who are not experts in soil classification. It was clear from their lack of use in Australia, that the existing general-purpose systems were not suitable because they are too technical or complex. Viticultural information in Australian and overseas literature, based on soils classified using general-purpose soil classification systems could often not be applied correctly to Australian conditions, because there was no means to link these identifiers to local understanding of the nature and properties of soils. Australian and international general-purpose classification systems were found to be too complex for identifying soil profiles in vineyards by people who are not experts in soil classification. The Australian viticulture industry called for the development of a userPage 1


friendly soil key, which could be used by viticulturists to help select and match grapevine rootstocks to appropriate Australian soils (May 1993, 1994). In both these papers, May states " … the choice of the most suitable rootstock may not be possible until we know more about the way in which rootstocks interact with the soil environment on the one hand and with their scion on the other hand". Other uses for the key were foreseen, for example, as a tool to correlate grower knowledge about their soils with other soils classified using these more technical systems. The primary aim of such a user-friendly soil key will be to identify categories of vineyard soils, using soil features that are associated with the main soil types occurring in viticultural regions of Australia. The soil features used in the key should be easily recognised in the field by people with limited soil classification experience. The key layout should be bifurcating, based on the presence or absence of a particular keying property, which is usually a diagnostic property. The concept to be used in the key should be similar to the user-friendly keys compiled for soils in Western Australia (Schoknecht 2001) and Fitzpatrick et al. (1997, 2001, 2002b) to solve practical soil related problems.

Characteristics of the Viticultural Soil Key In the system described here, we have developed a simple soil key to assist viticulturists to categorise visual soil properties into a system for naming soils used for wine growing in Australia. In developing the Soil Key we used soil descriptions and soil chemical data contained in the Rootstock Soil Properties Database, which consists of 132 characterised viticulture soils from rootstock trials across Australia (Cass et al. 2002a, b). We focussed on the following viticulturally important and mostly visual diagnostic features: changes in wetness (waterlogging), consistency, colour, structure, calcareousness in different restrictive layers, cracking, texture trends down profiles (e.g. texture contrast at A/B horizon boundary or duplex character). The key layout is bifurcating and based on the presence or absence of the particular keying property, which is usually a diagnostic property (Table 1). Broad groupings (i.e. 9 categories) are made on the basis of general characteristics such as waterlogging, depth different restrictive layers (e.g. shallowness and stoniness), presence of cracking and slickensides, texture trends down profiles (e.g. texture contrast at A/B horizon boundary or duplex character) and calcareousness. Subdivisions (i.e. 36 sub-categories) are made on the basis of more detailed differences in specific properties (consistency, colour, structure, calcareousness). Between 1997 and 2002, this key went through several stages of development (e.g. Fitzpatrick et al. 2002a) and has been successfully tested on many viticultural soils throughout Australia. The terminology used is a combination of that used by McDonald et al., (1990), Stace et al. (1968), Northcote (1979), Isbell (1996), Soil Survey Division Staff (1993) and summarised in Fitzpatrick et al. (1999). This reflects common usage in Australia where soil might be referred to as either "texture contrast" (duplex, with abrupt change from a coarse to medium textured surface layer to a more clayey subsurface layer, "uniform" (little change in texture down the profile) or "gradational" (gradual increase in texture down the profile), “cracking clay”, and/or “calcareous”. These terms have been found to be useful in field applications. In particular, in the key we have paid attention to identifying "potential soil constraints", such as easily identifiable restrictive soil layers that might limit effective root depth (Table 1). We also use observations of depth to certain characteristic changes in waterlogging (mottles or watertables), consistency, colour, Page 2


texture and structure in different restrictive layers. Each soil category is provided with a listing of possible qualifiers in a priority sequence. The process of identifying soils in the field is facilitated by providing colour photographs of most of the 36 soil sub-categories in the soil key (Table 4). In conjunction with this key the "broadscale" soil maps of the viticultural regions of Australia could also be used to help with the identification of viticultural soil types (Fitzpatrick et al. 1993). A more extensive period of validation will occur over the next few years.

The Viticultural Soil Key and Other Soil Classification Systems One of the main objectives in developing practical attributes was to build the key in such a way that it uses knowledge and experience of many soil scientists in Australia and from all over the world. In Table 3 we have identified as closely as possible, corresponding classes in the following systems: • The Australian Soil Classification System (Isbell 1996). • Great Soil Group Classification (Stace et al. 1968). • Soil Taxonomy (Soil Survey Staff 1999). • A Taxonomic System for South Africa (Soil Classification Working Group 1991). • World Reference Base for Soil Resources (FAO 1998).

Definitions of Morphological Descriptors used in the Viticultural Soil Key Morphological descriptors are used for assessing soil conditions. These are: 1. Presence of a ground water table: free water at a particular depth in the soil. 2. Colour: This is the most readily identified morphological characteristic. While the presence and form of iron oxides (red and yellow) and organic matter (dark colours) are the main features determining a soil's colour, it can also be influenced by other minerals such as calcium carbonate (pale colours). Colour is often used to identify horizon changes down a profile. It can also provide an indicator of the soil's organic matter content and fertility levels, as well as redox condition, which relates to soil aeration (drainage). Dark brown or black colours typically result from high organic matter content. High chroma red and yellow colours are usually found where iron minerals are present in oxidizing conditions. Properties influenced by coloured iron oxides include retention of anions such as phosphate. Uniform bright red colours usually indicate good drainage. Pale colours indicate the absence of iron oxide, often due to its removal through leaching or reduction. Mottles - spots, blotches, or streaks of colour subdominant to the matrix colour commonly indicate impeded drainage. Patches of red, orange or yellow in a pale matrix are concentrations of iron oxides formed by redistribution during periodic waterlogging. 3. Gley (bluish or greenish grey) colours (low chroma) are often found in severely waterlogged conditions where reduction is almost complete. Gleyed - a soil condition resulting from prolonged soil saturation, which is manifested by the presence of grey or bluish or greenish pigmentation through the soil mass or in mottles (spots or streaks). Gleying occurs under reducing conditions in which iron is reduced predominantly to the ferrous state. Page 3


4. Segregations: discrete accumulations of material by chemical or biological processes (e.g. carbonate, ironstone and gypsum). 5. Coarse (rock) fragments: comprise all strongly cemented soil materials, including rock fragments and hard segregations, which are sized greater than 2 mm. They are subdivided into fine gravels (2 to 6 mm), medium gravels (6 to 20 mm), coarse gravels (20 to 60 mm), cobbles (60 to 200 mm), stones (200 to 600 mm) and boulders (>600 mm). High amounts of coarse fragments in the soil may impose severe limitations on its capacity to supply water and nutrients by reducing volume of soil available for root activity. They can also have an adverse impact on soil workability, being highly abrasive to tillage implements. On the other hand, surface gravel may reduce erosion, act as a mulch to reduce evaporation from the soil, and store heat for re-radiation during the night. 6. Soil consistence - is a measure of the strength and coherence of a soil. Soil consistence is also called rupture resistance and is a very readily observed feature in the field. In viticulture, this morphological attribute gives an indication of potential for root impedance. Factors that influence consistence include soil texture, mechanical compaction, aggregation, organic matter content and cementing agents. Soil consistence can be very readily measured in the field by determining the magnitude of finger, foot or hammer force needed to cause disruption or distortion to a 25 to 30 mm block of soil. See simplified definitions and tables in Fitzpatrick et al (1999). The depth of likely root penetration in soils can be estimated in the field by measuring changes in soil consistence progressively down the soil profile from the soil surface (e.g. Tables 1 and 2 – in Fitzpatrick et al 1999). The very hard and rigid classes are often indicative of reduced permeability as well. Classes of consistence are defined in Table 2 in Fitzpatrick et al 1999. The table is re-presented in this paper, also as Table 2. 7. Soil texture - relative proportions of sand, silt and clay in the soil. Soil texture (field method) - is determined in the field by the following procedure: Take a sample of soil sufficient to fit comfortably into the palm of the hand (separate out gravel and stones). Moisten soil with water, a little at a time, and work until it just sticks to your fingers and is not mushy. This is when its water content is approximately at "field capacity". Continue moistening and working until there is no apparent change in the ball (bolus) of soil. This usually takes 1-2 minutes. Make a ribbon by progressively shearing the ball between thumb and forefinger. The behaviour of the worked soil and the length of the ribbon produced by pressing out between thumb and forefinger characterises 15 soil texture grades as shown in (McDonald et. al., 1990).

8. Texture Groups (according to Northcote, 1979): The Sands = sand (S), loamy sand (LS), clayey sand (CS). The Sandy Loams = sandy loam (SL). The Loams = Loam (L); sandy clay loam (SCL); Silty loam (ZL). The Clay Loams = Clay loam (CL). The Light Clays = light clay (LC). The Medium-Heavy Clays = Medium clay (MC), Heavy clay (HC).

9. "Duplex" texture: contrast in texture between the topsoil and subsoil that is greater than 1 ½ the Texture Groups defined under “Texture Groups” above, e.g.: Sand/clay Sand/sandy clay loam Loam/clay Loam/clay loam/medium or heavy clay.

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10. Uniform texture: very little contrast in texture between layers in the profile, e.g.: Sand/sand/sand Clay loam/clay loam/clay loam Clay/clay/clay.

11. Gradational texture: steady increase in clay down the soil profile, e.g.: Sand/loamy sand/sandy loam Loam/clay loam/clay Clay loam/clay/medium clay.

12. Soil Structure - relates to the way soil particles are arranged and bound together. It can be described from the visible appearance of in-situ soil in a dry to slightly moist state. The size, shape and nature of soil aggregates play a major role in determining profile hydrology and the ease of root penetration. Where soil particles are bound together in natural forming aggregates (peds) separated by irregular spaces, the soil is described as having structure. The degree and nature of structure development is largely determined by clay mineralogy and organic matter content. Where peds are absent, the soil is described as being uniform or structureless. In a single-grained material, the soil is loose and incoherent. In a massive material, it is structureless and coherent. Soils that are single-grained or have moderately to strongly developed small peds, tend to be well aerated and freely drained. Plant roots grow easily through these soils and water infiltrates readily. Where the soil is composed of accommodated (ie close-fitting) peds, there are often restrictions to penetration of roots, air and water, and drainage may be poor. Similar problems can be experienced in massive soils, depending on the soil texture and consistence. 13. Blocky, prismatic, columnar structure: distinct structural character with clear planes of weakness between each ped and with equi-dimensional, sharp angled, accommodating sides (blocky) or vertical dimensions greater than horizontal but with rounded tops (columnar) or flat tops (prismatic). 14. Well structured: consistence that is firm or weaker in moderately moist condition and does not have columnar, prismatic or course blocky structure but rather more spherical, non-accommodating peds. 15. Slickensides: Natural shiny surfaces found on soil aggregates formed by the parallel orientation of clay particles during swelling and shrinking cycles. Refers to polished or grooved surfaces within soils resulting from part of the mass sliding or moving against adjacent material along a plane that defines the extent of the slickensides. In soils, they only occur in clay rich materials with high swelling clay content. 16. Topsoil: the surface layer of the soil, generally but not always darkened by accumulation of organic matter. 17. Subsoil: the subsurface layer, lacking in organic matter and generally coloured by secondary accumulations of iron, clay, carbonate, etc. 18. Calcareous: reaction of the soil to a drop of hydrochloric or other acid (indicates the presence and possibly amount of free carbonate present). 19. Rippable vs. non-rippable rock: rock which can be ripped has potential for supporting some root growth. This characteristic is particularly important in shallow soils. 20. Calcrete (calc-rock): hard, rigid limestone or carbonate-rich soil material. 21. Restrictive layer: layer, which impedes root growth. Includes non-rippable rock or hardpan, clayey material with prismatic, columnar or coarse blocky structure, or waterlogged soil, as indicated by gley or dull grey colours.

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In addition to the above attributes a set of modifiers can be used to further refine soil classes. Modifiers are properties that cannot be determined in the field but require laboratory intervention. The modifiers are determined on samples taken from soil layers within the soil profile. They are used to designate any soil category as, say, “Saline” or “Sodic” or “Acid” (Cass et al. 1996). Morphological descriptors combined with modifiers are useful in assessing soil conditions because they assist in diagnosing possible constraints to vine growth and they can be used in research to evaluate causes for variation in soil condition induced by land management, hydrology and weather conditions. The principle modifiers used in this key are: • Soil reaction: the pH of a 1:5 soil to water extract. • Salinity: the amount of salt in the soil as measured by electrical conductivity of a 1:5 soil to water extract. • Sodicity: the relative proportion of sodium to calcium and magnesium in a 1:5 soil to water extract.

Acknowledgements This research was partly supported with contributions from Grape and Wine Research and Development Corporation Project CRS 95/1. The authors are grateful to the following members of the respective state departments of agriculture and other organisations for providing access to and help and information on the Australian rootstock trials: South Australia: Mr. P. Nicholas and Dr. M. McCarthy; Victoria: Mr. John Whiting; New South Wales: Mr. T. Somers and Mr. H. Creasey; Western Australia: Mr. J. Campbell-Clause; Other experimental sites: Dr. R. Walker (of CSIRO Plant Industries) in South Australia and Victoria and Mr. P. Sinclair in New South Wales.

References Cass A. (1999). What soil factors really determine water availability to vines. The Australian Grapegrower and Winemaker, Annual Technical Issue, pages 95-97. Cass Alfred, Robert Fitzpatrick, Karin Thompson, Andrew Dowley and Susan Van Goor (2002a). Rootstock Trial Soil Properties. In: Alfred Cass (ed) ‘Sustainable viticultural production: Optimising soil resources. Final report (CRS 95/1) to Grape and Wine Research and Development Corporation (GWRDC). Cass Alfred, Robert Fitzpatrick, David Maschmedt, Karin Thomson, Andrew Dowley and Susan Van Goor. (2002b). Soils of the Australian Rootstock Trials. The Australian and New Zealand Grapegrower & Winemaker (Annual Technical issue). vol. 461A. p.4049. Cass A., R.R. Walker and R.W. Fitzpatrick (1996). Vineyard soil degradation by salt accumulation and the effect on the performance of the vine. p. 153-160. In: C.S. Stockley, R.S. Johnstone and T.H. Lee (eds.). Proceedings of the 9th Australian wine industry technical conference; July, 1995; Adelaide, South Australia. Winetitles. FAO (1998). The world reference base for soil resources (WRB) World Soil Resources Report No. 84. Food and Agriculture Organisation for the United Nations (FAO)/ISSS/AISS/IBG/ISRIC, Rome, 1998. Fitzpatrick R.W., J.W. Cox, and J. Bourne (1997). Managing waterlogged and saline catchments in the Mt. Lofty Ranges, South Australia: A soil-landscape and vegetation key with on-farm management options. Catchment Management Series. CRC for Soil and Land Management. CSIRO Publishing, Melbourne, Australia, 36 pp. ISBN 1 876162 30 9. Page 6


Fitzpatrick Robert, David Maschmedt and Alfred Cass (2002a). Australian Viticultural Soil Key. In: Alfred Cass (ed) ‘Sustainable viticultural production: Optimising soil resources. Final report (CRS 95/1) to Grape and Wine Research and Development Corporation (GWRDC). Fitzpatrick R.W., J.W Cox, B. Munday, and J. Bourne (2002b). Development of soillandscape and vegetation indicators for managing waterlogged and saline catchments. Australian Journal of Experimental Agriculture: Special Issue featuring papers on “Application of Sustainability Indicators” (In press). Fitzpatrick R.W., N.J. McKenzie and D. Maschmedt (1999). Soil morphological indicators and their importance to soil fertility. p 55-69. In K. Peverell,, L.A. Sparrow and D.J. Reuter (ed.) In Soil Analysis: an Interpretation Manual. CSIRO Publishing, Melbourne, Australia. Fitzpatrick R.W., P.M. Slade, and P. Hazelton (2001). Chapter 3 - Soil-related engineering problems: identification and remedial measures. p. 27-36. In V. A. Gostin (ed.) Gondwana to Greenhouse: Australian Environmental geoscience. Geological Society of Australia Special Publication 21. GSA, Australia. Fitzpatrick R.W., M.J. Wright and R.M. Stevens (1993). Drainage, sodicity and related problems of vineyard soils. p. 38-44. In: C.S. Stockley, R.S. Johnstone, P.A. Leske and T.H. Lee (eds.). Proceedings of the 8th Australian wine industry technical conference; 25- 29 October, 1992; Melbourne, Victoria. Winetitles. Isbell R.F. (1996) The Australian soil classification system. CSIRO, Publishing, Melbourne, Australia. May P. (1993) Review of rootstock use in Australia. In Vineyard development and redevelopment. Proceedings of a seminar organised by the Australian Society of Viticulture and Oenology, Inc. and held on 23 rd July, 1993. Mildura, Victoria. Ed Peter Hayes. Pages 42-43 and continued on page 48. May P. (1994). Using grapevine rootstocks: the Australian perspective. Winetitles, Adelaide, South Australia. McDonald, R.C., Isbell, R.F., Speight, J.G., Walker, J. and M.S. Hopkins, (1990). Australian soil and land survey field handbook. 2nd Edition, Inkata Press, Melbourne. Northcote, K.H. (1979). A Factual Key for the Recognition of Australian Soils. 4th Ed. (Rellim: Adelaide). Schoknecht, N.R. (ed.) (2001). Soil Groups of Western Australia. Resource Management Technical Report 193. Agriculture Western Australia, Australia. Soil Survey Staff (1999). Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys. 2nd edition. Agriculture Handbook No. 436. United States Department of Agriculture, Natural Resources Conservation Service, Washington. pp 869. Soil Survey Division Staff (1993). Soil Survey Manual. United States Department of Agriculture Handbook No. 18. (U.S. Government Printing Office, Washington, DC). Soil Classification Working Group (1991) Soil Classification: A Taxonomic System for South Africa. Memoirs on the Agricultural Natural Resources of South Africa No. 15. pp. 257. Stace, H.C.T., G.D. Hubble, R. Brewer, K.H Northcote,. J.R. Sleeman, M.J. Mulcahy, and E.G. Hallsworth, (1968). A Handbook of Australian Soils. Rellim: Glenside, South Australia.

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Table 1: Key for identifying categories and sub-categories of vineyard soils in Australia Does the soil have one of the following diagnostic features? a water table within 50 cm of the surface for three months of the year. or grey subsoil layers that may have yellow and/or reddish mottles.

Soil Category

Sub-category

1: Wet Soil

Can soil be drained? NO? ↓ Un-drainable wet soil

1

YES? → Wet drainable - continue below↓

YES? →→→→→→→→→→→ NO?↓ is less than 15 cm deep (or