peat, hemp, linen, sawdust, shredded newspaper and the mixtures, peat/wood chips, peat/sawdust, and peat/straw. Peat and peat mixtures had the best quality ...
Refereed
QUALITY OF DIFFERENT BEDDING MATERIALS AND THEIR INFLUENCE ON THE COMPOSTABILITY OF HORSE MANURE S. Airaksinen, MSc1; H. Heinonen-Tanski, PhD2; M-L. Heiskanen, PhD1
SUMMARY The air quality of the stable and management and composting of manure can be improved by choosing bedding material with certain desirable properties. The optimal bedding material doesn’t cause hygiene problems in the stable. It absorbs ammonia, is economic in use, and decomposes quickly with manure. The objective of this trial was to compare both quality of different bedding materials and their influence on the composting process of horse manure. Bedding materials used in the study were wood chips, straw, peat, hemp, linen, sawdust, shredded newspaper and the mixtures, peat/wood chips, peat/sawdust, and peat/straw. Peat and peat mixtures had the best quality of ammonia absorption, water holding, and manure fertilization value. The number of fungi and bacteria were lower in shredded newspaper and wooden materials than in straw, linen, hemp, and peat. The composting temperature became high enough for at least a partial destruction of parasites and seeds within the rubbish heaps in all boxes. Only peat manure was ready for further plant production after one month’s composting period. Other bedding materials were decomposed only partially or not at all during the study. INTRODUCTION Problems with stable hygiene may often be linked with bedding material used in the stable. Bedding has effects on indoor air, and the volume and quality of manure removed Authors’ addresses: 1Equine Information Centre, Hingunniementie 98, FIN-74700 Kiuruvesi, Finland. 2Department of Environmental Sciences, University of Kuopio, PO Box 1627, FIN-70211 Kuopio, Finland. Acknowledgements: The authors are most grateful for the support during this work given by the Horse College of Kiuruvesi and professor Pekka Mäenpää from the University of Kuopio.
Volume 21, Number 3, 2001
from the box stall. In Nordic climates, the storage of manure must be done for up to nine months of the year, resulting in high storage and disposal costs. The whole chain of manure to field should be done so that utilization of manure can be environmentally accepted. Ammonium gas, dust and biological aerosols reduce the quality of indoor air and increase the possibility of respiratory diseases. Bedding is known as a major source of fungal spores along with hay in the stable.1 Straw may contain greater respirable dust than wood shavings, paper,2 and sawdust.3 The ammonia concentration in indoor air depends on the quality and amount4 of bedding material and manure management conditions.5, 6, 7 A good manure management system is hygienic, easy to accomplish technically, economical and without negative environmental effects. Manure should be able to be exploited; for example, as a fertilizer or soil improvement material after treatment and storage. Because of constrains on the storage capacity for manure, the time used for manure treatment and storage should be as short as possible. Bedding materials such as recycled phone book paper, sawdust, and straw have been noticed to decompose poorly during two months’ composting process.8 Differences have been found in the process temperatures during composting of dirty phone book paper, sawdust, straw, and wood shavings, which may affect the hygiene of the compost product.8, 9 The purpose of this study was to study how different kinds of bedding materials influence stable hygiene and composting of horse manure. MATERIALS AND METHODS Ten bedding materials used in the study were, wood chips, straw, sphagnum peat, hemp, linen, sawdust, shredded newspaper and mixtures (3:1), peat/wood chips, peat/sawdust, 125
and peat/straw. Straw used was cut up to 10 cm strips for the mixtures. The main qualities of ammonia absorption, water holding capacity and hygienic quality of bedding material were studied with wood chips, straw, peat, hemp, linen, sawdust, and shredded newsprint paper. The statistical treatments for the qualities of ammonia absorption and water holding capacity were done with the non-parametric Kruskal-Wallis Test. Materials mentioned above were used in a bedding study in a stable with 16 horses. Each bedding material was tested with four horses. The manure produced in bedding was collected into the composting boxes. Both studies were conducted during two periods, first in July 26 – Sept. 3 1998 and second in Oct. 2 – Nov. 5 1998. Outdoor temperature during those studies is shown in Fig. 2 and Fig. 3. Ammonia absorption and water holding capacity Ammonia absorption capacity was measured with Dräger diffusion tubes (NH3 20/a-D)a placed in a plastic bag including 200 ml bedding material (measured with loose bedding) and 800 ml fresh horse urine. Measurement (n=2) was done after two hours’ incubation at +17.4oC. Total concentration of ammonia in the plastic bag was measured with 0.8 dl of pure horse urine (n=2). Ammonia absorption capacity of bedding material was calculated by the following equation: (T-c/t) A= ---------- *100%, where T A= absorption capacity of material (%), T= total concentration of ammonia in a plastic bag with pure horse urine (ppm/h), c= concentration of ammonia in a plastic bag with bedding material and urine (ppm), and t= time of incubation (h). Water holding capacity of bedding material was measured in a barrel with strainer bottom (V=10 liters). The barrel was placed on a larger collecting vessel. One liter of bedding material and two liters of water were added to the barrel, and the water passing through the strainer was collected and measured one hour later (n=3). Water was added to the barrel by pouring it from a can. Bedding material was wet before straining was started. Measurements were done at room temperature. Hygiene quality of bedding materials Hygiene analyses of bedding materials were done by Kuopio Regional Institute of Occupational Health.b Microbes (mesophilic fungi, xerophilic fungi, thermotolerant fungi, mesophilic bacteria and thermophilic actinomycetes) were determined with five growth media. Numbers of colony forming units (cfu) were counted after incubation and identified microscopically. 126
Management and composting The box stalls (about 3x3 m2 each) were cleaned daily during the bedding study. Feces and bedding with urine were removed into the composting boxes during a week. Removal of clean bedding was avoided. Composting in a wooden box with a cover (1 m3) (Fig. 1) and fertilization value after composting were studied from manure with wood chips, long straw, peat, hemp, shredded newspaper, peat/wood chips, peat/sawdust, and peat/straw. After a one-week period of manure collection, measurement of temperatures from the composting mass was started. Temperature was measured once a day (in the morning) for 34-35 days. Measurements were done in depths of 10 cm, 22 cm (n=4) and 30 cm (n=2) from the top of the composting mass. Samples for nutrient analysis were collected from a depth of 10 – 20 cm from the top of the composting mass zero days, three weeks, and six weeks after starting the composting study. The total potassium, total phosphorus, soluble nitrogen, dry matter, and content weight (kg/m3) of the bedding manure were analyzed by Soil Analysis Service.c Biological activity of the composting mass, including the number of mold colonies, formation of mushrooms and flies was visualized daily. The number and vitality of rubbish heap seeds in composted manure was studied with a simple germination test, where bedding manure samples after different times of composting were taken into the room temperature, seeded and moisturized for ten days. After 27 or 28 days of composting the masses were turned totally upside down. That was done to avoid the further decrease of the composting temperature caused by the lack of oxygen or moisture in the mass. RESULTS AND DISCUSSION There were significant differences in ammonia absorption
Figure 1. Composting boxes with open covers. JOURNAL OF EQUINE VETERINARY SCIENCE
Table 1a. Relative ammonia and water holding capacity of different bedding materials Bedding Material
Peat moss Linen Sawdust Hemp Shredded newspaper Wood chips Straw Total
Relative ammonia absorption at +17.4°C (%) Mean (n=3) Std. Deviation (n=3) 100 0 76 0 64 0 60 0 52 0 44 11.1 4 11.3 22.4
Water holding capacity (1 of bedding/capacity at 10 liter of water) at room temperature Mean (n=3) Stardard Deviation (n=3 14.8 0.97 19.0 1.40 9.7 0.28 22.5 0.53 27.2 3.43 31.9 3.72 69.7 10.01 27.8 19.23
Table 1b. Test statisticsa,b,c in ammonia absorption capacity and water holding capacity.
Chi-Square df Asymp. Sig. Exact Sig.
Relative ammonia absorption capacity at +17.4°C 12.855 6 0.045
