EQUINE BEDDING MATERIALS EFFECT ON PHYSICAL AND CHEMICAL PROPERTIES OF COMPOSTED STALL WASTE ABSTRACT In recent years new bedding materials have been marketed to the equine industry. Limited research has been conducted to evaluate how composting impacts the physical and chemical properties of these materials. In 2010, a study was conducted to evaluate the effects that bedding materials have on the physical and chemical properties of composted equine stall waste. Two bedding materials were evaluated including a pelletized straw product and wood shavings. Differences were observed in final mass, organic matter, particle size distribution and several chemical parameters. Composting resulted in significant reductions in final C:N ratio for all bedding materials with the greatest reductions occurring in the straw-based material. Bedding materials appear to influence the physical and chemical properties of composted equine stall waste and can have dramatic impacts on the potential of using composted equine stall waste as a soil amendment. INTRODUCTION A typical 455 kg (1,000 pound) horse produces 0.023 m 3 (0.82 ft 3 ) of manure per day weighing more than 22.7 kg (50 pounds). In addition to manure, equine stall waste includes various bedding materials such as straw or wood shavings. The amount of bedding added varies based on individual management, but has been found to range from 2.7 kg per day for wood shavings to more than 3 kg per day for straw (Komar, 2009). Disposal of this waste material can be an issue, particularly on small farms with limited available acres for spreading manure. Recently, composting of this waste material has been suggested as a potential handling technique for small equine operations. Much of the research comparing bedding materials’ impact on compost quality has been conducted using beef and dairy waste. Limited research has been conducted to evaluate the impact that bedding materials have on the chemical and physical characteristics of composted equine stall waste. MATERIALS AND METHODS A study was conducted at the Rutgers Equine Science Center in New Brunswick, New Jersey to evaluate the chemical and physical characteristics of two common equine stall bedding materials following an aerated composting process. The bedding materials included a pelletized wheat straw product and pine wood shavings. Compost piles were constructed on May 12, 2010. Four replications of each of the bedding materials were constructed and placed in a randomized complete block design for statistical analysis. Digital thermocouples were used to monitor the temperature in the center of each pile during composting. Physical and chemical properties of the compost were evaluated using conventional laboratory procedures at the beginning (day 1) and end of the composting process (day 100). Data were subjected to analysis of variance and means separated using Fisher’s LSD (P=.05). RESULTS AND DISCUSSION All materials reached maximum temperatures during the first weeks of composting. Among materials, only the pelletized straw maintained temperatures above 55°C . This is in compliance with USEPA guidelines for microbial decline of at least 15 days at 55°C. Temperatures were below this threshold for the remainder of the experiment (Figure 1) reaching temperatures near ambient by the conclusion of the trial. Composting resulted in significant mass reductions for both bedding materials with numerical differences observed between the straw and wood materials ( Figure 2.). Organic carbon was reduced during composting for both materials suggesting that composting occurred for both treatments (Figure 3.). Differences were observed in available P with concentrations increasing for both materials (Figure 4.). No differences were observed in K concentration following composting (Figure 5.). TKN was greater in the pelletized straw material following composting (Table 1.). Differences were observed in nitrate-N following composting with the greatest increase occurring in the pelletized straw. Particle size was reduced for both materials following composting suggesting that organic C was degraded during composting (Table 2.) CONCLUSIONS As the equine industry continues to expand in New Jersey, manure management will continue to be an important component of a well-managed equine operation. Farms with limited acres will need to maximize the effectiveness of their manure applications to ensure maximum crop yield while minimizing the potential for environmental impact. Composting horse stall waste appears to be a promising manure management strategy by reducing manure volume while providing crop nutrients. Bedding type appears to impact volume, as well as, the physical and chemical characteristics of composted equine stall waste. More research is needed to quantify the effectiveness of alternative bedding materials and to determine their acceptance by the equine consumer. Komar*, S.J. 1 ,Williams, C. 2 , Westendorf, M. 3 , Miskewitz, R. 4 Mickel, R.C. 5 ,Bamka, W.J. 6 1 Extension Agent, Rutgers Cooperative Extension, Sussex County, Newton, New Jersey 07860, 2. Extension Specialist, Rutgers NJAES Cooperative Extension, New Brunswick, New Jersey 08901, 3. Extension Specialist, Rutgers NJAES Cooperative Extension, New Brunswick, New Jersey 08901, 4. Assistant Research Professor, Rutgers University, New Brunswick, New Jersey 08901, 5 Extension Agent, Rutgers Cooperative Extension, Hunterdon County, Flemington, New Jersey 08822, 6 Extension Agent, Rutgers Cooperative Extension, Burlington County, Westampton, New Jersey 08060 Treatment TKN % Nitrate Nitrogen ppm Ammonium Nitrogen ppm Initial Final Initial Final Initial Final Pelletized Straw 1.76 2.34 a 9.45 321.94 a 6.07 3.45 Wood Shavings 1.3 1.39 b 9.5 7.67b 6.09 6.01 Effect of Composting on Nitrogen Table 1. Bedding materials effect on various forms of nitrogen. Any two means in a column with a different letter are different according to Ficher’s LSD (P=.05) Physical appearance of bedding materials after 100 days of composting. Stall waste is often spread on pasture or hay land making composting a potential solution for disposal. Manure management will continue to be an important consideration for equine operations in New Jersey 20 25 30 35 40 45 50 55 Pile Temperature (degrees C) _____ Wood Shavings Treatment > 1” >1/2” >1/4” >1/4” Initial Final Initial Final Initial Final Initial Final Pelletized Straw 25 22 26 24 25 26 24 28 Wood Shavings 26 22 27 28 25 20 24 26 Wood Shavings Pelletized Straw Table 2. Percentage of material particle size before and after composting. Any two means in a column with a different letter are different according to Ficher’s LSD (P=.05) Particle Size Distribution 0 100 200 300 400 Pelletized Straw Wood Shavings Mass (Kg) Dry Mass Initial Final Figure 2. Dry matter mass (Kg). Any column with an * is significantly different according to Fischer’s LSD (P=.05) 0 20 40 60 80 100 Pelletized Straw Wood Shavings % Organic Carbon Initial Final Figure 3. Percent organic Carbon. Any column with an * is significantly different according to Fischer’s LSD (P=.05) 0 50 100 150 Pelletized Straw Wood Shavings PPM Available P Initial Final Figure 4. Available Phosphorus (PPM). Any column with an * is significantly different according to Fischer’s LSD (P=.05) 0 20 40 60 80 100 Pelletized Straw Wood Shavings PPM Available K Initial Final Figure 5. Available Potassium (PPM). Any column with an * is significantly different according to Fischer’s LSD (P=.05) Figure 1. Temperature (°C) during 2010 composting cycle.