WATER-CONTENT EFFECT ON DENITRIFICATION AND AMMONIA VOLATILIZATION INPOULTRY LITTER

Poultry litter is a mixture of excreta, bedding material, waste feed, and some soil that is removed from poultry houses and applied to soil as fertilizer. Because litter is commonly stockpiled outdoors before l and application, losses of inorganic N may occur through denitrificati on and NH3 Volatilization. This work was conducted to evaluate the eff ect of litter water content on denitrification and NH3 volatilization during storage. Litter samples from two broiler houses in northern Geo rgia were incubated (25-degrees-C) at four water contents for 13 d. Wa ter contents used Were 230 g H2O kg-1 in Litter A, 160 g H2O kg-1 in L itter B, and 800, 1200, and 2400 g H2O kg-1 in both litters. These wat er contents were equivalent to 8, 26, 40, and 79% water-holding capaci ty (WHC) in Litter A and to 7, 33, 49, and 99%) WHC in Litter B, respe ctively. Denitrification was evaluated by measuring N2O emission from samples incubated with 10 kPa C2H2, with and without additional NO3- ( 15 mg N g-1). Ammonia volatilization was evaluated by measuring NH3 ev olved from samples incubated without C2H2. Denitrification was signifi cant at the highest water content and increased with the addition of N O3-. Measured denitrification losses varied between 41 and 79% of the initial NO3-, although final NO3- levels suggested that denitrificatio n losses were larger (92-100%) and that part of the N2O produced remai ned entrapped in the litter. Ammonia volatilization losses ranged from 32 to 139% of the initial NH4+ and were increased by increasing water content. These results suggest that poultry litter should be stored u nder dry conditions to reduce N losses.