WATER-CONTENT EFFECT ON DENITRIFICATION AND AMMONIA VOLATILIZATION IN POULTRY 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 land application, losses of inorganic N may occur through denitrification and NH3 Volatilization. This work was conducted to evaluate the effect of litter water content on denitrification and NH3 volatilization during storage. Litter samples from two broiler houses in northern Georgia were incubated (25-degrees-C) at four water contents for 13 d. Water contents used Were 230 g H2O kg-1 in Litter A, 160 g H2O kg-1 in Litter B, and 800, 1200, and 2400 g H2O kg-1 in both litters. These water contents were equivalent to 8, 26, 40, and 79% water-holding capacity (WHC) in Litter A and to 7, 33, 49, and 99%) WHC in Litter B, respectively. 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 evolved from samples incubated without C2H2. Denitrification was significant at the highest water content and increased with the addition of NO3-. Measured denitrification losses varied between 41 and 79% of the initial NO3-, although final NO3- levels suggested that denitrification losses were larger (92-100%) and that part of the N2O produced remained 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 under dry conditions to reduce N losses.