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 NH 3 volatilization. This work was conducted to evaluate the effect of litter water content on denitrification and NH 3 volatilization during storage. Litter samples from two broiler houses in northern Georgia were incubated (25°C) at four water contents for 13 d. Water contents used were 230 g H 2 O kg −1 in Litter A, 160 g H 2 O kg −1 in Litter B, and 800, 1200, and 2400 g H 2 O 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 N 2 O emission from samples incubated with 10 kPa C 2 H 2 , with and without additional NO − 3 (15 mg Ng −1 ). Ammonia volatilization was evaluated by measuring NH 3 evolved from samples incubated without C 2 H 2 . Denitrification was significant at the highest water content and increased with the addition of NO − 3 . Measured denitrification losses varied between 41 and 79% of the initial NO − 3 , although final NO − 3 levels suggested that denitrification losses were larger (92–100%) and that part of the N 2 O produced remained entrapped in the litter. Ammonia volatilization losses ranged from 32 to 139% of the initial NH + 4 and were increased by increasing water content. These results suggest that poultry litter should be stored under dry conditions to reduce N losses.