Simulating the Fate of Fall- and Spring-Applied Poultry Litter Nitrogen in Corn Production

Knowledge of the fate of manure N is important to effectively manage it and minimize its environmental impact. The system model RZWQM2 was calibrated and evaluated using 3 yr of data to simulate the mineralization and fate of fall-and spring-applied poultry litter N. Litter (18 Mg ha(-1)) and, for comparison, NH4NO3 (202 kg N ha(-1)) were applied in fall and spring from 2006 to 2008 in a corn (Zea mays L.) field near Starkville, MS. The model estimated that 57% (279 kg ha(-1)) of the total litter N applied in the fall and 51% (249 kg ha(-1)) of that applied in the spring had mineralized by the end of the first year in November. The loss of mineralized litter N by the end of the first year was 24 vs. 9% of the total applied for the fall vs. spring applications, respectively. At the end of the experiment in November 2008, 88% of the total 1507 kg ha(-1) litter N applied in the previous three falls and 72% of that applied in the previous three springs was mineralized. The loss of mineralized litter N averaged across the 3 yr was 162 kg ha(-1) (37% of the total mineralized) if applied in the fall and only 55 kg ha(-1) (15% of the total mineralized) if applied in the spring. The primary avenue of litter N loss was leaching if applied in the fall and denitrification if applied in the spring. These results clearly demonstrate that spring is the best time to apply litter in the southeastern United States.