Fall- and Spring-Applied Poultry Litter Effectiveness as Corn Fertilizer in the Mid-Southern United States

The effectiveness of fall-or winter-applied poultry litter, relative to spring-applied litter, as row crop fertilizer in the southern and southeastern United States has not been well researched. A 3-yr field study was conducted in northern Mississippi to determine the effectiveness of litter as corn (Zea mays L.) fertilizer and quantify loss of its potency when applied in the fall. The grain yield and biomass of corn that received fall-applied poultry litter (9 or 18 Mg ha(-1)) or 202 kg ha(-1) NH4NO3-N was compared against that of corn that received the same fertilization treatments applied in the spring including an unfertilized control. Corn fertilized with 18 Mg ha(-1) litter applied in the spring produced 24% less grain yield in the first year but up to 21% more grain yield in the last 2 yr than corn fertilized with spring-applied NH4NO3. Unlike the common assumption that 50 to 65% of the total litter N is available in the same year of application, we estimated only 31% of the total N from 18 Mg ha(-1) spring-applied litter was available to corn in the first year. Applying 18 Mg ha(-1) litter in the fall, relative to spring, reduced grain yield by 12.8% and biomass by 15.0% when averaged across the 3 yr. These results show that applying poultry litter in the fall in regions with warm fall and winter months similar to that of northern Mississippi reduces its value as a fertilizer and could potentially increase environmental risk.