Influence of Poultry Litter On Inorganic Soil N Concentrations and Rice Yields.

Rice (Oryza sativa L.), is grown on approximately five hundred thousand hectares in Arkansas each year, making Arkansas the leading rice producing state in the United States. Poultry litter is one of the most nutrient rich manures and is applied to a large amount of row crop acres each year in Arkansas. Poultry litter (PL) is typically applied to satisfy phosphorus and potassium recommendations, however a study conducted by Golden et al. (2006) indicated that about 25% of the TN applied as PL was recovered by the rice crop. Most of the N in poultry litter is in the organic form (approximately 75%), with the remaining 25% of the total-N found in PL as inorganic-N, mainly in the form of NH4+-N. The objective of this research is to quantify changes in NH4+-N and NO3--N concentrations occurring in the soil following the application of pelletized PL one month prior and at rice planting using a 2 M KCl extraction. Two field experiments in 2011 were established at two locations on silt loams to evaluate crop and soil responsiveness to pelletized PL as a fertilizer. Poultry litter applications resulted in significant increases in rice yield and were influenced by the two-way interaction of location and PL rate. Application time influenced rice yields as PL applied at planting resulted in higher yields than the equivalent rate applied one month prior to planting. Within the one month prior application the peak concentrations of inorganic-N were identified 2-wk after planting. However, the peak concentration of NO3--N occurred 4-wk after planting for the at-planting application. The results of this experiment indicate the need for further research concerning PL applications impact on Nitrogen-Soil Test for Rice soil test values and the potential for high levels of PL to alter its recommendations on silt loam soils.