Poultry Litter Application Time Effect on Nutrient Availability and Corn Yield In Central Kentucky.

With the growing interest in poultry litter (PL) use as nutrient sources, whether fall versus spring application is consequential to production, is pertinent.   This study investigated impacts of fall and spring applications of two PL rates (9.0 Mg-ha^-1 and 18.0 Mg-ha^-1) and a  blend of commercial fertilizers, CF (224 kg N ha^-1) on soil nutrient and corn grain yield.  Soil nutrient increases dominated the top 15 cm.  Only Inorganic N (IN) and K were impacted by PL application time.  Increases in inorganic N were greater from spring treated CF plots and from the high PL rate; higher K observed from fall treated PL plots.  Inorganic N was greater from spring treated CF plots in July and November by averages of 28% and 26% in 2007 and 2008.  Soil K concentrations were greatest from fall treated plots in April (13%, 30% and 38%) each consecutive year.  Application time of treatments did not impact grain nutrient uptake and corn grain yield.  All treatments increased grain N uptake and yield; differences among treatments were only in 2008 for N.  The higher PL rate resulted in 12% higher grain N uptake; 7% higher yield than the lower rate but was not different from the CF treatment.   Responses were reversed for P; smallest concentrations from the CF (10%) than control compared to 21 % from the PL rates.  Results from this study seem to indicate that fall application of PL to corn potentially produces grain yield equivalent to spring application.