Residual Effects of Pelletized Broiler Litter Application to Cotton on Soybean Yield.

Broiler (Gallus gallus domesticus) litter may have long-lasting plant growth benefits after application is terminated. A study was conducted to determine the residual effects of pelletized litter applied to cotton (Gossypium hirsutum L.) on yield and nutrient utilization of soybean (Glycine max (L.) Merr.). Experimental design was a randomized complete block with three treatments replicated four times. Treatments included pelletized broiler litter subsurface banded to cotton at the rate of 6.7 Mg ha^-1, urea-ammonium nitrate (UAN solution) injected at the rate of 134 kg N ha^-1 and unfertilized control. Soybean was planted on residual broiler litter and inorganic fertilizer in 2011, 2012 and 2013. No litter or inorganic fertilizer was applied to soybean. Soybean height was determined at 28, 42, 56, 71, 86, 102 and 115 days after planting. Total aboveground biomass, leaf area index (LAI) and tissue nutrient concentrations were determined at growth stage R5. Soybean yield and plant nutrient concentrations were higher in pelletized broiler litter than fertilizer N. Soybean plants in plots received pelletized broiler litter were significantly (P<0.05) taller and had greater leaf-area than the control and plots received inorganic fertilizer. Total aboveground biomass at R5 did not differ between plots received pelletized litter and plots had fertilizer N treatment; however soybean grain yield was greatest for residual pelletized litter treatment. Soybean grain and grain N, P and K uptake were significantly greater in plots received pelletized litter than commercial fertilizer and in the control plots one year after application. Residual effects of pelletized broiler litter application increased crop production for one year and influenced soil fertility beyond the first year of application for several years.