Effects of broiler litter on soybean production and soil nitrogen and phosphorus concentrations

Although most of the N required by soybean [Glycine max (L.) Merr.] is provided through the process of symbiotic N-2 fixation, supplemental N using broiler litter may boost soybean grain yields. The effects of broiler litter and commercial fertilizer applications on soybean yield, N and P uptake, and residual soil N and P were evaluated on a Leeper silty clay loam (fine, smectitic, nonacid, thermic Vertic Epiaquepts) at the Mississippi Agriculture and Forestry Experiment Station in Starkville, MS. Treatments were broiler litter application at the rates of 0, 40, 80, 160 kg plant available N (PAN) ha(-1) and commercial fertilizer at equivalent to broiler litter PAN and P rates. Soybean grain yield and N and P uptake were quadratically increased with increasing broiler litter and commercial fertilizer application rates. Soybean grain yield and N uptake from broiler litter applications were significantly greater than those from commercial fertilizer. Soybean grain yield was not correlated to soybean P uptake but linearly increased with increasing N uptake. Application of broiler litter at rates > 80 kg PAN ha(-1) were not effectively used by soybean as evidenced by declining apparent recovery values, increasing residual soil NO3-N concentrations, and increasing P accumulation at the top 15 cm of the soil profile. For every unit of N uptake, broiler litter treatment produced 3.4% more grain yield than commercial fertilizer. The results of this study indicate that application of broiler litter to soybean may be beneficial.