Nitrogen and Phosphorus Use Efficiency From Litter Applied to Bermudagrass.

More than 80% of broiler (chicken, Gallus gallus domesticus) litter produced annually is applied as a plant nutrient source, particularly N and P, to pastures. However, N losses during the process of litter N mineralization limit availability of N to crops. This study determined broiler litter N and P availability and apparent use efficiency (ANUE, APUE) to bermudagrass [Cynodon dactylon.] during the first year after litter application. Treatments consisted of three litter rates (3.3, 6.6, and 13.2 Mg ha^-1), a commercial N fertilizer rate that provided 358 kg N ha^-1 as ammonium nitrate (NH₄NO₃), and an untreated control. Results showed bermudagrass dry matter (DM) yield increased significantly with increase in litter rate. Commercial N fertilizer produced significantly greater DM yield than 3.3 and 6.6 Mg ha^-1 of litter, but produced less DM yield than 13.2 Mg ha^-1 of litter. The overall average of ANUE from litter was 39% compared to the 59% from fertilizer. The mean litter N availability to bermudagrass during the first year after litter application was 48.5, 112.5, and 222 kg ha^-1 corresponding to the 3.3, 6.6, and 13.2 Mg ha^-1 litter rates, respectively. The overall mean of litter N mineralization, which was surface broadcast to bermudagrass plots during the first year, was 59.5% of the total litter N applied. The APUE, averaged across the rate and locations, was 13.6%, which was quite smaller than ANUE of 39%. This finding of small APUE also validates the potential for P accumulation in soil after longterm animal manure application.