Recovery of Nitrogen in Fresh and Pelletized Poultry Litter by Rice

Abstract

The N‐fertilizer value of preplant incorporated poultry litter for rice (Oryza sativa L.) grown using the direct‐seeded, delayed‐flood (DF) production system is unknown. The research objective was to compare preplant incorporated fresh (FPL) and pelleted (PPL) poultry litter with urea applied preflood to determine the urea‐nitrogen (N) equivalence of poultry litter for rice. Fresh and pelleted litter were preplant incorporated at total‐N rates ranging from 34 to 270 kg N ha−1 and compared with urea applied preflood at rates ranging from 34 to 168 kg N ha−1 at five site‐years on silt loam soils. Net‐N uptakes and grain yields between FPL and PPL were similar, but significantly lower when compared with urea applied preflood, regardless of site‐year. By heading, when averaged across all N rates and site‐years, rice recovery of the urea‐N applied preflood averaged 76%. In contrast, the apparent recovery of N applied as FPL or PPL averaged only 14%. Net‐grain yields for rice fertilized with urea increased nonlinearly as N rate increased with near maximal yields produced with ≥101 kg urea‐N ha−1 Grain yields for FPL and PPL increased linearly and approached the near maximal yields produced with urea‐N only when 270 kg total‐N ha−1 was applied. Based on net grain yield, multiplying the total‐N content in FPL and PPL by 0.25 reasonably estimates its equivalence to urea applied preflood. Recommended preflood urea‐N rates should be decreased by 0.25 times the total N applied as poultry litter.