Rice Yield and Nitrogen Recovery from Nitrogen-Fortified Poultry Litter Granular Fertilizers.

Arkansas producers raise over 1.2 billion broilers per year resulting in 1.7 million Mg of poultry litter (PL) waste excreta that must be disposed of in an environmentally friendly manner. Poultry litter granulation gives the opportunity to transform a highly variable low analysis fertilizer product into a uniform material than can be fortified to increase nutritional value. We initiated a rice (Oryza sativa) field study to test N fertilizer recovery efficiency (FRE) and agronomic efficiency for flood irrigated crops. We tested fresh PL, granulated PL fortified with urea (PLU), PLU fortified with dicyandiamide (DCD) (PLUDCD), and preflood applied urea at  67, 112, 157, and 202 kg N ha^-1 in a randomized complete block design in a 4 (N source) × 4 (N rate) factorial arrangement. A 0-N control was also included. Poultry litter treatments were preplant incorporated and compared to conventional fertility guidelines of urea applications made immediately before the permanent flood was established. Soil samples were collected at early heading to test for inorganic N, total N and total C. Rice aboveground biomass was quantified at early heading and used to calculate total N fertilizer uptake and grain yield was determined at maturity. On average, rice plants assimilated 16, 23, 53, and 89% of applied total N for PL, PLU, PLUDCD, and preflood urea and produced 14, 17, 29, and 47 kg rice kg N^-1, respectively. Fresh PL, PLU and PLUDCD had a 29, 37, and 62% N agronomic efficiency calculated on a preflood urea N application basis (100%) when applied preplant incorporated to flood irrigated rice systems.