Nitrogen mineralization rates of soils amended with nontraditional organic wastes

Nitrogen mineralization rate (NMR) studies provide a means to determine plant-available N resulting from organic waste applications. Nontraditional organic wastes (food processing and yard wastes) were applied at two different rates (112 kg N ha super(21) and 224 kg N ha super(21)) to soils from two different soil series, Adelphia sandy clay loam (Aquic Hapludults) and Sassafras sandy loam (Typic Hapludults) in a 25-week laboratory incubation study. Supplemental ammonium sulfate was added to the soils amended with wastes with high C/N ratios. Nitrogen mineralization rates were reported as the percent organic N mineralized from organic waste. The NMR ranges for the vegetable food processing wastes were 13.9 to 55.1% (Adelphia soil) and 17.0 to 66.8% (Sassafras soil); for the other food processing wastes: 220.8 to 39.9% (Adelphia soil) and 220.5 to 47.7% (Sassafras soil); and for the yard wastes: 226.7 to 29.8% (Adelphia soil) and 222.6 to 65.6% (Sassafras soil). The application rates of the wastes and the two soil types affected the NMRs of several of the organic wastes studied significantly (P < 0.05). The effect of waste characteristics and soil type on NMRs needs to be accounted for if organic wastes are to be used as a N source. One option is to apply organic wastes at rates below agronomic recommendation rates, based on NMRs, and to supply additional inorganic N as needed.