Characterization and utilization of nitrogen contained in sweet corn silage waste

Sweet corn (Zea mays L. var. rugosa Bonaf.) silage waste (SCSW), a byproduc t of the vegetable processing industry, accounts for 61 to 73% of the initi al harvest yield. Concern relating to land application of SCSW has focused on the potential environmental impact of large quantities of mineralized N from the waste. This study was conducted to quantify the rate and amount of N mineralization from varying rates of SCSW applied to a fine-textured gla cial till soil and to determine if nutrient contributions from SCSW can be integrated into a nutrient management system for subsequent crop production while enhancing environmental stewardship. Sweet corn silage waste was lan d-applied to main plots at rates of 0, 112, 224, 336, and 448 t ha(-1) (fre sh,vt,) to a harvested sweet corn field and moldboard-plowed in early fall. Urea [(NH2)(2)CO] was preplant broadcast-applied and incorporated to subpl ots at rates of 0, 67, and 134 kg N ha(-1) in 1993; and 0, 83, and 166 kg N ha(-1) in 1994 and 1995, Mineralization of N in the SCSW was assessed by N O3-N analysis of in-season and postharvest soil samples and by yield and N uptake of field corn. Spring temperature and precipitation greatly influenc ed mineralization of SCSW. In the wet, cold year, in-season NO3-N concentra tions were lower and postharvest NO3-N was not affected by SCSW rate, Grain yield and N uptake were increased with increasing SCSW rate. In the warmer and drier Scars, in-season and postharvest NO3-N concentrations were much greater and were significantly increased by increasing SCSW rates. Corn gra in yield and N uptake were optimized by a combination of SCSW and fertilize r N when SCSW rates were < 224 t ha(-1). At rates > 224 t hn-L, mineralized N from the SCSW was sufficient to maximize yields. Nitrogen availability i n the first year after SCSW application averaged about 16 to 18% of the tot al SCSW-N applied. Averaged across tile 3 yr, soil test P was increased 2.6 mg kg(-1) with each 112 t ha(-1) SCSW rate, whereas soil test K was increa sed 14.2 mg kg(-1) by each 112 t ha(-1) SCSW rate, Land application of up t o 224 t ha(-1) SCSW was feasible, provided it was given tile appropriate N credit before supplementing with N fertilizer.