- Larry Bundy
Results from the first 2 years of this study to determine the appropriate application rates for sweet corn processing wastes indicate that land application for management of waste materials is a feasible approach. Agronomic responses of field corn to applications of up to 200 tons/acre of sweet corn residue were positive. Plant emergence, plant height, dry matter yields, and grain yields were increased by increasing rates of residue application. Yield responses to residue rate occurred even where there was no response to fertilizer N, suggesting that the residue additions provide beneficial effects other than contributing N. High soil N contributions at the experimental site prevented yield response to added N.
Soil inorganic N measurements throughout the growing season show that sweet corn residues decompose with a relatively rapid release of available N. Based on these results, residue applications in the 50 to 100 tons/acre range probably would not exceed corn N requirements at responsive sites and should not leave excessive amounts of residual nitrate in the soil at the end of the growing season. Data from the residual study show that N mineralization is not complete after the first year of application, but the amount of available N supplied in the second year will not provide the entire corn N need. The residual effects of residue treatments must be considered to avoid excess N applications in the second year after residues are land-applied.
Soil water data indicate that residue treatments in excess of 100 tons/acre can increase soil water nitrate-N concentrations relative to typical corn N fertilizer rates, but by the end of the second growing season soil water nitrate-N concentrations were equal in all treatments including the control (no residue).