Robert B. Norris, Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA, Wade E. Thomason, School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, Gregory K. Evanylo, 185 Ag Quad Lane, Virginia Tech, Blacksburg, VA and Mark S. Reiter, Eastern Shore AREC, Virginia Tech, Painter, VA
Environmental and economic goals have encouraged the use of soil nitrogen (N) tests to improve fertilizer N management in corn (Zea mays L.). However, many producers still rely on expected yields for fertilizer N management instead of in-season soil N tests. Recent attention has been given to the Solvita® CO2-Burst test as a tool to predict the soils inherent net mineralizable N potential. Our objective is to evaluate the efficacy of this, and other soil-based tests in a typical crop rotation in the mid-Atlantic coastal plain that includes winter cover crops (WCC). Winter cover crop effect on presidedress nitrate test (PSNT) soil N test was highly significant (P<0.001) for V5 sampling period. Winter CC affected grain yield at one site where high cover crop biomass levels were observed. Cover crop treatment did not result in differences in preplant soil test N (any method). However at V5, differences in soil test N levels due to cover crop were observed at total inorganic N at 0-15 cm and nitrate at 0-15 and 0-30 cm. Winter cover crop did not affect the values for the preplant or V5 Solvita® CO2-Burst test or 28 day aeriobic incubation test. The Solvita® CO2-Burst test digital number and 28-d net N mineralization were not strongly correlated at either preplant or V5.