Crop Sequence Effects on Response of Corn and Soil Inorganic Nitrogen to Fertilizer and Manure Nitrogen
1995
Lory, John A. | Randall, Gyles W. | Russelle, Michael P.
Fertilizer N and manure frequently are applied to corn (Zea mays L.) grown after alfalfa (Medicago sativa L.) at rates similar to those applied to continuous corn, although corn following alfalfa typically requires little additional N to attain maximum dry matter. Consequently, similar amounts of applied N may affect soil NO₃ differently in rotational than in continuous corn. There is little information evaluating crop sequence effects on residual soil NO₃ derived from fertilizer N and manure. In two 2-yr experiments at two locations in Minnesota, we evaluated the effect of crop sequence on response of corn grain dry matter, grain N, and stover N, and of soil inorganic N (NO₃-N and NH₄-N) to fertilizer N and dairy manure. Grain dry matter of first-year corn following alfalfa did not respond to applied N at Rosemount and typically was less responsive than continuous corn at Waseca. Crop sequence effects on soil NO₃ response to manure and fertilizer N were similar. Preplant fertilizer N application of 157 kg ha⁻¹ increased residual soil NO₃-N the following spring an average of 45 kg ha⁻¹ more in first-year corn following alfalfa than in continuous corn, except when excessive precipitation caused apparent high losses of applied N. Grain N content and soil NO₃ responded similarly to fertilizer N in both second-year corn following alfalfa and continuous corn. Efforts to reduce the buildup and potential loss of soil NO₃ in the corn portion of alfalfa-corn rotations should focus on reducing N application to first-year corn following alfalfa. These N applications have little agronomic value and can dramatically increase residual soil NO₃. Joint contribution of the USDA-ARS Plant Science Res. Unit, U.S. Dairy Forage Res. Ctr. (Minnesota Cluster), and Minnesota Agric. Exp. Stn. Paper no. 21902 of the scientific journal series.
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