Cover Crops and Nutrient Retention for Subsequent Sweet Corn Production

Abstract

The use of high rates of N fertilizer in intensive sweet corn (Zea mays L.) production may result in leaching losses and contamination of adjacent waterways and ground water. Cover crops planted after sweet corn harvest could absorb residual soil N and minimize losses of fertilizer in gravitational water. Field experiments were conducted on a Ste. Rosalie heavy clay (fine, mixed, frigid, Typic Humaquept) and a St. Bernard sandy clay loam (fine loamy, mixed, nonacid, frigid Typic Eutrochrept). Cover crop effects on nutrient uptake, subsequent N release, loss of N, P, and K in leaching water, and denitrification rates were measured. Fertilizer N rates were 0, 75, and 150 kg ha−1 Cover crops were red clover (Trifolium pratense L.), crimson clover (Trifolium incarnatum L.), forage radish (Raphanus sativus L.), canola (Brassica rapa L.), barley (Hordeum vulgare L.), and annual ryegrass (Lolium multiflorum L.). A control treatment with no cover crop was also included. Three replicates were used in a split‐plot arrangement of a randomized complete block design. Fall residual soil NO−3–N levels were higher in control plots than cover crop plots. Gravitational water NO−3–N was greater in control plots and ranged from 17 to 76 kg N yr−1 N, compared with cover crop plot values of 1 to 55 kg N yr−1. Cover crops had no effect on denitrification rates, or on NH+4–N, P, or K concentrations in gravitational water. Forage radish, canola, and barley were effective cover crops in reducing soil NO−3–N. Cover crop effects on subsequent sweet corn were found only in grain N uptake.