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.