Cover crops and nutrient retention for subsequent sweet corn production

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 wate rways and ground Hater, Cover crops planted alter sweet corn harvest could absorb residual soil N and minimize losses of fertilizer in gravitational w ater. Field experiments Here conducted on a Ste. Rosalie heavy clay (fine, mixed, frigid, Typic Humaquept) and a St. Bernard sandy clay loam (fine loa my, mired, nonacid, frigid Typic Eutrochrept). Cover crop effects on nutrie nt uptake, subsequent N release, loss of N, P, and Ii in leaching Hater, an d denitrification rates Here measured. Fertilizer N rates were 0, 75, and 1 50 kg ha(-1). Cover crops Here red clover (Trifolium pratense L.), crimson clover (Trifolium incarnatum L,), forage radish (Raphanus sativus L.), cano la (Brassica rapa L.), barley (Hordeum vulgare L), and annual ryegrass (Lol ium multiflorum L). A control treatment with no cover crop was also include d. Three replicates Here used in a split-plot arrangement of a randomized c omplete block design. Fall residual soil NO3--N levels Here higher in contr ol plots than cover crop plots. Gravitational water NO3--N was greater in c ontrol plots and ranged from 17 to 76 kg N yr(-1) N, compared with col er c rop plot values of 1 to 55 kg N yr(-1). Cover crops had no effect on denitr ification rates, or on NH4+-N, P, or li concentrations in gravitational Hat er, Forage radish, canola, and barley were effective cover crops in reducin g soil NO3--N. Cover crop effects on subsequent sweet corn were found only in grain N uptake.