Influence of Winter Cover Crop and Residue Management on Soil Nitrogen Availability and Corn

Abstract

Removing cover crop top growth in the spring for forage or to prevent incorporation problems is one management option. The effects of this residue management on soil quality and productivity need to be determined. This study, conducted from 1994 to 1998 at Puyallup, WA, determined effects of various winter cover crops and residue management on soil N availability, soil C and N, and corn (Zea mays L.) yield. Included in the study were monocultures of rye (Secale cereale L.), ryegrass (Lolium multiflorum Lam), and vetch (Vicia villosa Roth subsp. villosa) and biculture of vetch and rye or ryegrass. Each year, the cover crops were seeded in the fall and incorporated into, or removed from, the soil in the spring. Average top‐growth biomass was higher for the bicultures than for the monocultures. Total N accumulation was generally greatest under vetch, followed by the bicultures, and lowest for the monocultured rye or ryegrass. Whereas removing top growth of monocultured vetch or bicultures depressed presidedress soil NO3–N (Ni), the effect was generally not found for monocultured rye or ryegrass. Corn yields were affected by amounts of Ni and N fertilizer applied (r2 > 0.789), irrespective of cover crop species and residue management. Removing top growth of the cover crops limited residue C input and reduced soil organic C and N after 5 yr. Soil organic C and N accumulation, as well as increasing soil C sequestration to reduce CO2 release into atmosphere, should be considered when deciding which residue management option to choose.