COVER CROP MANAGEMENT AND WEED SUPPRESSION IN NO-TILLAGE SWEET CORN PRODUCTION

Authors: Carrera, Lidia; Abdul Baki, Aref; Teasdale, John

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2003
Publication Date: 7/10/2004
Citation: Carrera, L.M., Abdul Baki, A.A., Teasdale, J.R. 2004. Cover crop management and weed suppression in no-tillage sweet corn production. Hortscience. 39(6): 1262-1266.

Interpretive Summary: Field experiments were conducted at the Beltsville Agricultural Research Center, MD., to improve sustainability by developing a sweet corn production system that would reduce chemical inputs, increase yield and suppress weeds. This system eliminated tillage to reduce production cost ans soil erosion. It utilized the legume cover crops hairy vetch and rye-hairy vetch mixture to fix nitrogen, recycle other nutrients, improve soil tilth, and suppress weeds. The cover crops were planted in the fall, killed either mechanically or chemically in the following spring at sweet corn seeding time, and residues were left on soil surface to reduce water loss from the soil, suppress weed growth, and release nutrients to the corn crop. Sweet corn yields in this no-tillage cover crop system are 43 % higher in hairy vetch and 30 % higher in rye-hairy vetch mixture than in the conventional bare soil even when nitrogen fertilizer input was reduced by 50 %. The beneficiaries of this research are growers, consumers, extension specialists, scientists, and environmentalists.

Technical Abstract: Cover crops combined with conservation tillage practices can minimize chemical inputs and improve soil quality, soil water holding capacity, weed suppression and crop yields. No-tillage production of sweet corn (Zea mays var. rugosa L.) was studied for two years at the Beltsville Agricultural Research Center, MD, to determine cover crop management practices that maximize yield and suppress weeds. Cover crop treatments were hairy vetch (Vicia villosa Roth), rye (Secate cereale L.) -hairy vetch mixture, and bare soil (no cover crop) . There were three cover crop killing methods (mowing, rolling or contact herbicide paraquat). All plots were treated with or without residual herbicide (atrazine plus metolachlor) after planting. There was a 23 % reduction in sweet corn plant population in the rye-hairy vetch mixture compared to bare soil. Averaged over both years, sweet corn yield in hairy vetch treatments was 43 % greater than in bare soil, whereas yield in the rye-hairy vetch mixture was 30% greater than in bare soil. Mechanical and chemical killing methods for hairy vetch and rye-hairy vetch did not significantly affect yields. Sweet corn yields were not different for hairy vetch or rye-hairy vetch treatments with or without residual herbicide. However, yield in bare soil without residual herbicide was reduced by 63 % compared to bare soil with residual herbicide. When no residual herbicide was applied, weed biomass was reduced in cover crops compared to the bare soil. Regression analysis showed greater yield loss per unit of weed biomass for bare soil than for the vetch or rye-hairy vetch mixture. This analysis suggests that cover crops increased sweet corn yield in the absence of residual herbicide not only by reducing weed biomass, but also by increasing the competitiveness of corn to weeds at any given biomass.