Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2013
Publication Date: N/A
Citation: Interpretive Summary: Winter small grain crops offer high quality forages for grazing and help to reduce soil erosion, enhance rainfall infiltration, and improve soil quality. They can also serve as cover crops prior to minimum or no-till establishment of row crops. Grazing small grain cover-crops prior to no-till establishment of a row crop is less common due to concerns of potential for soil compaction and effects on seed placement. However, little is known about the actual impacts of grazing on the following crops. The objective of this study was to determine effects of grazing a rye cover crop by beef steers within a long term (1999-2008) rye-cotton-wheat-fallow-rye rotation on growth of rye, stand establishment and yield of cotton, and on possible allelopathic effect of rye to the establishment and early growth of following crop. The results showed that 1) long-term cotton-cover crop rotation enhanced cotton growth and development comparing to monoculture cotton; 2) comparing with non-grazed plots, grazing the cover crop prior to no-till planting of cotton reduced the amount of allelopathic chemicals in soil, increased cotton plant establishment (germination rate), early season growth rate and boll setting. This study indicates that grazing cover crops have multiple benefits in improving soil quality and crop
Technical Abstract: Small grain cover crops offer opportunities for grazing but effects on following row crops are not well understood. From 1999 through 2008, stocker steers sequence grazed small grains in a 2-paddock rye-cotton-wheat-fallow- rye rotation. Treatments imposed on rye included 1) zero-grazing from 1999; 2) ungrazed in the sampling year only; 3) always grazed, and 4) long-term (since 1999) continuous cotton with no cover crop. The objective of this study was to determine effects of grazing a rye cover crop by beef steers within a long term crop rotation on the growth of rye, stand establishment and yield of following crop cotton, and on the allelopathic effect of rye to the following crop. Results showed that rye excluded from grazing for 1 year only (Trt 2) was taller (P < 0.04) and produced more forage mass than zero-grazed rye (Trt 1). Cottons that planted into grazed field have high plant density and grew faster before flowering (P < 0.05) than that of zero-grazed field. Moreover, cotton plants in continuous cotton field (Trt 4) were smaller (P < 0.01) than those grown in cover-crop rotation fields regardless of grazing. Known allelopathic chemicals were detected in both rye and soil where rye grew. It appears that grazing reduces the amount of allelopathic chemicals in the rotation field and has a positive effect on germination, early season growth and productivity of following crop cotton plants.