Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/28/2006
Publication Date: 9/5/2006
Citation: Schomberg, H.H., Mcdaniel, R.G., Mallard, E., Endale, D.M., Fisher, D.S., Cabrera, M.L. 2006. Conservation tillage and cover crop influences on cotton production on southeastern USA coastal plain soils. Agronomy Journal. 98:1247-1256. Interpretive Summary: Cover crops are important for the success of conservation cropping systems. Which cover crop to grow is a decision producers face each year. New and alternative cover crops may benefit cropping systems through reductions of disease, weeds, and pests, and improved water relations and nutrient use. Scientists from the J. Phil Campbell, Sr, Natural Resource Conservation Center, in Watkinsville, GA along with cooperators from the University of Georgia and Monsanto Inc. compared seven cover crops for use in conservation cropping systems for cotton on a Coastal Plain soil. Their objective was to determine if the cover crops would perform better than rye, the standard cover crop for cotton. Two of the cover crops, black oat and oilseed radish, are new to the southeast but are major cover crops in southern Brazil and Paraguay. Researchers also compared Austrian winter pea, balansa clover, crimson clover, and hairy vetch, to rye in systems using strip-tillage or no-tillage. Drought influenced cotton yields the first three years. Biomass production, which is important for reducing soil erosion and evaporative water loss, was greatest from rye, intermediate from black oat, oilseed radish, hairy vetch and Austrian winter pea, and less from crimson clover and balansa clover. The legumes hairy vetch and Austrian winter pea fixed more nitrogen than the other legume cover crops. These two legumes could provide more than half the nitrogen needed to grow a cotton crop. Cotton growth following the cover crops was similar most years but positive benefits from black oat were detected. Cotton yields and estimated annual returns were greatest following black oat and rye and were greater in the strip-tillage system than in the no-till system. The improvement was most likely due to the greater biomass produced by rye and black oat and disruption of a compacted soil layer by strip-tillage. Adoption of black oats with strip-tillage could increase cotton profit by $20 to $30 per acre compared to systems using rye. A majority of the 2.9 million acres of cotton produced in the Southeast is located on the Costal Plain where adoption of conservation systems in cotton is 50%. Cotton producers in the region can benfit from adopting this system and the information is important for producers, extension agents, NRCS, and agricultural consultants.
Technical Abstract: A majority of the 2.9 million acres of cotton (Gossypium hirsutum L.) produced in the Southeastern USA is located on Coastal Plain sandy soils that can benefit from conservation cropping systems. An understanding of cover crop and tillage system interactions is needed within specific environments to maximize productivity and economic returns. Austrian winter pea (Pisum sativum L. ssp. arvense (L.)), balansa clover (Trifolium michelianum Savi), crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa Roth subsp. villosa), oil seed radish (Raphanus sativus L.), black oat (Avena strigosa Schreb), and rye (Secale cereale L) were evaluated as winter cover crops for influences on cotton production using strip-tillage and no-tillage on a Bonifay fine sand (Grossarenic Plinthic Paleudult) near Waynesboro, Georgia. Drought influenced cover crop and cotton production three of four years of the study. Biomass production was greatest from rye, intermediate from black oat, oilseed radish, hairy vetch and Austrian winter pea, and less from crimson clover and balansa clover. Hairy vetch and Austrian winter pea contained more than 80 kg N ha-1 while other cover crops averaged less than 40 kg N ha-1. Early season cotton stand counts, plant height, biomass, and N content were similar among cover crops most years but some positive impacts from black oat were detected. Average cotton yields were greatest following black oat and rye and less following balansa clover, crimson clover, and hairy vetch. Annual returns above variable costs ha-1 were greatest for black oat ($461) and rye ($406). Strip-tillage increased yields by 192 kg ha-1 and annual returns by $112 ha-1 over no-tillage, most likely due to improved rooting depth and available water. Combining strip-tillage with black oat was the best treatment combination tested for maximizing profit in conservation cotton production systems on sandy Coastal Plain soils. Using black oat with strip-tillage could increase cotton profit by $50 to $75 ha-1 compared to systems using rye on the 1.45 million ha of cotton where conservation systems have been adopted.