Conservation tillage and cover crop influences on cotton production on a southeastern US coastal plain soil

Understanding cover crop and tillage system interactions within specific environments can help maximize productivity and economic returns of cotton (Gossypium hirsutum L.) produced on sandy coastal plain soils of the southeastern USA. A strip-plot design with three replications was used to evaluate the cover crops 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.) and tillage (strip and none) influences on cotton grown on a Bonifay fine sand (loamy, siliceous, subactive, thermic Grossarenic Plinthic Paleudults) near Waynesboro, GA from 1999 to 2003. Drought influenced production 3 of 4 yr. Cover crop biomass was greatest from rye, intermediate from black oat, oilseed radish, hairy vetch, and Austrian winter pea. Hairy vetch and Austrian winter pea contained more than 80 kg N ha(-1) while other cover crops averaged < 40 kg N ha-(1.) Cotton yields following black oat and rye had returns above variable costs ha(-1) $461 and $406, respectively. Strip-tillage increased yields by 192 kg ha(-1) and annual returns by $112 ha(-1) over no-tillage, most likely due to improved available water. Combining strip-tillage with black oat was the best combination for maximizing profit. 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.