Conservation Tillage Systems for Cotton Production

Abstract Cotton ( Gossypium hirsutum L.) production is intensive in many areas of the southeastern USA, and the common tillage system used is a highly erosive fall plow‐winter fallow‐spring disk. The primary purpose of this 3‐yr field study was to evaluate seeding systems for winter cover crops, effect of cover crop management on cotton production, and N fertilizer requirements for cotton following various winter cover crops. Treatments consisted of (i) winter cropping systems fall plow‐winter fallow; winter fallow; and three cover crops, rye ( Secale cereale L.), hairy vetch ( Vicia villosa Roth.), and crimson clover ( Trifolium incarnatum L.); (ii) cover crop seeding methods (broadcast interseeded prior to cotton defoliation or drill seeded after picking); (iii) spring tillage (disk or no tillage prior to cotton planting); and (iv) N rates for cotton (0, 34, 67, and 101 kg N ha −1 ). The soil was a Decatur silt loam (clayey, kaolinitic, thermic, Typic Paleudults). Interseeding resulted in adequate cover crop stands for all covers each year, but drill seeded clover winter killed 2 out of 3 yr. Total N in the legume tissue at cotton planting was higher for interseeded (120–145 kg N ha −1 ) than drill seeded (33–86 kg N ha −1 ). In 1 of the 3 yr, cotton seedling mortality was higher with no tillage than disk tillage. None of the conservation‐tillage systems resulted in higher cotton yields than the fall plow system. Planting into killed rye resulted in yields equal to the fall plow system, but more fertilizer N (approximately 34 kg N ha −1 ) was required for cotton planted into rye. When cotton followed vetch, yields were equal to the fall plow system in 2 of the 3 yr, and N fertilizer requirements were reduced approximately 34 kg ha −1 . When compared with fall plow, no tillage into clover or winter fallowed soils resulted in inferior cotton yields each year.