Conservation Tillage Systems for Cotton in the Tennessee Valley

Abstract

Yield reductions from no-tillage cotton (Gossypium hirsutum L.) jeopardized adoption of conservation systems in the Tennessee Valley region of north Alabama in the early 1990s. We conducted a study from 1995 to 1999 on a Decatur silt loam (fine, kaolinitic, thermic Rhodic Paleudults) to develop a practical conservation tillage system with competitive yields for the region. Treatments included a factorial combination of fall ridging (ridged and nonridged) and fall non-inversion deep tillage (none, in-row subsoiling, paratilling), along with spring strip tillage and conventional tillage (fall chisel-spring disk). All treatments, except conventional tillage, were established with a rye (Secale cereale L.) cover crop. Tillage systems were evaluated for soil temperature, penetration resistance, a soil compaction index, soil water, plant population, and seed cotton yield. Paratilling reduced soil compaction index 29 and 31% compared with conventional tillage and no-tillage, respectively. Subsoiling reduced the compaction index 12 and 15% compared with conventional tillage and no-tillage, respectively. Soil water content was decreased with the fall paratilled and subsoiled conservation tillage systems, compared with conventional tillage and no-tillage, suggesting increased rooting. Fall non-inversion deep tillage, either paratilling or in-row subsoiling with a narrow-shanked subsoiler, resulted in the highest seed cotton yields; 16% greater than conventional tillage (2660 kg ha−1), and 10% greater than strict no-tillage (2810 kg ha−1) across a 4-yr duration. In this region, non-inversion deep tillage under the row in fall, coupled with a rye cover crop to produce adequate residue for moisture conservation and erosion control, is a highly competitive and practical conservation tillage system.