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.