Submitted to: Tillage Conference for Sustainable Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 7/9/2001
Publication Date: 7/9/2001
Citation: Schwab, E.B., Reeves, D.W., Burmester, C.H., Raper, R.L. 2001. Reducing soil compaction and improving cotton yield with conservation in the tennessee valley. Proceedings of the 24th Annual Southern Conservation Tillage for Sustainable Agriculture, Oklahoma City, OK. pp. 42-49. July 9-11.
Interpretive Summary: Soil erosion from continuous cotton cropping and governmental regulations forced many cotton producers in the Tennessee River Valley of northern Alabama to try no-tillage in the early 1990's, but yield reductions prevented widespread adoption of this beneficial system. We implemented research to develop a practical conservation tillage system for the region that results in competitive cotton yields and improvements in soil quality. Six conservation tillage systems that integrated a rye cover crop with fall ridging and fall non-inversion deep tillage (paratilling or in-row subsoiling) were compared to a no-tillage system and a conventional tillage system for five years. Paratilling or subsoiling in fall, coupled with the rye cover crop, reduced soil compaction from 20 to 23% and increased yield 10 to 16% compared to no-tillage and conventional tillage. This information has been rapidly transferred to growers, consultants, extension agents, and NRCS staff, resulting in adoption rates of conservation tillage exceeding 70 to 80% in the largest cotton producing counties in the region (over 120,000 acres of conservation tillage cotton).
Technical Abstract: Yield reductions with strict no-tillage in the Tennessee Valley of north Alabama jeopardized adoption of conservation systems in this region. Consequently, we implemented a four year study on a Decatur silt loam in 1994 to develop a practical conservation tillage system that results in competitive cotton (Gossypium hirsutum L.) yields. Treatments included a factorial combination of fall ridging (ridged and non-ridged) and fall deep tillage (none, in-row subsoiling, paratilling); along with spring strip tillage and conventional tillage. With the exception of the conventional tillage, all treatments were established with a rye (Secale cereale L.) cover crop. Tillage systems were evaluated for plant population, soil compaction, soil water content, and seed cotton yield. Cotton populations with conservation tillage were similar to the conventional tillage system and adequate stands were obtained in all treatments far all years. Soil compaction index (function of compaction intensity and volume of affected soil) was reduced by fall paratilling (29%-31%) and in-row subsoiling (12-15%), compared to conventional tillage and strict no- tillage, respectively. Both fall subsoiling and paratilling reduced soil water content (increased soil water removal by cotton roots) under the row compared to strict no-tillage. Fall deep tillage, either paratilling or in-row subsoiling, resulted in the highest seed cotton yields (2,760 lb ac-1); 16% greater than conventional tillage, and 10% greater than strict no-tillage over a 4 y duration. Deep tillage (subsoiling or paratilling) and the use of cover crops is the most competitive system for farmers trying to convert to conservation tillage in this region.