Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2000
Publication Date: 6/15/2000
Citation: Raper, R.L., Reeves, D.W., Burmester, C.H., Schwab, E.B. 2000. Tillage depth, tillage timing, and cover crop effects on cotton yield, soil strength, and tillage energy. Applied Engineering in Agriculture. 16(4):379-385. Interpretive Summary: Declining cotton yields have plagued farmers trying to eliminate tillage from their farms in the Tennessee Valley Region of North Alabama. Many farmers have tried to reduce tillage to meet conservation compliance programs, but have found inadequate rooting systems due to excessive soil compaction severely reduced yields. Measurements of soil strength, energy requirements, and crop yield all point to the need for cover crops and possibly shallow fall in-row tillage as management alternatives to help farmers achieve optimum yields while enhancing their soil erosion protection over traditional conventional tillage systems. Research results from these and related experiments offer farmers alternatives that will allow them to maintain or improve their yields, reduce input costs, and protect their soils.
Technical Abstract: During the early 1990's, declining cotton (Gossypium hirsutum L.) yields plagued farmers in the Tennessee Valley Region of North Alabama who tried to eliminate conventional farming systems which included moldboard and/or chisel plowing. Many farmers tried to replace conventional tillage with no-tillage to meet conservation compliance programs, but encountered severely reduced yields, possibly due to inadequate rooting systems from excessive soil compaction. A study was conducted from 1995- 1998 to develop conservation tillage systems which incorporated a rye (Secale cereale L.) cover crop and in-row tillage to maintain surface cover and disrupt root-impeding soil layers. Energy requirements for shallow tillage (18 cm) and deep tillage (33 cm) performed in the fall and spring were also assessed. Factors investigated included timing of tillage, depth of tillage and use of a cover crop. A rye cover crop was found to be the largest single factor in increasing seed cotton yields, with positive results seen in three of four years. Of somewhat lesser importance, fall tillage and shallow tillage increased seed cotton yields in years containing typical growing seasons. The conservation tillage practice of shallow, fall, in-row subsoiling in conjunction with a cover crop may offer the best alternative for farmers trying to reduce the negative effects of soil compaction, maintain adequate residue cover, and improve seed cotton yield.