EFFECTS OF DIFFERENT RESIDUE MANAGEMENT METHODS ON COTTON ESTABLISHMENT AND YIELD IN A NO-TILL SYSTEM

A field experiment was conducted in 2007, 2008, and 2009 in central Alabama to evaluate the effects of cover crop mechanical termination, strip tillage width, and row cleaners attached either to the tillage implement or planting units, on cotton population and yield. Treatments included roller (present or absent), in-row subsoiler (wide and narrow strips), and row-cleaners attached either to subsoiler, planter, or both. Rye was terminated with glyphosate (both rolled and non-rolled rye) in mid-April, and tillage treatments were applied; cotton was planted three weeks after tillage. In 2007, generally higher cotton stands were associated with rolled rye residue (137,134 plants/ha) vs. non-rolled rye (115,641 plants/ha). On average, significantly higher cotton seed yield was found for rolled rye (4,540 kg/ha compared to non-rolled rye (4,332 kg/ha). Examining specific treatments, the highest cotton seed yield (4,933 kg/ha) was associated with rolled rye under narrow strip tillage with row cleaners attached to both subsoiler and planter The lowest cotton yield (3,913 kg/ha) was associated with non-rolled residue, under narrow strip tillage with row cleaners present on both subsoiler and planter. In 2008, no difference was found in cotton stand for rolled (108,375 plants/ha) and non-rolled rye (107,719 plants/ha). Cotton seed yield was higher in 2008 than in 2007 due to a severe drought in Alabama during 2007. In 2008, slightly higher cotton yield was reported for non-rolled rye (5,658 kg/ha) vs. rolled rye (5,419 kg/ha). The non-rolled rye, narrow strip subsoiling, and row cleaners on subsoiler generated the highest cotton yield (5,812 kg/ha) compared with the lowest (5,171 kg/ha) by rolled rye, narrow strip, and row cleaners on the planter In 2009, cotton stand for rolled rye was higher (115,036 plants/ha) compared to non-rolled rye residue (65,894 plants/ha). In 2009, the cotton yield was substantially reduced by flooding of the experimental area. Because of the excess water; the cotton yield was lower (2,672 kg/ha) compared to 2007 and 2008 growing seasons. Soil strength measurements taken in fall 2009 showed significantly lower cone index values with rolled vs. non-rolled rye from 0 to 15-cm depth, with trends reversed after 20 cm. Cone index values at all depths, however, were below the 2-MPa threshold that indicates restrictive conditions for root growth. In all three growing seasons, the width of the tillage strip and the location of row cleaners (planter/subsoiler) did not affect cotton stand and seed cotton yield