EFFECTS OF A CUSTOM COVER CROP RESIDUE MANAGER IN A NO-TILL COTTON SYSTEM

摘要

Cover crops are an important part of no-till conservation agriculture, and these crops must produce optimum biomass amounts to effectively protect the soil surface from erosion and runoff, conserve soil water, and provide a physical barrier against weeds. Because of the large amount of residue produced by cover crops, the residue must be managed appropriately to minimize planting problems for producers. A study was conducted at the E.V. Smith Research and Extension Center (EVS) in central Alabama to determine the effects of commercially available DAWN (R) row cleaners and different experimental residue managers on cotton (Gossypium hirsutum L.) stand, emergence rate, and seed cotton yield. Experimental residue managers consisted of two different ski-like devices (jointed and rigid) to press down the residue on each side of the planting path. Each type of pressing device was equipped with a V-shape divider or two different residue pushers to divide or to push down the residue. A randomized complete block design with four replications was used and results represent three growing seasons (2012, 2013, and 2014). Rye (Secale cereale L.) was the selected cover crop since it is popular among Alabama producers. Standing rye (without rolling down) was chosen to study treatment effects of the different residue managers. Rye was chemically terminated using Roundup (glyphosate), and after complete rye desiccation, cotton was planted directly into standing rye residue cover. During cotton planting, cover crop residue accumulation on the no till planter and the time required to clean residue from planting units were measured. In three growing seasons, treatments did not affect cotton yield: however, differing weather and residue amounts did affect cotton yield. Cotton population was affected by residue manager treatments in 2012, but not in 2013 or 2014. Significant population differences were observed between the three growing seasons, and cotton stand was significantly lower in 2013 due to large amounts of cover crop residue. The highest cotton population was observed in 2014 due to optimum soil moisture. In three growing seasons, residue management treatments affected residue amounts on planting units. The highest residue accumulation was observed with the V-type divider where rye was pulled because of winding weeds (hairy vetch) interlocking with stalks. The second largest residue accumulation was observed with the standard DAWN (R) row cleaners with coulters; this was due to rye residue wrapping around the rotating row cleaning wheels which required significantly more time for cleaning compared to the other residue managers. Compared to the commercially available standard DAWN (R) row cleaner, the custom residue managers performed successfully, especially in standing cover crops that had not lodged in different directions.