Submitted to: Weed Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/3/2006
Publication Date: 7/1/2006
Citation: Reddy, K.N., Locke, M.A., Koger III, C.H., Zablotowicz, R.M., Krutz, L.J. 2006. Cotton and corn rotation under reduced tillage management: impacts on soil properties, weed control, yield, and net return. Weed Science 54:768-774. Interpretive Summary: Profit margins in cotton production have declined in recent years and crop production systems that increase yields without increasing production costs needs to be developed. Scientists at the Southern Weed Science Research Unit in Stoneville, MS completed a 6-yr study that examined the effects of rotating roundup ready (RR) and non-RR (conventional) cultivars of cotton with corn under reduced tillage on soil properties, weed control, crop yield, and net return. A glyphosate-based program in RR cultivars and a non-glyphosate-based program in non-RR cultivars were used for weed control. Soil organic carbon in top soil increased from the first year to the sixth year, regardless of rotation with higher organic carbon accumulation under continuous corn compared to continuous cotton. Most common grass and broadleaf weeds were controlled sufficiently to support cotton and corn production, regardless of rotation and herbicide program. Cotton stand of both RR and non-RR cotton rotated with corn were similar to that of continuous cotton suggesting stand establishment was unaffected by corn residues. Cotton yield and net return increased every year following rotation with corn compared to continuous cotton. Similarly, corn yield and net return increased when rotated with cotton. These findings demonstrate that cotton rotation with corn is a practical and a profitable option for farmers in the lower Mississippi River alluvial flood plain region.
Technical Abstract: A 6-yr rotation study was conducted from 2000 to 2005 at Stoneville, MS to examine the effects of rotating glyphosate-resistant (GR) and non-GR (conventional) cultivars of cotton with corn under reduced tillage conditions on soil properties, weed control, crop yield, and net return. There were four rotation systems (continuous cotton, continuous corn, cotton-corn, and corn-cotton) for each non-GR and GR cultivar arranged in a randomized complete block design with four replications. Field preparation consisted of disking, subsoiling, disking, and bedding in the fall of 1999. After the fall of 2000, the experimental area received no tillage operations except re-bedding after harvest each year to maintain reduced tillage conditions. A glyphosate-based program in GR cultivars and a non-glyphosate-based program in non-GR cultivars were used for weed management. Soil organic carbon in the top 5-cm depth progressively increased from the first year to the sixth year, regardless of rotation. In 2005, organic carbon was higher in corn grown continuously and in rotation compared to continuous cotton, partly due to higher plant residues from corn compared to cotton. Control of most grass and broadleaf weeds was sufficient to support cotton and corn production, regardless of rotation and herbicide program. Control of yellow nutsedge was reduced in continuous non-GR cotton; this apparent weed species shift towards yellow nutsedge was mitigated by breaking the cotton monocrop with corn. Plant populations of both GR and non-GR cotton rotated with corn were similar to that of continuous cotton suggesting cotton stand establishment was not affected by corn residues from the previous year. Cotton yield increased every year following rotation with corn by 10 to 32% in the non-GR cultivar and by 14 to 19% in the GR cultivar compared to continuous cotton. Similarly, corn yield increased by 5 to 13% in non-GR cultivar and by 1 to 11% in the GR cultivar when rotated with cotton. As a result, net returns were higher from rotation management as compared with monoculture in both crops. This study demonstrated that alternating between cotton and corn is agronomically feasible and a sustainable option for farmers in the lower Mississippi River alluvial flood plain region who are looking for simple cultural practices that provide economic and environmental benefits.