Growth and agronomic performance of cotton when grown in rotation with soybean

Abstract

Mid-South United States (US) cotton producers are now rotating cotton (Gossypium hirsutum L.) with other crops such as corn (Zea mays L.) or soybean [Glycine max (L.) Merr.],in response to economic conditions, rather than growing cotton continuously as was the tradition. This research investigated cotton growth and development, lint yield, and fiber quality when cotton was grown following soybean compared to following cotton. Cotton and soybean were grown in six rotational sequences (CCCC, SSSS, CSCS, CSSC, SCSC, and SCCS) during 2012-2015 at Stoneville, MS. These rotations were imposed in production systems utilizing either transgenic or conventional cultivars, with or without glyphosate in the herbicide regime. Dry matter partitioning, leaf chlorophyll (Chl) concentration, lint yield, and fiber quality data were collected. Years when cotton was grown following soybean, produced cotton plants that were on average 13% taller, intercepted on average 6% more sunlight, and contained 13% greater leaf Chl concentrations compared to plants in continuous cotton. Cotton grown following soybean produced increased yields one of the two years. Fiber quality was not impacted by the different rotation sequences. Cotton grown in a conventional production system was competitive with that grown in a transgenic production system. The yield increase observed when growing cotton in rotation with soybean is possibly due to increased soil N via Nfixation from the prior soybean crop and/or due to altered soil microbial populations favorable to the subsequent cotton crop.