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

Authors: Pettigrew, William; Bruns, Herbert; Reddy, Krishna

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2016
Publication Date: 11/17/2016
Citation: Pettigrew, W.T., Bruns, H.A., Reddy, K.N. 2016. Growth and agronomic performance of cotton when grown in rotation with soybean. Journal of Cotton Science. 20:299-308.

Interpretive Summary: Fluctuating commodities prices and changes in farm program regulations have made it easier and often desirable for producers to shift the planting acreage among different crops in response to changing market conditions. Although much of the Mississippi Delta was traditionally planted with cotton, many of those acres are now planted in corn or soybean because of either improved market prices for those grain crops or to achieve crop rotational goals. This scenario of shifting crop acreage means that on many acres cotton will be grown following a prior soybean. Because of a lack of knowledge about how cotton responds when grown after soybean, ARS scientists in the Crop Production Systems Research Unit at Stoneville, MS conducted research to determine how the growth and development, yield, and fiber quality of cotton was affected when it was grown behind soybean compared to when it was grown behind cotton. When cotton was grown following a prior crop of soybean, the plants were taller, the canopy intercepted more sunlight, and the lint yields were greater than when cotton was grown following cotton. This positive cotton response could be due to improved soil nitrogen levels or altered (improved) soil microbial populations after growing soybean. As producers shifts their production acreage among various crops to maximize short and long-term profits for their farming operations, they can expect to observe improved good and yield production when cotton is grown following soybean. Agronomists, crop physiologists, extension personnel, and consultants, will be able to utilize information from this research. Producers could use this research as an unbiased source of information to make crop allocation and cotton production decisions for their farming enterprises.

Technical Abstract: Mid-South 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. The research investigated how cotton’s growth and development, lint yield, and fiber quality were impacted 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 from the plots. Years where cotton was grown following soybean produced cotton plants that were on average 14% taller, intercepted on average 10% more sunlight, and contained 13% greater leaf Chl concentrations compared to plants in continuous cotton. Cotton grown following soybean produced increased yields two of the three 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 N-fixation from the prior soybean crop and/or due to altered soil microbial populations favorable to the subsequent cotton crop.