Sustainable Cotton Production for the South
The 1996 centennial of Alabama’s Old Rotation (circa 1896) experiment marked a milestone in the use of winter legumes (annual clovers and vetch) as a source of nitrogen for nonleguminous cash crops such as cotton and corn. The Old Rotation is the world’s oldest, continuous cotton experiment and the third oldest field crop experiment in the United States on the same site.
When it was started in 1896, its primary purpose was to determine the effect of crop rotations and winter legumes on sustainable production of cotton in the southern U.S. However, growers, for whatever reason, have been reluctant to adopt these well demonstrated, sustainable practices which protect the soil from winter erosion and add N to the soil. Perhaps inexpensive N fertilizers, traditional tillage practices and the nature of the growers winter legumes have made this practice unattractive.
1) Use the concepts of sustainability as illustrated in the 98-year Old Rotation to conduct on-farm sustainable cotton production demonstrations.
2) Prepare research bulletins and popular brochures on the benefits of sustainability as demonstrated by 98 years of continuous, sustainable cotton production and on-farm demonstrations.
3) Compute cotton sustainability and total social factor productivity indices in order to assess the ability of cotton to remain a viable economical and environmentally compatible crop for Alabama.
4) Conduct workshops for county agents, providing training necessary to conduct on-farm sustainable production demonstrations.
An extensive demonstration of new legumes as a source of N for cotton was established in Central Alabama in the fall of 1995 and will continue through 1997. This site was a feature in the 1996 Central Alabama cotton tour where more than 100 growers participated.
The results from this replicated demonstration indicated that legumes were just as effective as the recommended rate of fertilizer N on seed cotton yields. The new legumes do not appear to be any better than the older ones such as hairy vetch in sustaining cotton yields. Three additional on-farm demonstrations were established in the fall of 1996.
Impact of Results
A seminar and a one-day symposium celebrating 100 years of sustainable cotton production in the South was held on the campus of Auburn University in conjunction with the centennial of the Old Rotation. Speakers from England (Rothamsted Experiment Station), Illinois, Missouri, and Oklahoma complemented presentations from Alabama research and extension programs. More than 100 growers, researchers, extension specialists and agribusiness leaders attended the program which included tours of long-term cotton and winter legume plots. This complemented four in-service training sessions held around the state in 1996 on sustainable agriculture systems
Analysis of long-term data provides convincing evidence that continued use of winter legumes with or without crop rotations in a cotton production system can improve soil quality as measured by soil organic matter. Cotton yields are highly significantly related to soil organic matter.