MEMPHIS, Tenn. — Developing best practices for nitrogen (N) management is a “moving target” and requires continuous and coordinated research and Extension efforts. However, many research trials focus solely on cotton yield and quality and do not account for variations in soil type, environmental conditions, cropping systems (tillage, rotation, tillage, cover crop, etc.), irrigation, and preplant residual nitrates. Because of this exclusive focus on N rate, the vast majority of trials provide confounding results and do not identify the optimum rate that should be applied on a given farm with a specific soil type and cropping system.
In a new “Focus on Cotton” webcast on Grow: Plant Health Exchange, soil fertility and plant nutrition expert Bhupinder Singh Farmaha, Clemson University, reports results of a multistate project started in 2020 to improve understanding of soil biophysical properties in predicting cotton yield and quality response to N application rate. Nitrogen rate response trials were established using different N rates. Rates and sites were selected based on the local conditions and history of previous positive cotton yield responses to N applications. In 2020, at 10 of 22 sites, lint yield responded nonsignificantly to N applications. These sites had large variations in lint yield, with the mean site yield varying from 445 to 1,451 lbs./acre. At the other 12 sites, a quadratic, curvilinear, or linear plus plateau response of lint yield to N applications was observed, and the profit-maximizing N rate at these sites varied from 31 to 136 lbs./acre. The N factor (lbs. N/lb. lint) varied from 0.03 to 0.20 across sites.
The results from this study warrant including information from soil biophysical properties in making N recommendations to determine where to apply N and how much to apply. Following the revised N guidelines will help to increase farm profits and improve the environmental sustainability of cotton production.
This 43-minute presentation is freely available through the “Focus on Cotton” resource on Grow: Plant Health Exchange—an outreach service of The American Phytopatholgical Society that contains more than 400 webcasts, including presentations from a number of conferences. These resources cover a broad range of aspects of cotton crop management: agronomic practices, diseases, harvest and ginning, insects, irrigation, nematodes, precision agriculture, soil health and crop fertility, and weeds. These webcasts are available to readers open access (without a subscription).
The “Focus on Cotton” homepage also provides access to “Cotton Cultivated,” a resource from Cotton Incorporated that helps users quickly find the most current cotton production information available. These and other resources are freely available courtesy of Cotton Incorporated at www.planthealthexchange.org/cotton/Pages/default.aspx.
To learn more, watch Refining Cotton Nitrogen Recommendations on Grow: Plant Health Exchange.
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About Grow: Plant Health Exchange: Grow: Plant Health Exchange is a nonprofit, freely available, online resource of timely, science-based information on plant health. It’s a place for plant health management professionals to exchange knowledge and discover the latest applied research. Applied researchers generate the content for Grow, sharing their work and amplifying their reach, and plant health practitioners consume the content on Grow, relying on this user-friendly platform to provide proven plant health science. As an outreach service of The American Phytopathological Society, Grow serves the full range of professionals in plant health management.
About the Cotton Board: The Cotton Research & Promotion Act established the Cotton Board as a quasi-governmental, nonprofit entity to serve as the administrator of the Cotton Research & Promotion Program. Funded by America’s cotton producers and importers through the cotton check-off, the program’s research and promotion activities are conducted worldwide by Cotton Incorporated, the Cotton Board’s sole-source contracting organization, to increase the demand for and improve the market position of cotton.
The Cotton Research & Promotion Program continues to work in all areas of cotton’s pipeline—from the field to the consumer—to keep cotton the number-one fiber choice in the United States. For more information about the Cotton Board and the innovative activities stemming from the program, visit www.cottonboard.org.
–American Phytopathological Society
The Cotton Board