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Title: CONSERVATION SYSTEM IMPACTS ON COTTON WATER RELATONSHIP AND PRODUCTIVITY AT THE LANDSCAPE LEVEL

Author
item TERRA, J - AUBURN UNIVERSITY
item Reeves, Donald
item SHAW, J - AUBURN UNIVERSITY
item VAN SANTEN, E - AUBURN UNIVERSITY
item MASK, P - AUBURN UNIVERSITY
item Raper, Randy

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 10/30/2003
Publication Date: 1/8/2004
Citation: Terra, J.A., Reeves, D.W., Shaw, J.N., Van Santen, E., Mask, P.L., Raper, R.L. Conservation system impacts on cotton water relatonship and productivity at the landscape level. National Cotton Council Beltwide Cotton Conference. 2004. p. 2581-2582.

Interpretive Summary: How soil management practices impact cotton productivity across landscapes is not understood. ARS scientists at the J. Phil Campbell Sr. Natural Resource Conservation Center, Watkinsville, GA and the Soil Dynamics Research Unit in Auburn, AL, cooperated with Auburn University scientists to determine the impact of conservation practices on yield, soil water, and indicators of drought stress for cotton grown in a 20 acre field in Alabama. Practices evaluated were a conventional system and a conservation system; both with or without dairy bedding manure. In the conventional systems, tillage consisted of chisel plowing/disking + in-row subsoiling; no cover crop was used in winter. Conservation systems consisted of only non-inversion in-row subsoiling plus winter cover crops to provide 4 to 6 tons/acre of residue for complete soil coverage. Management practices were arranged so as to cross the maximum landscape variability in the field. Manure had no effect on cotton yield and drought stress indicators. Conservation systems had greater rainfall infiltration, improved water use efficiency and less drought stress, and 14% higher yield (2430 lb seed cotton/acre)than conventional systems. The study showed conclusively, even at the scale of operations used by producers, that conservation systems using no-tillage and high-residue producing cover crops minimized drought stress, reduced economic risks from yield variations, and increased cotton yields. This information can be used by extension specialists, USDA-NRCS, crop consultants, and producers to promote the use of environmentally and economically sustainable conservation practices on the 4.2 million acres of cotton grown in the Southeast.

Technical Abstract: Conservation tillage systems can improve soil quality, crop water use efficiency and productivity. However, how these systems interact with soil variability across landscapes to impact cotton productivity has not been evaluated. We evaluated the effects of soil management practices on yield, volumetric soil water content SWC), stomatal conductance (SC) and leaf canopy temperature (TEMP)during bloom of cotton grown in a 24 acre coastal plain field in AL. Treatments were established in a RCB design with 6 replicates in strips traversing the landscape in a corn-cotton rotation. Treatments included a conventional system with or without dairy bedding manure, and a conservation system with and without manure. In conventional systems, tillage consisted of chisel plowing/disking + in-row subsoiling; no cover crop was used in winter. Conservation systems consisted of no surface tillage with non-inversion in-row subsoiling and winter cover crops. Data were analyzed with mixed models accounting for spatial correlation with the modeled semivariogram. Manure did not affect response variables. Conservation systems had greater SWC, higher SC and lower TEMP compared to conventional systems. Data suggested a better partitioning of evapotranspiration and greater water infiltration in conservation systems compared with conventional systems; consequently, less crop water stress. Averaged over years, conservation systems improved seed cotton yield 14% compared to conventional systems. For degraded soils in the Southeast, conservation systems including no-tillage and high-residue producing cover crops minimize drought risk and increase cotton yield and yield stability.