Effects of Combinations of Cropping Sequences and Biocovers on Yield of Glyphosate-tolerant Corn, Cotton, and Soybean under No-till.
Jennifer E. Noe1, F.L. Allen1, J.P. Wight1, and A.M. Saxton2. (1) Dept. of Plant Sciences, University of Tennessee, 2431 Joe Johnson Dr., Knoxville, TN 37996-4561, (2) Dept. of Animal Science, University of Tennessee, 2505 River Dr., Knoxville, TN 37996-4561
The amount of acreage under no-till is increasing in the United States as producers begin to recognize the environmental and economic benefits of these systems. Although the potential to receive carbon credits or payments for maintaining or initiating no-till may encourage producers to employ these practices, crop yields will be a factor in management decisions. Our objectives were to examine the effects of combinations of cropping sequences and winter bio-covers upon glyphosate-tolerant corn, cotton, and soybean yields under long-term no-tillage at two different locations in Tennessee. Research was conducted during the first 4-year phase (2002-2005) of a two-phase agronomic systems study (2002-2009) at the Middle Tennessee Research and Education Center (MTREC) in Spring Hill, Tennessee, and the Research and EducationCenter at Milan (RECM) in Milan, Tennessee. The experiment was a randomized complete block design with split block treatments, with the main plots consisting of 13 different cropping sequences of corn, cotton, and soybean at RECM and eight different cropping sequences of corn and soybean at MTREC. The subplots consisted of five bio-covers applied perpendicular to the cropping sequences. The bio-covers were fallow, hairy vetch, winter wheat, poultry litter, and canola. Rotated corn and soybean yields were comparable to or higher than their respective monoculture sequences at both locations. At RECM, continuous cotton yields averaged higher for the first three years but were comparable to or significantly lower than rotated cotton yields in the fourth year. At both sites, corn and soybean yields were highest under fallow and poultry litter, respectively. Cotton yields were highest under poultry litter bio-cover at RECM. Interactions between crop sequence and bio-covers at MTREC will be discussed. Results from the next four years of the experiment will provide more information on the long-term effects of crop sequence and bio-covers on corn, soybean, and cotton yields.