Winter Cover Crop Effect on Nutrient Cycling for Cotton

Use of winter cover crops can provide supplemental nutrients to a subsequent cash crop, in addition to increasing organic material in the soil profile.  An experiment was conducted in 2009-2010 at Tifton, GA to assess the nutrient cycling of several winter cover crops in conventional and strip-tillage management on cotton.  The factorial arrangement of treatments included conventional vs. strip-tillage and four winter cover crop treatments (crimson clover, rye, wheat, or no cover).  All plots were fertilized in-season following the Extension guidelines.  Results show that larger biomass quantities and in some cases higher nutrient concentrations caused more total release of N, P, K, Ca, and Mg from crimson clover residue compared to rye or wheat.  This resulted in greater total nutrient content in the cotton plant for N, K, and Mg following crimson clover in 2009.  However, there were no nutrient content differences in cotton tissue in 2010 for any cover crop treatment.  There was also a significant difference in plant height in 2009, with taller cotton plants in crimson clover plots.  Crimson clover plots likewise caused an 8-16% reduction in yield (P<0.10) in 2009, and had 7-11% lower micronaire value than the cotton following the other cover crop treatments that year.  No differences in yield or any fiber quality measures were observed in 2010.  Based on these results, the nutritive value of cover crops can play a role in nutrient availability and uptake by the cotton plant, but must be managed appropriately in accordance with sidedress fertilization and other management strategies (such as application of a plant growth regulator) to prevent excessive vegetative growth of the cotton and potential yield loss.