Nitrogen Rate, Cover Crops, and Tillage Effects On Continuous Long-Term Tilled and No-Tilled Cotton.

The highly erodible loess soils of West Tennessee had been intensively cropped using conventional tillage systems including deep tillage since the early 1800’s.  This resulted in severe soil losses due to water erosion.  The use of soil conserving practices such as cover crops and no-tillage were very much needed, especially in low residue cotton production.  In 1979, a long-term experiment was established on a Lexington silt loam (Ultic Hapludalf).  The objectives were to investigate the effects of nitrogen rate, cover crops, and tillage on soil quality and cotton yield.  The experimental design was a randomized complete block with a sub-subplot design with four replications.  The main treatment was nitrogen rate with cover crop as the sub plot and tillage as the sub-subplot.  Nitrogen rates were 0, 34, 67, and 101 kg/ha, sub plots were hairy vetch, crimson clover, wheat, and no cover, and the sub-subplots were tilled and no-tilled.  Results indicated a fertilizer nitrogen equivalency of 67-90 kg/ha to the cotton crop when planted into the incorporated or non-incorporated nitrogen fixing legumes of crimson clover or hairy vetch. Cotton yields were general not significantly different between no-till and tilled systems.  The use of cover crops and no-tillage were shown to be practical and no-tillage cotton is now widely adopted in Tennessee.