Agronomic Performance of Cotton Grown Under High Rye Biomass Cover Crop

Cotton growth, development, and yield were evaluated under different tillage and irrigation practices in Camilla, GA during 2013 and 2014.  Two tillage treatments, conventional and conservation including a high biomass rolled rye cover crop, and four irrigation treatments, 100, 75, and 50% of UGA checkbook recommendations and non-irrigated, were included.  Locations in Moultrie and Vienna, GA were added in 2014 and included only tillage treatments.  Increases in plant height, nodes above white flower (NAWF), and lint yield resulted from conventional tillage at Camilla in 2013, with heights and NAWF generally increasing with increases in irrigation up to 75% checkbook.  Irrigation had no effect on lint yield, likely due to excessive rainfall that occurred throughout the season.  At Camilla in 2014, early season plant heights increased as a result of conventional tillage, while later in the season heights were greater under conservation tillage.  Conservation tillage also increased NAWF, though there was no tillage effect on lint yield.  Increases in irrigation resulted in increases in plant height, NAWF, and lint yield, but there was typically no difference between 75 and 100% checkbook irrigation.  No significant differences in any parameter were present at Moultrie.  The results from the Vienna location were similar to those at Camilla 2013, with increased plant heights and NAWF observed in conventional tillage, while lint yield was not affected.  The lack of interaction between tillage and irrigation in both years of the Camilla study, along with the varying effect of tillage across all locations, illustrate that the potential benefits of a conservation tillage system utilizing a high biomass rye cover crop will be dependent on environmental conditions year to year.  The magnitude of the benefits is likely dependent on the quantity of rainfall received or irrigation applied, with little to no benefit when water is not limiting or excessive.