Submitted to: Cotton Research and Extension Report
Publication Type: Experiment Station
Publication Acceptance Date: February 15, 2009
Publication Date: March 15, 2009
Citation: Bergtold, J.B., Monks, C.D., Balkcom, K.S., Raper, R.L., Arriaga, F.J. 2009. Agronomic and economic impact of timing for planting and defoliation of cotton on cotton yield, quality, and profitability. 2008 Cotton Research and Extension Report. No. 33. p. 17-19. Technical Abstract: This experiment was initiated in the fall of 2006 at the E.V. Smith Research Center, Field Crops Unit near Shorter, Alabama, on a Compass sandy loam (coarse-loamy, siliceous, subactive, thermic Plinthic Paleudults). The experiment was rotated to a different location each year, but the soil type was the same. The experimental design contained a strip-plot treatment restriction in a randomized complete block design with three replicates. The horizontal plots consisted of three planting dates, and the vertical plots were defoliation times that corresponded to 40, 60, 80, and 100 percent open boll. A rye cover crop was drilled across the experimental area each fall at 90 pounds per acre. An in-row subsoiling operation was performed, prior to each planting date, with a KMC (Kelly Manufacturing Company) Rip Strip®. Four rows of the subsequent plots were harvested with a spindle picker equipped with a bagging attachment approximately two weeks following defoliation. A large sub-sample (approximately 50 pounds) was sent to the University of Georgia’s Micro-Gin Facility to determine ginning percentages. After the ginning process, another sub-sample of the lint from each plot was sent to the USDA Classing office in Macon, Georgia, to determine cotton quality from all plots with HVI-fiber analysis. At this time, a complete data analysis that includes fiber quality is only available for the 2007 growing season. An interaction (Pr> F = 0.0003) was observed between planting dates and defoliation percentages for cotton lint yields. This interaction can be attributed to 33 percent lower lint yields measured from the second planting date compared to the first and third planting dates. Cotton lint yields were more variable across the different defoliation percentages from the first planting date compared to lint yields across defoliation percentages for the third planting date. These yields indicate that for early planted cotton, there may be a yield advantage to defoliating the cotton slightly later. Length, micronaire, and strength were only affected by planting date in 2007, but planting date affected the fiber properties differently. In conclusion, one year of data collection for fiber properties that were influenced by the environment limit the scope of these results. However, combining these results across multiple years should allow trends to become more apparent and enable different management strategies to be tested across various climatic and market conditions.