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Fluid Journal : Summer 2014
14 The Fluid Journal Summer 2014 0 800 0 8 Figure 4. Cotton water use efficiency Dr. Krieg is Professor Emeritus-Crop Physiology at Texas Tech University. pollination of an individual fruit are also very sensitive to both water and nutritional stress, resulting in a reduction in seed number per fruit (less seed results in less lint/boll) or fruit abortion. Daily water use for a cotton crop grown in West Texas during the 2013 season is depicted in Figure 3. Analyses of cotton yield components and water supply during development were conducted over a 10-year period, which included irrigated and dryland production. Regression analyses were used to determine the impact of water supply during each component’s development. The regression coefficients obtained revealed that the water supply from floral bud initiation through peak flower (about a 50 to 60 day period) had the largest impact on total yield, boll number, and boll size. Managing the total water resource during this critical period maximizes water use efficiency and yield. Efficiency. Water use efficiency of cotton can be defined biologically and economically. The biological water use efficiency for cotton grown in West Texas is depicted in Figure 4. Cotton requires about four inches of water use by the crop to get large enough to produce the first increment of harvestable yield. As the water supply increases, cotton produces about 100 to 125 pounds of seed cotton (45 to 50 pounds of lint) per inch of additional crop water use. As the water supply continues to increase, water use efficiency increases, attaining a maximum of 220 to 240 pounds of seed cotton (90 to 100 lbs of lint) per inch of crop water use with 22 to 25 inches of total crop water use. Cotton water use efficiency expressed on an economic basis ranges from $40 to $45/inch of water consumed at relatively low water supplies (<15 inches) to $75 to $85/inch at optimum water supplies (24 to 26 inches) and proper water management during the growing season (lint value = $0.75/lb and seed value = $160/ton). Irrigation pumping costs vary significantly across the West Texas Region, ranging from $5 to $10/acre inch, depending on pumping depth and pump plant efficiency. It is obvious that irrigated cotton production in West Texas can be a very profitable enterprise when adequate water supply is available. Other irrigated crops grown in this area either require greater amounts of irrigation water or have lesser value for the product. Summing up Cotton is the major crop grown in Texas due to its ability to be productive and profitable under water limiting conditions found throughout the state at certain critical times of the growing season. As the irrigation water supply, especially in West Texas, becomes more limiting, cotton production will remain as the major cash crop grown. Technology is available to greatly increase irrigation water application through reduction of surface evaporation. This technology is rapidly being adopted and will extend the life of the aquifer for West Texas cotton production. Act Now! Join The Fluid Fertilizer Foundation Joining Hundreds of Other Growers, Dealers, Fertilizer Mfrs., and Supporting Industries