| Abstrakt: |
During four years (2001-2004) the suitability of variable rate in a pivot irrigation system for cotton production was evaluated in the Texas High Plains (THP). The variable rate irrigation system delivers 75% ET replacement as the base rate (BR) and was compared to areas where BR-20% and BR+20% were applied. The effect of variable rate irrigation on water use efficiency (WUE), fiber lint yield and quality, and loan value were evaluated. Fiber quality parameters of interest were micronaire, strength, and length properties. In 2001 and 2003, BR+20% yielded more than the BR-20%, but micronaire was not affected by the water rate. Fiber strength improved with a decrease in water application in 2001, but was not affected in 2003. In 2002, the BR-20% rate was not evaluated, and BR+20% yielded more than the BR while fiber quality remained unaffected by irrigation rate. In 2004, due to excessive rainfall amounts, lint yield differences were not observed, but micronaire was negatively affected by increasing irrigation. Water use efficiency was only significantly different in 2003, where it increased with increasing water application. In each case and for every year, difference in fiber quality did not impact the loan value of cotton. Cotton, an indeterminate crop, seems too unpredictable to manage with variable rate irrigation especially under deficit irrigation practices and the short-growing season of the Texas High Plains. [ABSTRACT FROM AUTHOR] |
