| Abstrakt: |
Due to the increasing demand and limited supply of groundwater from the Ogallala aquifer, water use efficiency and agricultural water savings policies are at the forefront in the Texas High Plains. The objective of this field experiment was to determine yield and seasonal irrigation water use efficiency (SIWUE) of continuous cotton and cotton/sorghum rotations while evaluating three "water saving" strategies with annual irrigation depths limited to less than 5 inches per year. The experiment was conducted from 2004 to 2007 at the Texas AgriLife Research Center at Halfway. The continuous cotton and the cotton/sorghum rotation treatments were composed of the cropping sequences CCC - continuous cotton, CCS - cotton followed by cotton and sorghum, CSC - cotton followed by sorghum and cotton, and SCC - sorghum followed by two years of cotton. The irrigation strategies were; T1 - water applied to insure crop establishment, no in-season irrigation, any remaining water up to the five inch limit is "saved"; T2 - five inches of annual irrigation applied only if soil water content at planting was greater than 50% of field capacity, otherwise, the water is "saved"; and T3 - five inches of annual irrigation regardless of initial soil water content. Over the 4-year period, the T1 treatment resulted in average annual cotton yields ranging from 674 to 719 lb lint/ac with total irrigations of 0.8 inches; T2 resulted in yields ranged from 905 to 951 lb lint/ac with irrigations of 3.04 to 3.35 inches; and T3 resulted in yields ranged from 1021 to 1050 lb lint/ac with total annual irrigations of 4.53 to 5.22 inches. By evaluating treatments using gross return including residual water valued at $12/ac-in, water savings in the T1 treatment did not compensate for the increase in value from crop sales received by applying additional irrigation in the T2 and T3 treatments. The continuous cotton treatment resulted in higher gross returns within each strategy than did the cotton-sorghum rotation treatment. SIWUE of strategies T2 and T3 exceeded normal water use efficiency levels by 44 and 126%, respectively, over the 4-year test period. Additional economic evaluations will be made in the future. [ABSTRACT FROM AUTHOR] |
