DRYLAND CROPPING SYSTEMS TO ENHANCE SOIL MOISTURE CAPTURE AND WATER-USE EFFICIENCY IN COTTON

摘要

Rainfall is the most limiting factor in dryland cotton production in the Texas Rolling Plains. Cropping systems that enhance rainfall capture and storage during the season offer the most promise for increased dryland cotton yield. This project was initiated in 2001 to study cropping systems that offer a means to capture limited rainfall other than furrow-diking and at the same time offer seedling cotton protection from blowing sand. This research (in its second year) was conducted at the Chillicothe Research Station on a Abilene clay loam. The objectives were to (1) compare rainfall capture and soil moisture profiles in five cropping systems that include conventional tillage, reduced-till, reduced-till with dikes, strip-till with interseeded rye,and no-till with interseeded rye, (2) determine the effects of different cropping systems on plant yield response and lint quality, and (3) develop educational programs to disseminate information obtained from this research. The test contained three replications of each cropping system. In the strip-till and no-till plots, two rows of rye (7.5-inch spacing) were planted each fall between the future cotton rows. Rye was terminated at 50% heading the following April with Roundup Ultra. Paymaster 2280 RR/BG was planted mid-May of each year at 4 seeds per foot of row on 40-inch rows. Shortly after emergence soil moisture probes were placed at 1-foot and 3-foot depths within plots to determine soil moisture extraction profiles over the season. Soil moisturereadings were taken weekly until cotton matured. A runoff collection system was installed mid-May to collect rainfall runoff from three systems: conventional, strip-till with inter-seeded rye, and reduced- till with furrow dikes. Sediment load in the runoff was also determined. The 2001 growing season was extremely dry and hot, whereas the 2002 growing season was more normal with respect to rainfall amount and temperature. Dryland yields in 2002 were nearly double those of 2001. In 2001, the furrow-diked and the strip-tilled with rye systems were numerically the last to dry out at the 3-ft depth. In 2002, the no-till with rye, strip-till with rye, and furrow-diked systems contained more soil moisture at the 3-ft depth at the end of the growing seasonthan the conventional-till and reduced-till systems. Surface water runoff was recorded following each rainfall event that produced runoff. No rainfall event in either year resulted in substantial runoff. Nevertheless, there were differences in runoff amounts even though not all differences were significant. The conventional-till system resulted in the greatest amount of runoff and sediment displacement. In 2002, the strip-till with interseeded rye resulted in the least runoff and greatest reduction in sediment load. This system appeared to be even superior to the diked system. The runoff results are encouraging in that the strip-till with rye system approached, and may exceed, that of furrow-diking with respect to rainfall capture. Lint yields were notsignificantly affected by any system. This is encouraging as the strip-till with rye and no-till with rye systems require fewer field operations than conventional or diked systems and may result in greater economic returns while providing seedling protection from wind as well as conservation of soil resources.