Texas Agricultural Experiment Station researchers are now pondering whether crop rotation can add value to irrigation water and help maintain or improve yields in limited irrigation situations, along with other benefits like yield improvement, reduction of erosion and insect and disease management.
Jim Bordovsky, experiment station ag engineer, and other scientists are investigating the feasibility of producing cotton and grain sorghum in rotation using dryland production strategies supplemented by limited irrigation using efficient delivery systems.
Each year's crop rotation treatments included cotton-cotton-grain sorghum, cotton-grain sorghum-cotton, and grain sorghum-cotton-cotton. These treatments were compared to a three-year cycle of continuous cotton.
Study results to date show the cotton-grain sorghum treatments consistently increased cotton yield compared to continuous cotton.
In the harshest year, 2003, their cotton-grain sorghum rotation yields were 26% higher than continuous cotton yields, used 19% less water and required less tillage to prevent blowing sand.
“Our seasonal irrigation water-use efficiency was highest in rotations where cotton followed grain sorghum,” Bordovsky says. “But there is a real risk with rotations under dryland conditions. In low rainfall years such as 2002 and 2003, we didn't produce any harvestable grain, and we didn't see any real cotton yield benefit from the grain sorghum residue.”