Evaluating Stored Soil Moisture in Monoculture and Rotational Cropping Systems.

Within the Texas Rolling Plains and much of the Southern Great Plains, monoculture cropping systems are prevalent.  Even under no-till conditions, soil organic C levels have not significantly increased in continuous cotton cropping systems, even with the addition of cover crops.  Our objective is to determine cropping systems that will improve water holding capacity and reduce irrigation demands in semi-arid environments. We are evaluating continuous cotton cropping system and a cotton/sorghum rotation in a subsurface drip irrigation system. For each system, five tillage strategies are being evaluated: 1) conventional tillage; 2) strip-till; 3) no-till; 4) no-till with a wheat cover crop; and 5) no-till with a mixed species cover crop. Neutron probes are installed in each plot and read bi-weekly throughout the year.  Data are being tabulated at this time; however, past research has indicated better water capture under no-till systems compared with conventional till systems. In addition, lint yields have been greater in rotational systems than continuous systems.  Water extractable organic C levels have also increased more rapidly under the sorghum/cotton rotation system than the continuous cotton system with cover crops.