Assessing the Feasibility of Growing Cover Crops in Cotton Production Systems of the Texas Rolling Plains

The Texas Rolling Plains are predominately made up of monoculture cropping systems, with cotton and wheat accounting for over one million hectares. There has been an increasing interest to grow cover crops in this region, mainly to build soil health. However, there are concerns that growing cover crops could potentially reduce soil moisture, and thereby affect subsequent cash crop yield. Previous field studies from this region demonstrated mixed results with some showing a reduction in cash crop yields due to growing of cover crops and others indicating no significant impact of cover crops on subsequent cotton lint yields. The objective of this study was to evaluate the effect of growing winter wheat as a cover crop on soil moisture availability for subsequent cotton crop using the CROPGRO-Cotton and CERES-Wheat modules within the Cropping System Model (CSM) of the Decision Support System for Agrotechnology Transfer (DSSAT). These two modules were calibrated using the measured data on soil moisture and crop yields from two treatments of cover crop field experiments (cotton with wheat cover crop and cotton without a cover crop) at the Texas A&M AgriLife Research Center at Vernon during 2011 and 2015. The simulated soil moisture in the top 140 cm soil profile and cotton and wheat yields matched fairly well with the measured data during the model calibration and validation. The simulated dates of onset of cotton and wheat phenological stages were also within the ranges of generally observed dates in this region. Long-term (1996-2015) simulations have been run with the calibrated model and the water balances under both systems (cotton with a terminated winter wheat cover crop and cotton without a cover crop) are being assessed currently. The soil moisture availability for cotton under various precipitation and temperature patterns over the simulation period has also been evaluated.