Carlos Fernandez
Texas AgriLife Research and Extension Center

Computer-assisted decision support systems can be useful tools in agricultural research and commercial crop management as they can help deal with environmental variability and the complex nature of soil-crop-pest-environment interactions. The simulation model CropWaterUse is a online tool included in the Crop-Weather Program, which is a Web-based decision support system developed for cotton growers farming in South Texas (http://cwp.tamu.edu). The model CropWaterUse was developed using a mechanistic modeling approach to simulate the progression of canopy development (height, leaf area index, and ground cover), crop water use (actual soil evaporation and canopy transpiration), soil moisture storage throughout the soil profile, relative plant-available soil water content and cumulative soil water deficit at root depth. This tool was designed to support management decisions in both rain-fed and irrigated cotton crops. Two studies were conducted to test the accuracy of CropWaterUse by comparing simulated values to measured water use and growth data. In one study, the measured water use consisted in continuous lysimetric actual evapotranspiration data. In the other study, actual water use was estimated using a water balance approach involving water input and soil water content. In both studies growth data consisted in non-destructive plant height and number of main stem nodes. Good agreement between simulated and observed values were obtained in both studies, which confirms that the CropWaterUse model is an accurate tool to simulate extended periods of crop water use in cotton.