The weather variability in Texas causes difficulties on the decisions of when and what the crop management should be used for a specific task. For example, irrigation, defoliation, fertilization, pest management are all influenced by weather. Thus a program of crop simulation models was designed to aid in agricultural decisions and lead growers to use managements practices taking into account environmental factors. The goal of this work is the validation of a simulation model by comparing measured and simulated values for three years of experimental data obtained in Helms, TX. We compare measured and simulated values of canopy development, water use and soil moisture in an irrigated cotton crop.