Temporal and spatial simulation of production-scale irrigated cotton systems

Site-specific management of cotton (Gossypium hirsutum) cropping systems at the production-scale requires information regarding environmental interactions across the landscape. Landscape-scale cotton models could track these interactions and be integrated into future decision support tools designed to manage variable inputs; however, modeling of cotton systems across the landscape has not been evaluated. Cotton production in the Southern Texas High Plains is dependent on irrigation from the Ogallala Aquifer, and thus tracking soil water content across fields could help producers plan their use of diminishing aquifer resources. Our hypothesis was that the PALMScot model, a grid-based landscape-scale cotton model, would capture spatial and temporal variability and environmental interactions affecting soil water and plant growth within a 70-ha field throughout two contrasting growing seasons, without adjustment of input parameters for the model. Thus, our objective was to compare values of soil water content and crop height calculated by the PALMScot model with corresponding field measured values at multiple locations across a fine textured, pivot irrigated production cotton field during two growing seasons. The PALMScot model calculated values of soil water and crop height across the field with a root mean squared deviation (RMSD) for soil water content in the 1.0-m profile a parts per thousand currency sign0.032 m(3)/m(3) and most Nash-Sutcliffe efficiency (NSE) values a parts per thousand yen0.48. Values of RMSD for crop height were a parts per thousand currency sign0.10 m at all locations in 2010 and 2011. We conclude that PALMScot correctly and efficiently calculated soil water content and crop height across the field, throughout each season, and the model has potential as a site-specific management tool for cotton cropping systems.