 GOSIM is a process level cotton crop simulation model that uses a two-dimensional, 2D, gridded soil model called RISOs to simulate below-ground processes. It also uses a modified Farquhar biochemical model and Ball Berry leaf energy balance model to calculate photosynthesis and transpiration rates. GOSIM was tested against field scale and experimental data from SPA, Soil Plant Atmosphere Research, Chambers and Found to be more accurate than its predecessor at predicting net photosynthesis and transpiration rates as well as yield. This article was authored by Sahila Begum, Dennis Timling, Kambam Raja Reddy and others.