Cotton was one of the first crops to be modeled with the objective of aiding profit-oriented commercial agribusiness. The GOSSYM-COMAX (Baker et al. 1983; McKinion et al. 1984; Sequeira and Jallas 1995) system is the only system currently being used in commercial agriculture. GOSSYM is a dynamic, daily simulation of the development and growth of the cotton plant. Baker et al. (1983), Jallas (1991) and Sequeira and Jallas (1995) published the descriptions of the theoretical background and most mathematical functions of GOSSYM. The model is divided into two daily, independent subsystems linked by a partitioning process. The first subsystem calculates the carbohydrate supply and the second subsystem calculates the carbohydrate demand. During each daily time step, the partitioning process –that drives the yield components and storage– balances the whole system. This explains the term "materials-balance" often used to describe this model.