In an IFSM simulation, crop production, feed use, and the return of manure nutrients back to the land are simulated over many years of weather. Growth and development of alfalfa, grass, corn, soybean, and small grain crops are predicted on a daily time step based upon soil water and N availability, ambient temperature, and solar radiation. Performance and resource use in manure handling, tillage, planting, and harvest operations are functions of the size and type of machines used and daily weather. Field drying rate, harvest losses, and nutritive changes in crops are related to the weather, crop conditions, and machinery operations used. Losses and nutritive changes during storage are influenced by the characteristics of the harvested crop and the type and size of storage facility used.