Crop management factor model solution by digital computer

Protecting resource base requires developing specific management systems that will control erosion and yet allow adequate and profitable crop production. In addition, models that compute the economic impact of soil loss legislation and policies require accurate soil loss predictions if realistic results are to be obtained. The most frequently used tool for estimating soil loss equation. Estimating soil loss under a specific management system is highly dependent on accurately calculating the crop management factor. Crop management factor model and its solution by digital computer. The system has been in use since 1981. The rudiments of a subfactor approach to computing soil loss ratios were presented by W.H. Wischmeier in 1973. Shortly there after, in 1974, the first author developed a simple subfactor system. Initial testing and calculations were by hand calculation, and for some time the simple system was operated on small desk-top calculator. The current model is considerably more complex than the initial system, and is operational in Basic and Fortran on personal and larger computers. The model tallies the location and quantity of residue from the time of harvest as it decomposes or is mixed into the soil by tillage implements. Surface and incorporated residue factors are computed. Crop growth is entered and a cover factor is calculated. Surface roughness and detachability factors are entered as components of the model. Antecedent moisture level is assigned prior to the erosion season and a soil moisture factor is changed in response to rainfall input. The model has been used for calculating crop management factors for the U.S. Soil conservation Service for non-irrigated cropland of the Northwest Wheat and Range Region of the United States since 1981. It has also been used in numerous studies of the economic impact of various conservation policies and programs.