Production of Beef with Minimum Grain and Fossil Energy Imputs. Volume II. Discussion and Listing of the Model

摘要

The computer simulation model BEEF (Beef Energy and Economic evaluator for Farms) is used to determine minimum grain and fossil inputs in beef production. This model utilizes the System Dynamics (SD) approach to modeling and the GASP IV simulation language. The model components in SD consist of four basic expressions: levels, rates, auxiliaries, and constants. Flow diagrams and the sequence of computations used in SD are shown. An overview of the BEEF model is presented to provide an overall concept of the subroutine flow for seventeen activities including land taxes, paying hourly labor, machinery depreciation, income and expenses, purchases, sales, management decisions, and net worth of farms. Output from the model is tabulated in 24 categories covering land attributes, support systems, machinery, money accounts, notes payable and receivable, fertilizers, chemicals, present worth, and income statements. Tracing monitor outputs of management decisions are included. Descriptions of subroutines, complete listings of the BEEF model, data entry, FORTRAN listings of subroutines with variables used, and examples of output production strategies are contained in appendices.