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B-21 is a version of PC-LP, a computer based farm planning model. This version of PC-LP can be used to help you answer at least four types of questions about the best use of your crop farm resources: namely,
1. Timeliness — Do you have enough labor and the right size machinery? 2. Crop Rotation — Are you growing the most profitable acreage of each rotation?
3. Technology or Tillage System — Do you use the right technology or tillage system?
4. Farm Size — Should you change the number of acres that you farm? Using linear programming, the computer will combine the land, labor, machinery resources, and crop alternatives you indicate to farm your acreage in the most profitable way. Subject to any limiting conditions you describe, the computer determines your best crop mix, the combination which maximizes the returns to your resources. By comparing solutions with different farm sizes, machinery and labor complements, crop yields, costs and prices, you can select your best plan. In B-21, the authors have already set the time periods and the crops you might consider. By completing this Input Form, you will describe the resources that you have available, you will specify your crop rotations, you will describe your tillage systems, and you will indicate your expected crop price, crop yields, and cost of production. The computer is programmed to keep a file of the farm data you provide in this input form. To make additions, change your answers in another input form (available at the workshop). Data entry persons will then change your file and re-solve your plan. To learn the effect of each change, make only one or a few changes per input form. For some questions, example numbers are shown in parentheses. These are presented to guide you as you answer the questions. They are not included as default data in the program. If you do not place a number in a blank, it will be treated as zero.
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D. H. Doster, C. L. Dobbins, G. F. Patrick, W. A. Miller, and P.V. Preckel
July 2006
To be a competitive crop producer, you must use your limited land, labor, and machinery resources efficiently. Based on the data you provide, B-21 carefully calculates the possible ways that your resources can be used and selects the way that will provide the largest return to your present land, labor, and machinery resources. In allocating your land, labor and machinery resources to the most profitable crop production alternatives, differences in the direct costs of production (fertilizer, seed, chemicals, etc.), differences in yield related to plant-harvest date and differences in amount and timing of machinery and labor needed are recognized. You can describe your farm in B-21 by entering the quantity of land, labor and machinery resources available, and the methods you use to produce crops. To use the model to explore alternative problem solutions, you will first want to be sure that your current situation is accurately represented. The accuracy of your representation can be tested by providing the requested data and then reviewing the model results. The results you obtain should indicate average yields similar to those you receive. The results should also indicate that planting and harvesting are completed at the times you are typically finished. The results will not match any specific year, but should represent the typical case. If the model results differ from those you experience in real life, you will need to change one or more input entries. After you have developed a realistic representation of your current situation, you can use B 21 to assess many alternatives:
1. How might changing your crop mix affect your farm business?
2. How might reducing some of your tillage operations or a shift to a reduced tillage production system affect your farm business?
3. How might working additional hours or hiring part-time labor during the spring and fall affect your farm situation?
4. How would purchasing a larger planter or combine affect your farm situation?
5. How would adding more land through rental or purchase affect your crop mix and machinery resource requirements?
6. How would purchasing a drill and planting corn and soybeans at the same time affect your farm situation?
7. How would adding auto-steer technology affect timeliness? For each situation you choose to investigate, B-21 will select the combination of crops and the acreage of those crops that provides the maximum return to your land, labor and machinery resources.
D. H. Doster, C. L. Dobbins, T. W. Griffin, & B. Erickson
Juen 2010
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