Net returns are very sensitive to relative yield levels of the different crops. Corn yields in the state have probably fluctuated most widely in recent years. Our annual crop budgets break down fixed and variable costs based on standard accounting methods. Fertilizer is a good example - if you don't produce a crop, you don't need any fertilizer. Fixed costs will be incurred even if production doesn't occur.
Depreciation is the classic example.
Seed that has been saved back from the previous crop. Residual fertilizer that has been applied. Full-time labor that is underutilized. Land costs, prior to renting or purchasing. Depreciation and interest on machinery that must be purchased, e.g., if you are going to have to buy a cotton picker or module builder to make a crop.