When times are tough, farmers try to lower their fixed and variable costs. Fixed costs are relatively inflexible and often hard to reduce. They can be controlled somewhat by improving efficiency and by making decisions such as maintaining a functional piece of equipment rather than purchasing a new one. Many farmers may target variable costs, such as fertilizer, for cost reductions. However, before cutting down on phosphate (P) and potash (K) use, farmers should carefully evaluate their soils and fertility program. Nitrogen, P and K account for a high percentage of current crop yields and are critical to successful farming operations. Those who fine-tune their system for maximum economic yields maximize their profits in good times and minimize their losses in bad times.