Cropping or crop removal is a soil depleting activity. There is no free lunch. Proper fertility management, including an adequate liming program, is the key to optimum economic yields. Proper fertilization of alfalfa allows for good stand establishment and promotes early growth, increases yield and quality, and improves winter hardiness and stand persistence. Adequate fertility also improves a forage's ability to compete with weeds and strengthens disease and insect resistance.
Fields differ in their fertilizer needs.
Soil testing is the most convenient and economical method of evaluating the fertility levels of a soil and accurately assessing nutrient requirements. Either take a new look at your old sample results or take a new sample. The sample should portray a representative area. That is, the sample should not include old fence lines, borrow pits any place different from the average, good or bad. Also, try to keep each sampled area at less than 10-15 acres.