Adding legumes such as clovers or alfalfa to grass pastures can provide multiple benefits, say University of Wisconsin Extension specialists. One is the ability of legumes to fix nitrogen, benefiting other plants in the pasture. If the pasture species composition is 30 to 50 percent legumes, research has shown there is no benefit to adding additional nitrogen fertilizer. With current nitrogen prices around 60 cents per pound, eliminating the need for commercial fertilizer can save between $40 and $60 per acre per year. Also, the legumes will improve the quality of forage and hay, and help fill in the “summer slump” in growth of most cool-season grasses. Frost-seeding is a low-cost option for adding clover species to an existing pasture during late winter or early spring. Planting with a no-till drill after the soil thaws adds some cost but generally results in better, more uniform germination. Alfalfa should be planted with a drill rather than frost-seeded because it germinates at higher soil temperatures compared with clover.