If the soil is to acidic, you may not be able to grow the plants you would like to grow. Lime can be added to the soil to neutralize it. Phosphorous and potassium, along with nitrogen are commonly required for pasture fertilization. Regular weeding of the pasture is also important. Toxic weeds may become established in a pasture very quickly, causing horses to become seriously ill.
Poisonous plants have a tendency to grow along fence lines as well as around ponds and lakes.
Knowing which poisonous plants grow in your area is very important. If pastures are not reseeded, weeds may dominate the field, the quality of forage may be low, and the soil will become depleted of essential minerals. By reseeding the pasture, you are allowing the plants to remain evenly mixed. If pastures are never reseeded, nutritious, beneficial plants may become restricted to only certain parts of the field. Ideally the pasture should bot be used for one entire year after two years of grazing, so that the minerals are not depleted to rapidly.