Extremely high nitrate content in forages may present potential horse health problems. As a guide, 60 pounds or less of nitrogen applied per acre of pasture is considered safe. Sixty to 100 pounds of nitrogen applied per acre is marginal and may sometimes cause potential problems. If 100 pounds of nitrogen per acre is applied, horses should be kept from grazing until after a rain. Other precautions in pasture fertilization are:
1. Do not spill fertilizer in horse areas. If you do, thoroughly clean it up and till if necessary.
2. Do liming in the absence of horses. Keep horses off limed pasture until after a rain. Lime dust inhalation may cause respiratory problems.
3. If fertilizer adheres to wet forage at application time, horses should be withheld until after a rain. Avoid fertilizer application to wet foliage.