Animal poop contains nitrogen, the key nutrient that soils need to grow plants. We shovel the sheep manure up and spread it on a field nearby in areas that need the extra fertilizer.
Many farmers use the manure from their cattle or hog facilities to spread on their fields, yet it is not enough for all of their acres. Unfortunately, farmers need to purchase N (nitrogen), P (phosphorus) and K (potassium) along with lime, sulfur and sometimes zinc to help the future plants grow. Fertilizer costs rise as market commodity prices rise, making it very expensive. You have to be careful that you manage your input relative to your output.