In addition to nitrogen, phosphoric acid, and potash, manure contains considerable calcium and smaller amounts of minor elements. The amounts vary with kind of animal, composition of feed, age of animal, milk production, and individuality of the animal. For example, about two-thirds of the nitrogen and one-half of the phosphorus carried in the ration of a well-fed, heavy-producing dairy cow is excreted in manure. A well-fed two-year-old steer excretes almost 90 per cent of the nitrogen and phosphorus consumed. The organic matter and bacteria contained contribute benefits beyond those of the plant food.