The only remaining element of the soil is phosphorus. This element was discovered in 1607, the year of the first English settlement at Jamestown and was first noticed because of its property of giving off light from itself. The name which was given it means light-bearer. It was at first thought to be the source of all power, to heal all diseases, and to turn the common minerals into gold. Although we have long ago learned that these ideas are absurd, yet we have also learned that its real value to man is far greater than was even dreamed of then. It is the most important element in every living thing, for no cell, however small, in either animal or vegetable organisms can grow or even live without phosphorus. It is found in the green of the leaves, and helps to make the starch. It enters largely into the grain and seeds of plants, and is necessary for their germination, or sprouting, as well as their growth. Three-fourths of all the phosphorus in a crop of cereals is in the grains, giving them size and weight. It will thus be seen how necessary it is that the soil which feeds our plants, which in turn become the food of animals and of man, should contain a sufficient amount of phosphorus. Phosphorus is taken from the soil in large quantities by every kind of crop. In parts of Wisconsin which have been farmed a little more than fifty years without fertilizing, it is found that about one-third of the phosphorus has been taken out of the soil, which would mean that in one hundred and fifty years, or a hundred years from now, the soil would be incapable of producing any living thing, and long before that time the crops would not pay for the labor of producing them. Almost every acre of land that has been farmed for ten years without fertilization is deficient in phosphorus, that is, so much has been used that the soil can no longer produce at its former rate. It may be asked, if this be true, why the soil of America, which before it was cultivated had borne rich forests and fields of waving grass, has not become exhausted long ago. We must remember that nature always adjusts itself; that, in the wild state, all plants decay where they grow, and the same elements are returned again to the soil. But when the entire product of vast areas is removed year after year, the soil has nothing except the slow rock-decay with which to renew itself. In tropical regions it is not necessary to feed domestic animals at any season of the year, but in those countries where the natural food can be found only during a part of the year, the need of artificial feeding is seen at once, and it becomes a part of the regular expense of farming. It would be considered the height of folly for a man to allow his valuable animals to starve to death because of the expense of feeding them, but few people recognize the fact, which is also true, that it is equally bad business policy to allow the valuable crops of wheat, oats, and corn to starve for want of plant food.