As a rule the so-called "practical" farmer is a theorist. He first believes that the virgin soil is inexhaustible, even though cropped continuously. Later he clings to the popular theory that the rotation of crops will maintain the productive capacity of the land; and it is safe to say that a large majority of the farmers of the United States gladly hold to the erroneous theory that clover grown once every three to five years will increase and permanently maintain the fertility of the soil. The fact that clover was grown for generations on the lands of the older Eastern states until the clover crop itself finally failed on millions of acres now agriculturally abandoned is overlooked or forgotten by present-day farmers, especially by the descendants of those who have gone West and settled on new, rich lands. Six Facts and a Question The following six facts will furnish a comprehensive basis for the solution of the nitrogen problem in practical general agriculture: (1) To produce 100 pounds of grain requires about 3 pounds of nitrogen, of which 2 pounds are deposited in the grain itself and 1 pound in the straw or stalks. (2) In live-stock farming one-fourth of the nitrogen in the food consumed is retained in the animal products--meat, milk, wool, and so on--and three-fourths may be returned to the land in the excrements if saved without loss. (3) When grown on soils of normal productive capacity legumes secure about two-thirds of their total nitrogen from the air and one-third from the soil. (4) Clover and other biennial or perennial legumes have about two-thirds of their total nitrogen in the tops and one-third in the roots, while the roots of cowpeas and other annual legumes contain only about one-tenth of their total nitrogen. (5) Hay made from our common legumes contains about 40 pounds of nitrogen per ton. (6) Average farm manure contains 16 pounds of nitrogen per ton. Question: How many tons of average farm manure must be applied to a 40-acre field in order to provide as much nitrogen as would be added to the soil by plowing under 2-1/2 tons of clover per acre? Answer: 400 tons. Either method will furnish about as much nitrogen as would be taken from the soil by a 50-bushel crop of wheat, a 75-bushel crop of corn or a 100-bushel crop of oats per acre. The decision by the individual between live-stock farming and grain farming should be based upon preference and profit rather than upon the erroneous teaching that farm manure is either essential or sufficient for the maintenance of soil fertility in this country. Bread is the staff of life, and many must sell grain. I do not advise all grain farmers to become live-stock farmers; but I do advise both grain farmers and live-stock farmers to enrich their soils by practical, profitable and permanent methods. Both classes of farmers may secure new nitrogen--that is, they can positively increase their nitrogen supply by sufficient use of legume crops. How to Supply Nitrogen