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.