If the grain farmer grows 40 bushels of wheat to the acre, clover
having been seeded on the same land in order to plow under the
equivalent of 1-1/2 tons of hay as green manure the following
spring, and follows this by a 60-bushel crop of corn and a 50-bushel
crop of oats, and this the fourth year by two crops of clover
aggregating 3 tons an acre, including 2 bushels of seed, he can thus
secure from the air about 180 pounds of nitrogen in the 4-1/2 tons
of clover. Moreover, if the first cutting of clover the fourth year
is left on the land and the threshed clover straw from the seed crop
and likewise all straw and stalks are returned to the soil, only 154
pounds of nitrogen an acre would leave the farm if the total grain
and clover seed were sold. With 80 cents a bushel for wheat, 50
cents for corn, 40 cents for oats and $8 for clover seed, the total
returns from the four acres would amount to $98.

On the other hand the live-stock farmer may grow two 60-bushel crops
of corn, followed by 50 bushels of oats and then 3 tons of clover
hay containing 120 pounds of new nitrogen. The four crops would
contain 350 pounds of nitrogen; and if the grain and hay and half
the corn-stalks are used for feed, with the straw and the remainder
of the stalks for bedding, it is likewise possible to replace the
230 pounds of nitrogen required for the grain crops, provided not
more than one-seventh of the manure is lost before being returned to
the land. The important weakness on the common live-stock farm lies
in the enormous waste of manure.

If 10 pounds of feed produce 1 pound increase in the live-weight of
the animals fed, and if they bring 6 cents a pound on the hoof, the
gross returns aggregate $107.50 from the four acres, barring losses
from accidents, animal diseases, and so on.