gen?

If nitrogen has such enormous power to increase the yield of our
great staple farm crops then we may well inquire, Where is nitrogen,
and how can it be secured economically and utilized profitably in
practical agriculture?

The weight of the atmosphere is 15 pounds to the square inch. This
means that a column of air 1 inch square taken to the full height of
the terrestrial atmosphere weighs 15 pounds. More than three fourths
of the air is nitrogen. Since there are 43,560 square feet in one
acre, it follows that the nitrogen in the air above each acre of the
earth's surface amounts to 70,000,000 pounds, or nearly 500,000
times the 150 pounds of nitrogen required for a hundred-bushel crop
of corn. The leaves of the corn plant are blown about by the wind
carrying 75-1/2 per cent of nitrogen, but cannot utilize an ounce of
this supply.

Many people know that clover and other legumes have power, through
the bacteria which inhabit their root tubercles, to feed upon the
inexhaustible supply of atmospheric nitrogen which freely enters the
pores of the soil; but who knows how much nitrogen is taken from the
air by a given crop of clover? Not one in a thousand can answer this
question; and meanwhile our continued agricultural and national
prosperity depends in large part upon the possibility of wide
dissemination and practical application of a quantitative knowledge
of the nitrogen problem.

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 pound