It is also a good fact that as an average of sixty years the yield of barley was increased by 21.6 bushels an acre by nitrogen; that nitrogen increased the yield of hay on permanent meadow land at Rothamsted by 1-1/2 tons an acre as a fifty-year average; and that nitrogen increased the average yield of potatoes by 88 bushels as an average of twenty-six years; while the average of the unfertilized land was only 51 bushels an acre, these increases in barley, bay, and potatoes being obtained over and above the yields where minerals alone were used.

Where Is Nitrogen?

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: