During the past ten years our population has increased at the rate of two per cent per annum, while our crop production has increased only one-half as fast. In six years the number of beef cattle produced in this country has fallen off about five per cent per annum. The cost of foodstuffs recently has been increasing at the rate of five per cent per annum. The hardships experienced by wage-earners, particularly in the United States, have been very great in view of the fact that the cost of food increased more rapidly than wages--at a rate approximately double. The same tendencies apply with some modifications to the clothing of mankind. These facts point to the necessity of increasing the yields both of the food crops and the crops that are used in the making of clothing. [Illustration: WRAPPER LEAF TOBACCO CROP FERTILIZED WITH CYANAMID MIXTURES. GROWN IN HATFIELD, MASS.] The problem of decreasing the cost of living has been given far more attention abroad than it has in this country, owing to the much greater density of population in the principal nations of Europe. For a long time it has been known that plants require food the same as animals and human beings. Without food plants cannot live and grow, and just to the extent that plant food is present in the soil, to that extent will a crop be produced. The most important of plant foods is nitrogen. While the earth is literally bathed in nitrogen, this element is found to only a very slight degree in the soil. That is to say, the air which we breathe and in which we move is four-fifths nitrogen, yet in the richest soil there is seldom more than one-tenth or two-tenths of one per cent of nitrogen. Put on a wheat crop one pound of nitrogen and you can take off twenty pounds more wheat and forty pounds more straw than you could if you failed to make this application. One pound of nitrogen properly applied to a cornfield will add thirty-five pounds to the crop; one pound of nitrogen will produce one hundred pounds of increase in the potato crop; one pound of nitrogen will produce five pounds of cotton, without any extra labor being devoted to the production of the crop. Nitrogen is the heart and soul of the problem of growing more crops and cheaper crops. Take any nation that produces large crop yields per acre and you will find that the nation that uses the most nitrogen per acre grows the largest crops. For years the nations of Europe have been depending to a great extent upon supplies of nitrate of soda obtained from Chile, in South America. Germany alone imported nearly a million tons of this salt annually before the war. Then, too, the by-products of many industries furnish a quantity of nitrogen, but all this, it was realized, furnished but a small part of what was required to combat the constantly rising cost of producing food.