It is a fundamental principle of the best agriculture that every acre should be kept constantly at its highest productive capacity. In one sense the farm is a great machine for the production of food. All prosperity must originate on and emanate from the farm; the farmer is really the only original producer. The measure of the world’s material success must be the relative amount of the product of the farm. As lands decrease in fertility, the cost of living increases in direct proportion. As fertility decreases, land values decrease and rural population decreases. Already there are districts in America that are almost depopulated because of the barrenness of what was, but a short while ago, fertile land. The fundamental principle of maintaining fertility is to restore to the land annually those chemical elements taken from it by the crops grown. A prominent importer of horses relates that he was once entertained on a great horse farm in France, whose owner told him that much of the farm had been in cultivation for over eight hundred years and was, he believed, as productive now as ever in its history. Alfalfa ranks as the greatest fertilizing plant known to scientific agriculture. All cereal crops use large quantities of nitrogen. A field cropped for years in corn or wheat will come to have too little nitrogen for the production of a profitable crop. Alfalfa, as has already been stated, after the first few months of its life obtains its whole supply of nitrogen from the air; in fact, more than it really needs. As a soil improver it possesses at least five valuable properties: 1. It gathers nitrogen from the air for its own maintenance and a surplus that is constantly being added to the soil. 2. It is a deep feeder and its roots penetrate the earth to extraordinary depths, drawing toward the surface and utilizing moisture and valuable mineral elements that other crops would never reach, leaving the desirable elements there for future crops, of whatever kinds. 3. By capillarity, these roots and rootlets draw up moisture from below the surface until it modifies the very top soil, changing wonderfully the nature of the field. The analysis of a cubic foot of earth of a flourishing alfalfa field shows a marvelous change in moisture content since the sowing.