Increasing the fertility of the soil upon which it gro-ws. This fact has 

 long l)een accepted by farmers and students of agriculture, but until 

 recent discoveries in Germany and America it was believed that the 

 chief function of these plants was to pumj) up nitrogen from the sub- 

 soil reservoir to the surface by means of their long roots for the use 

 and benefit of succeeding crops. 



But experiments in the field and laboratory for the purpose of deter- 

 mining the causes of natural phenomena have taken the place of class- 

 room philosophy and speculative reasoning. . Within the last twenty 

 years scientific workers have discovered that minute micro-organisms, 

 or bacteria, which live within the tissues of the roots of leguminous 

 plants take up free nitrogen froui the gases in the soil, just as the 

 higher i:)lants and animals utilize the oxygen of the air. This nitrogen 

 enters into combination to form nitric acid, Avhicli unites with the min- 

 eral elements of the soil to form nitrates, a kind of plant food exceed- 

 ingly vahmble to the growing crop. Nitrogen, when in combination 

 with other elements, is an indispensable form of i^lant and animal 

 food, but the free element can not be utilized, uncombined, by any of 

 the higher organisms. Small amounts of nitrous acid are formed 

 as a result of lightning discharges and are washed out of the air by the 

 rains, to be in part absorbed by the soil, and in part carried by rivers 

 and drainage waters into the sea. Free nitrogen exists onl}^ in the 

 air and in the gases of the soil, but as ammonia, nitrous and nitric 

 acid, nitrites and nitrates, it is present in varying quantities in 

 the soil, the unbroken rocks, and the waters of continents and 

 oceans. 



The most available j^urchasable nitrogen is obtained either as salt- 

 peter or nitrate of soda from the extensive deposits in the Peruvian 

 deserts, or from some form of animal wastes, such as freshly ground 

 bone, dried blood, guano, tankage, and fish scrap, and from cotton-seed 

 meal and other like bj'-products of the oil mills. These fertilizers are 

 all exf)ensive, so much so that they can be i)rofitably employed b\' the 

 farmer only in intensive farming with specialized crops. The gain in 

 yield with low-jDriced crops, such as corn, cotton, tobacco, cowpeas, 

 and the grasses, using high-grade and costly fertilizers, is not com- 

 mensurate with the additional expense. But everj^ farmer, rich and 

 poor, has over three thousand tons of atmospheric nitrogen resting on 

 every acre of his farm, a certain quantity of which can be transformed 

 into available plant food every time that he grows a crop of cowpeas, 

 red clover, or alfalfa. 



There are a great many acres of farming hind in the South in need 

 of renovation. The red uplands and yellow-clay soils were undoubtedly 

 less fertile originally than the alluvial and black prairie soils, and the 

 methods of cultivation which formerly prevailed have still further 

 diminished their productiveness. In the days when every plantation 



