RECLAIMING LOST NITROGEN 137 



quickly: they act with munificence: they act constantly. 

 It has been known for some time that the legumes were 

 not soil depleters, as wheat or corn or cotton as every 

 other form of plant : they always helped the plant. In 

 what manner no one knew. But this was observed : 

 when corn or wheat or other cereal followed clover or 

 other legume, a much greater yield was secured than on 

 similar land, similarly treated, but without the legume 

 crop. The evidence was so conclusive that long ago clo- 

 ver and peas were hailed as soil improvers and land build- 

 ers. Of course, their goodness was never associated with 

 bacteria. While the peculiar nodules were observed on 

 the roots of these special plants, they were believed to 

 be disease evidences rather than homes of friendly-work- 

 ing bacteria. 



It has been noticed in a previous chapter that Lawes 

 and Gilbert in England made some extensive experiments 

 with the legumes and that their observation showed noth- 

 ing favorable from their use. You wonder why? Here 

 is the explanation : they never had the aid of the bacteria, 

 the good fairies of this work. These investigators were 

 so careful that no error should creep into their work, they 

 either never got soil possessing bacteria, or because of 

 sterilization or of the chemicals used, the development 

 and, hence, the good work of these nitrogen gatherers 

 was prevented. 



Root tubercles: the place of nitrogen manufacture. 

 Have you ever noticed the swellings that appear on the 

 roots of such garden plants as peas and beans or on any 

 such field crops as clover and alfalfa? No? Well, they 

 certainly are there if your crops are growing abundantly 

 and vigorously. You will find roots of such crops often 

 largely covered with wart-like growths. These are the 

 homes of nitrogen-gathering bacteria. Some people call 



