Soil Inoculation by Nitragin. 137 



leaves, and this they furnish, when plowed under, in an available 

 form as food for succeeding crops — a princely legacy to future 

 generations of plants. 



When the nodules and their inhabitants are not present, 

 clover, peas, etc., must, like all other plants, obtain all their 

 nitrogen from the soil. Further, it is to be noted that these 

 micro-organisms are not to be found in all soils. The question 

 of introducing them economically, therefore, naturally presents 

 itself as one worthy of research. 



The first experiments towards this end consisted in taking 

 soil from a field upon which a legume possessing an abundance 

 of nodules had been grown, and sowing it on the field to be im- 

 pregnated. This was practically soil inoculation and, though 

 the plan proved eminently satisfactory, the carrying out of it 

 was in many instances costly and cumbersome. Dr. Nobbe, of 

 Tharand, Saxony, was the one who first made this practical 

 application of Hellriegell's discovery. He, however, did not 

 stop there, but as we now have to chronicle, he prepared " pure 

 cultures" of these nitrogen-converdng organisms, by methods 

 well known to bacteriologists. These cultures or preparations 

 are now made on a commercial scale, so that a sufficient quantity 

 to inoculate an acre can be bought in Germany for $1.25. The 

 members of the leguminos^e have, it would appear, each their 

 own peculiar bacteria or micro-organisms; and it has been shown 

 that those influencing the assimilation of nitrogen in the clover 

 plant are of no value for the pea crop, and vice versa. Hence 

 the necessity for the preparation of cultures of clover bacteria' 

 pea bacteria, and so on ; and these must be used according to 

 the effect desired, or, in other words, according to the crop to be 

 sown. 



These cultures consist of " colonies " of these organisms 

 and the preparation has been named Nitragin. The practical 

 application of Nitragin has been tried in two ways : first, by 



