CLOVER CULTURE. 14. 



in 1884, and in detail in the American Chemical Journal, 

 volume 6, page 365 (February, 1885). The question foi 

 study in the first series was : Will peas grown under normal 

 conditions acquire any considerable amount of nitrogen free 

 or combined from the air? When the subject was resumed 

 in 1885, it was to obtain an answer to the two following ques- 

 tions : What effect has the addition of soil infusions on the 

 formation of root tubercles, and is there any definite relation 

 between the quantity and the number of root tubercles and 

 the quantity of atmospheric nitrogen obtained by the plant? 

 We cannot follow the experiments in detail. Suffice it to say 

 that they were conducted with sea sand, thoroughly washed 

 and boiled and the methods adopted were almost identical 

 with those adopted by the German experimenters. They 

 covered, as in the German experiments, the cereals as 

 well as the legumes, and the conclusions to which Prof. 

 Atwater arrived were, that the cereals could not obtain nitro- 

 gen from the atmosphere, while the legumes could and did. 

 His conclusions may be summed up as follows : That the 

 leguminous plants in general are able to secure large quan- 

 tities of nitrogen from the air during their period of growth ; 

 that there is scarcely room to doubt thai t^e free nitrogen of 

 the air is thus acquired by the plant ; that without root tuber- 

 cles there was in no case any large gain of nitrogen, and that 

 with them there was uniformly more or less gain, and that 

 the greater the abundance and number of root tubercles 

 the larger and more vigorous the plants and the greater the 

 amount of atmospheric nitrogen acquired. Still further, 

 that the connection between the root tubercles and the 

 acquisition of nitrogen is: clearly demonstrated, but that the 

 relation of the bacteria to the root tubercles and to the 

 acquisition of nitrogen, and in general how the nitrogen is 

 obtained, are questions yet to be solved. In conclusion Prof. 

 Atwater says : 



This subject has a wider significance than what has been said above 

 implies. The future welfare of our race, material, intellectual and moral, 

 depends upon the food supply, or, in other words, upon the product of the 

 soil. This in turn reduces itself essentially to a question of phosphoric 

 acid, potash and nitrogen. Enough of the first two for an indefinite time 

 to come is assured in the deposits of phosphates and potash salts already 

 discovered, but the probability of a sufficient supply of nitrogen has been 

 Questioned. This costliest of the fertilizing elements escapes from our 

 soils into the air and into the sea, and is taken away by crops, and not 

 completely returned. Artificial fertilizers promise to meet but a small 

 fraction of the coming demand. If, as has been urged, the exhaustless 

 stores of the atmosphere are not available to plants, the outlook is dark 

 enough. But if the farmer may use his crops to gather it, without money 

 and without price, we may dismiss our solicitude. With the assurance 



