222 BOARD OF AGRICULTURE. [Jan., 



A part of this difiference between legumes and other kinds 

 of crops may be explained by their deeper rooting ; a part also 

 perhaps by their stronger feeding capacity — their ability to 

 assimilate forms of nitrogen from the soil which cereals can- 

 not assimilate — to eat, let us say, what cereals cannot eat; and 

 partly (and to my mind only partly) this nitrogen-gathering 

 quality is to be explained by the action of those bacteria which 

 live on the roots and in connection with the well-known 

 " nodules " of the roots. It has been fully proved that alfalfa 

 plants having these nodules with living bacteria, are able, in 

 ways not fully understood, to get hold of the free nitrogen of the 

 air in the soil and combine it in vegetable forms. This, other 

 plants than legumes, with few exceptions, and as far as we 

 now know, cannot do. This gives to alfalfa and other legumes 

 their greatest agricultural value. .They enrich the crop and^ 

 through the roots, stubble and crop residues, the soil itself with 

 nitrogen, that most expensive element of plant food. This 

 fact of the enrichment of the soil by legumes was well known 

 a good while ago, and the practice of growing pulse alter- 

 nately with a grain crop is immemorial in India. Such parts 

 of the explanation as we now have it is quite modern. 



I believe that Professor Atwater and Dr. C. D. Woods at 

 Middletown were the first to give an absolute proof of the as- 

 similation of free nitrogen by legumes under conditions which 

 were beyond criticism, and European investigators chiefly have 

 taught us what we know of the extent and the method of this 

 assimilation. 



It is not the only way in which soils gather free nitrogen. 

 It is certain that other microbes, low forms of vegetable life^ 

 which are not connected with legimies, also gather it. A soil 

 containing humus and not acid, under favorable conditions^ 

 wnll of itself gather a certain amount of nitrogen. What con- 

 ditions favor this and how much nitrogen may be gathered by 

 this means remains to be learned, and to my mind this is one 

 of the most important questions regarding the maintenance of 

 soil fertility which is waiting for solution. 



But certainly the supply of free nitrogen which legumes 

 furnish seems at present to be far greater and more rapid than 

 that from other sources. 



The raising of legumes is and has long been known to be 

 a "way of restoring exhausted soils, by increasing the amount 



