Farmyard and Green-Manures 129 



The nitrogen gatherers belong to the legume, or clover, 

 family, and do not depend solely upon soil sources, but 

 rather gather the element from outside, and thus do not 

 reduce the content of soil nitrogen. Distinguishing 

 features of the plants of this order are that the seeds are 

 formed in a pod or legume, and that they have the power 

 of acquiring at least a large part of their nitrogen from the 

 air. These, when plowed down as green-manures, add 

 directly to the crop-producing capacity of soils poor in 

 nitrogen, because increasing their content of this element. 

 In order that the plant may obtain its nitrogen from the 

 air, however, the soil must originally contain, or must be 

 inoculated with, a specific germ, the presence of which is 

 manifested by the growth of nodules upon the roots, 

 through which it is believed the nitrogen is obtained. 

 Most well-tilled soils contain these germs in abundance. 



The "nitrogen consumers" are those which can obtain 

 their nitrogen only from the soil ; these consume the nitro- 

 gen existing there, and their growth and removal exhausts 

 the soil of this element. 



Notwithstanding the very great advantages of the 

 "nitrogen gatherers" as green-manures, they cannot be 

 solely depended upon to increase the crop-producing 

 capacity of the soil. That is, soils that are very poor, 

 both in their content of nitrogen and of the essential 

 mineral elements, cannot be made very productive by the 

 sole use of green-manures. In fact, the green-manure 

 crops cannot be grown with advantage unless they are 

 supplied with an abundance of the mineral elements, 

 phosphoric acid and potash ; hence helpful green-manuring 

 for such soils must be preceded and accompanied by liberal 

 fertilization with the minerals, phosphoric acid, potash 

 and lime. With these added in sufficient amounts, and 



