10 FUNDAMENTALS OF AGRICULTURE. 



Certain bacteria living in the soil penetrate the root 

 hairs of plants belonging to the legume or pea family, 

 causing the development of small nodules or tubercles 

 within which they develop in great abundance, and 

 from which they derive a part of their nourishment. 

 The nitrogen which they need, however, to produce 

 protoplasm is absorbed from the air of the soil, and 

 then the plant absorbing the material set free in the 

 decomposition of these bacteria in the tubercles secure 

 their supply of nitrogen and build it up into their tissue. 

 It is, therefore, possible for plants of this family, when 

 these bacteria are present to grow well on soil not 

 supplied with organic matter, provided, of course, they 

 have the necessary supply of potash, phosphate, lime, 

 magnesia, and other essential elements. 



Roots of Legumes Leave Nitrogen in the Soil. 

 Moreover these plants not only secure the nitrogen 

 in this way which is left in their seed of the aerial part 

 of the plant, but a good deal secured in this way is 

 left in the roots of the plants and so when this sod of 

 clover, cow peas, or soy beans or other such crop is 

 plowed, and later planted to cotton, corn, or other 

 crop, not able to secure its nitrogen in this way, it is 

 supplied with nitrogen coming from the decomposition 

 of the roots of the legume plants. The growing of a 

 good crop of cow peas or soy beans will in this way 

 usually leave enough nitrogen in the soil for a good 

 crop of cotton or corn, and therefore the rotation of a 

 legume plant with other crops is one of the most im- 

 portant methods to be used" by the farmer in main- 

 taining fertility. 



Legumes do not Interfere with the Growing of 

 Other Crops. It is often possible to sow some legume, 

 such as crimson clover, cow peas, or soy beans between 

 the rows of cultivated plants at the time of their last 

 cultivation, which by growing during the fall and fol- 

 lowing spring, add greatly to the nitrogen of the soil 

 without the necessity of giving up the ground an en- 

 tire year for this purpose. 



