280 GREEN MANURING. 



in autumn, rye is sown to plow under for a late spring or summer 

 crop. This grass grows well in cool weather, but does not return 

 so much to the soil as red clover or some other legume. 



In green manuring the whole vegetable growth is returned to 

 the soil, and in a condition to insure rapid decomposition. In 

 no other way can a soil in poor condition be brought into good 

 condition so rapidly and by so little expenditure of money. By 

 its skillful use the light and shifting sands of Belgium have been 

 made the most fruitful fields of Europe. 



Many are prejudiced against green manuring, believing that 

 the process gives back to the soil only what it has taken from the 

 soil. There is in most soils a large store of reserve material for 

 plant food, but in the insoluble and inactive form. Certain 

 plants have a singular power of corroding these insoluble min- 

 erals and bringing them into soluble condition, using them to 

 build up their own tissues. When such plant is plowed under 

 the soil it may give back to the soil only what it took from the 

 soil, yet add greatly to its fertility because it has transferred such 

 materials from the retired to the active list. But it is not true 

 that plants give back to the soil only what they have taken from 

 the soil. All plants take carbon from the air, and green manur- 

 ing is the easiest way to increase the store of humus in the soil. 

 Certain kinds of jilants have singular power of accumulating 

 combined nitrogen, and when these plants, rich in nitrogen, are 

 plowed under the soil, they give to the soil in active form some- 

 thing which they did not take from the soil in this form. 

 Nitrogen is the most precious and costly element of vegetable 

 growth. 



In the Northern States red clover heads the list, and is the 

 red-plumed commander-in-chief of the manurial forces. Where 

 the cow pea thrives, it also acts much like red clover when 

 plowed under the soil. 



