CHAPTER VI 



MANURING AND FERTILIZING 



COVER CROPS may be said to be supple- 

 mentary to tillage. In the previous 

 chapter this function has been discussed. 

 It now remains to point out another Important 

 function — that of a green manure crop add- 

 ing humus and plant food to the soil. Not only 

 do some cover crops add plant food and all 

 humus to the soil, but they tend to conserve 

 these by preventing leaching, especially of ni- 

 trates, and they help to render plant food more 

 available by reworking It and leaving It In a 

 form more available for the tree. They some- 

 times act as a protection against winter injury 

 by holding snow and by their own bulk. They 

 also help to dry out the soil in spring, thus 

 making the land tillable earlier. 



There are two great classes of cover or green 

 manure crops, leguminous and non-leguminous. 

 A non-leguminous crop merely adds humus and 



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