CHAPTER IV. 



THE SILAGE SYSTEM HELPS MAINTAIN 

 SOIL FERTILITY. 



When the cattle feeders of this country once thoroughly 

 realize that they can profitably feed and raise stock by 

 means of the silage system, the great problem of maintain- 

 ing and increasing soil fertility will very largely solve 

 itself, and exhausted soils will recuperate of their own 

 accord. 



This statement is based on certain fundamental facts, 

 which Farmer's Bulletin No. 180 covers briefly as follows: 



"When subjected to proper chemical tests or processes 

 every substance found on our globe, no matter whether it 

 belongs to the mineral, vegetable or animal kingdom, 

 may be reduced to single elements, of which we now 

 know over seventy. Many of these elements occur but 

 rarely, and others are present everywhere in abundance. 

 United mostly in comparatively simple combinations of 

 less than half a dozen each, these elements make up 

 rocks, soils, crops, animals, the atmosphere, water, etc. 

 The crops in their growth take some of the elements from 

 the soil in which they grow and others from the air. 

 Many elements are of no value to crops; a few, viz., 13 

 or 14, are, on the other hand, absolutely necessary to the 

 growth of plants; if one or more of these essential ele- 

 ments are lacking or present in insufficient quantities in 

 the soil, the plant cannot make a normal growth, no matter 

 in what quantities the others may occur, and the yields 

 obtained will be decreased as a result." 



The problem of the conservation of soil fertility is 

 therefore largely one of maintaining a readily available 

 supply of the essential plant elements in the soil. Most of 

 these elements occur in abundance in all soils, and there 

 are really only about three of them that the farmer need 

 seriously consider nitrogen, phosphorous and potash. 



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