HOW TO KEEP SOIL FERTILE 37 



rich in organic matter often cause grains to lodge, or "go 

 down," badly. This is due to too much ready nitrogen, 

 which causes a rank growth. Manure never injures corn 

 by causing too rank a growth; and grains, such as wheat or 

 oats, may follow the corn the next year with little danger 

 of lodging. Most soils contain so great a supply of potash 

 that it can hardly be exhausted. Nitrogen can be replaced 

 by growing legumes. (See Chapter 9.) The phosphorus 

 supply, which is most apt to give out in average soils, can 

 be added most economically by using raw rock phosphate. 

 One ton of the rock phosphate to an acre will supply all 

 the phosphorus that the crops will need for more than ten 

 years. 



QUESTIONS AND EXERCISES. 



1. What do we mean when we say that a soil is "poor"? 



2. What three substances are often lacking in soils? 



3. What substances are supplied to the soil by adding 

 wood ashes? Which one is easily removed from wood ashes 

 by leaching? 



4. Why do grain crops lodge on "rich" soils? 



5. Which farmer will have the "richer" soil, the one 

 who grows grain and hay and sells them off the farm, or 

 the one who feeds these crops to cattle and places all the 

 manure upon the soil? 



6. When manure is left exposed to rains, it loses about 

 one-half of its value in six months. On a farm in which 

 100 tons of manure is produced, what would be the conse- 

 quent loss, if the manure is worth $2.30 a ton? 



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