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SOIL PHYSICS AND MANAGEMENT 



The cropping to which the soil has been subjected determines 

 to a large extent the plant-food content. Every crop removed from 

 the land takes away a certain amount of food, thus slowly reducing 

 the supply. 



The next table gives the amount of plant food in soils from 

 various countries. 



Total Plant Food in Some Residual Soils.* Pounds in Two Million Pounds 



of Soil 



* Compiled from various sources. 



Fertility in Russian Steppe or Tchernozem Soils. 1 Pounds in Two Million 



Pounds of Soil 



Plant Food in Missouri Soils. 2 Pounds in Two Million Pounds of Soil 



