CHAPTER II. 

 Drainage. 



MODIFYING THE SOIL. 



Soil can be modified in some of the following ways : 



1. Drainage. 



2. Plowing and cultivation. 



3. Humus in the soil. 



4. Application of chemical fertilizers. 



5. Cropping. 



6. Rotation of crops. 



7. Inoculation. 



Drainage is one of the great world problems. 



The drainage investigations conducted by the United States 

 Government furnishes information that ought to play an im- 

 portant part in the development and conservation of our natural 

 resources. 



There are in the United States about 79,000,000 acres of 

 land exclusive of tidal marshes that can not be profitably cul- 

 tivated on account of too much moisture. There are over 60 

 million acres of swamp lands in the United States east of the 

 looth meridian. 



It has been estimated by experts that the following number 

 of acres can be drained with profit as follows : 



52 million acres that are continually wet. 



7 million acres of wet grazing land. 

 14 million acres that periodically overflow. 



5 million acres that are periodically swampy. 



PROBLEMS. 



1. Assuming that 50 million acres of this land is practically worth- 

 less, and that drainage would make this land worth $100 per acre, what 

 would be the net profit measured by land values if the cost of Drainage 

 were on an average $25 per acre? 



_ ) . It has been estimated that the increase of annual income from 

 2 (17) 



