CHAPTER III 



SOILS 



Constituents of soil. 



Formation of soil. 



Classification of soil according to mode of formation. 



Residual, cumulose, colluvial, alluvial, marine, lacustrine, 



glacial, seolian. 

 Classification of soil according to texture. 



Clay, silty, sandy, gravelly, stony, loam. 

 Classification of soil according to rainfall. 



Humid, arid, semi-arid, semi-humid. 

 Heavy and light soils. 

 Structure of soil. 



Separate-grained, puddled, granular. 



Conditions affecting soil structure. 

 Functions of water in soil. 

 Forms of water in soil. 



Hygroscopic, capillary, gravitational. 

 Control of soil-water by cropping methods. 



Reducing run-off losses. 



Reducing percolation losses. 



Reducing evaporation losses. 



Improving soil structure to increase soil-water. 

 Irrigation. 



Overhead irrigation. 



Sub-irrigation. 



Flooding. 



Furrow irrigation. 

 Soil drainage. 



Open-ditch drainage. 



Underdrainage. 

 Air in soil. 

 Bacteria in soil. 



No people can be permanently prosperous and progressive 

 unless it thoughtfully cares for its soil. It is out of the soil 

 that the agricultural products come, for even the fish that the 



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