CHAPTER XXV 

 FARM DRAINAGE 



SOME farm lands contain so much water that the 

 conditions of fertility are interfered with and there- 

 fore the crop producing power of these lands is 

 lowered. 



HOW SURPLUS WATER AFFECTS FERTILITY 



This surplus water diminishes fertility by reduc- 

 ing the area of film water in the soil. 

 It checks soil ventilation. 

 It tends to keep the soil cold. 

 It dilutes plant food in the soil. 

 It interferes with proper tillage. 



INDICATIONS OF A NEED OF DRAINAGE 



The above-mentioned state of affairs occurs some- 

 times in fields at the foot of hills, or on sloping up- 

 lands which receive spring water or seepage water 

 from higher lands. Some fields are underlaid by a 

 close, compact subsoil which so checks percolation 

 that the surface soil is too wet for tillage operations 

 the greater part of the year. In such cases : 



A need of drainage is generally indicated by the 



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