206 LAND DRAINAGE 



272. The meaning of the lowering of the ground 

 water-table in terms of rainfall. The greatest mean 

 lowering of ground water-table in any state recorded by 

 McGee is 4.663 feet for ten years, 1 or 5.5956 inches a year. 

 This 5.5956 inches of fall would be counteracted by from 

 1 inch 2 to 1 .4 inches of rain, depending upon the amount 

 of pore space existing in subsoil or rock. 



273. Intelligent soil management needed. It is very 

 likely that with the most intelligent soil management 

 during the transformation of great regions from a state 

 of nature to a state of domestication (agricultural pro- 

 duction), there would have been a readjustment of the 

 underlying ground water-table; but even with the non- 

 agricultural agencies at work (artesian well, mines, muni- 

 cipal wells and the like) the change would not have been 

 so great as it has been had more intelligent and less selfish 

 methods been employed in the agricultural practice of 

 these regions. 



274. The case not serious. But the case is not so 

 serious as many alarmists would have us believe. The 

 rainfall much exceeds that required for our present acreage 

 yields, doubled, trebled, and in some cases quadrupled, 

 in our humid areas. A better seasonal distribution of 

 precipitation, in some regions, could be desired; but 

 even unsatisfactory seasonal distribution may be partly, 

 if not wholly, counteracted by proper soil management 

 methods. The methods to be employed for this purpose 

 will undoubtedly go far toward arresting a further lower- 

 ing of the ground water-table, and should go far in restor- 

 ing it toward its original position. The run-off must be 

 decreased ; and cut-off must and can be increased. 



1 Bulletin 92, Bureau of Soils, p. 175. 



2 Waring, Draining for Profit, etc., p. 23. 



