44 IOWA ACADEMY OF SCIENCE Vol. XXVI, 1919 



discover ways and means by which waste or unintelligent use 

 may be reduced to a minimum. In other words practice economy 

 in the use of our most vitally important natural resource. 



Up to the present time there is no evidence to support the view 

 that the country is undergoing a change toward aridity, that rain- 

 fall is gradually becoming less. Neither do the facts show that 

 cultivation increases the rainfall and that deforestation reduces 

 it. According to McGee': "The chief cause of lowering of the 

 sub-soil water — the waste of storm and thaw waters through 

 surface run-oflf — is remediable, and with the advance and diffu- 

 sion of intelligence is bound to be remedied." 



This waste is responsible for the mechanical and chemical soil 

 losses, destructive floods and resultant property damage ; the 

 silting up of streams, destroying their navigability, and the con- 

 tamination of water supply. Additional water losses and conse- 

 quent lowering of the ground water come through the cultivation 

 of the land ; drainage, industrial operations, especially mining, 

 and water consumed by man and domestic animals ; the latter 

 being almost negligible. 



The really great loss through storm and thaw can be effec- 

 tively reduced through proper drainage and cultivation. Tile 

 drainage lowers the ground water but reduces the direct run-off 

 and is especially effective in reducing the wasting of the land. 

 Open ditches lower the subsoil water and increase the run-off, 

 in addition to interfering with general farming operations. The 

 ditch always destroys the land for agricultural purposes and the 

 spoil banks too frequently are worse than useless as they become 

 the breeding grounds for all manner of foul weeds. In general 

 from two to eight acres of land per mile are rendered non-pro- 

 ductive. Tiling equalizes the run-off while the open ditch in- 

 creases the inequality between flood and low water. 



In north central Iowa the numerous ponds and lakelets origi- 

 nally present were Nature's method of conserving the ground 

 water level, stabilizing stream flow and reducing soil waste. The 

 wholesale destruction of these natural devices through the open 

 ditch, or tile drains with catch basins, has more or less completely 

 removed these natural safeguards. 



In the great mountain regions of the United States the Federal 

 Government has taken over large tracts of land as forest reserves 

 on the theory that it was necessary to exercise protective control 



'Bui. No. 92, pp. 178 et seq. Bureau of Soils. 



