IMPROVEMENT OF ALKALINE SOILS. 181 



for any use to the stock-raiser or farmer. These lands 

 may easily be reclaimed by irrigation. Copious watering, 

 continuously applied, will wash out the soluble alkali from 

 the subsoil and render them arable. But the watering 

 must be long continued, and at a season when evaporation 

 is the least active. It is the evaporation of moisture from 

 such soils, that brings to the surface the alkaline matter, 

 where it effloresces and makes them appear as if covered 

 with newly fallen snow or hoar frost. All this injurious 

 matter, chiefly consisting of soda salts, may be removed 

 through the subsoil by the continued action of irrigation, 

 and washed into the rivers and the sea. The water 

 charged with these salts, which in excess are destructive, 

 but in moderate supply are helpful, may in fact be used 

 over again on its passage down the rivers after it has 

 emerged beneath the surface in hundreds of springs, 

 upon new fields, which actually need this alkaline matter 

 to make them fruitful. 



Another highly important consideration presents itself. 

 It is found that after a few years of irrigation, the soil 

 requires the artificial application of less water ; that the 

 atmosphere becomes more highly charged with moisture, 

 and that the evaporation from the surface becomes, in 

 consequence, less and less as years pass ; that the rainfall 

 is increased, and that the supply of water becomes rela- 

 tively more abundant, as the land needs less of it, and 

 thus the area that may be irrigated, gradually increases. 

 The low lands are also moistened by the surplus from the 

 bench lands which percolates through them ; the soil be- 

 comes charged with vegetable matter, and more retentive 

 of water, and these effects react upon the climate. 



These effects have been more particularly noted in Utah, 

 where irrigation has been longest in use, and where the 

 growth of trees has been comparatively extensive. Al- 

 ready the increase in the rainfall has become noticeable, 

 and the level of Great Salt Lake has risen several feet, 



