Distribution of Alkali in Soil 283 



concentration had been prevented no serious harm 

 could have resulted. So, too, if the salts have been 

 gathered into a thin layer near the surface, heavy 

 rains or an application of water by irrigation may 

 move them at once bodily and nearly completely to a 

 depth of 1, 2 or 3 feet, varying with the amount of 

 water applied, the capacity of the soil to store water, 

 and the amount of water it contained previous to the 

 application. Under these circumstances, it is plain 

 that fields afflicted with alkalies may exhibit at one 

 time the most intense symptoms of poisoning and at 

 another be entirely free from them, so far as revealed 

 by a crop upon the ground. 



In examining soils for alkalies, it is a matter of 

 the utmost importance to recognize that the distribu- 

 tion of them is extremely liable to be capricious, and 

 that it is easy to overlook their presence by stopping 

 the sampling of the soil just short of the level at 

 which all of the alkalies had chanced to be concen- 

 trated ; or, again, by taking a sample of the 1st, 2d 

 and 4th feet, or of the 1st, 3d and 4th feet when, ow- 

 ing to the capricious distribution, all of the salts had 

 been collected in the 2d or 3d foot, and thus were 

 overlooked because it may have been thought not 

 worth while to make a complete section of the soil 

 in question. 



CONDITIONS WHICH MODIFY THE DISTRIBUTION 

 OF ALKALIES IN SOIL 



If the surface of the ground is kept naked and 

 compact, so that the rate of evaporation may be 



