How Alkalies Accumulate in Soil 273 



more rapid formation of all the true alkalies of arid 

 climates; for fundamentally similar rock ingredients 

 are subjected to identical weathering processes, but of 

 a more intense nature, because the rainfall is greater. 

 If, therefore, there occur conditions favorable to the 

 accumulation of the soluble salts formed at and near 

 the surface of the soil, these should be expected to 

 show as alkalies. 



Most of the marsh lands of the world, excepting 

 those under the influence of tide waters, owe their 

 wet character to the underflow of ground-water which 

 has percolated into the adjacent higher lands, and 

 which rises to or near the surface wherever this is 

 sufficiently low to permit of it doing so. When such 

 lands are drained, the rate of surface evaporation and 

 the rise of capillary water from below may exceed 

 the annual rainfall, and thus lead to an accumulation 

 at the surface of salts of 'such intensity and character 

 as to interfere with the normal growth of plants. 



It must be kept in mind that where the ground -water 

 level is near the surface, the rate of capillary rise may 

 many times exceed what it could be under other con- 

 ditions, and since the rate of evaporation is most 

 rapid where the surface soil is wettest, the conditions 

 are extremely favorable for the accumulation of solu- 

 ble salts at the surface of marsh lands in humid 

 climates after they have been drained. The waters 

 leaching through the more open, higher lands become 

 charged with salts, and as these waters come again 

 near the surface under the low areas they are raised 

 by capillarity and evaporated, leaving the salts which 



