ABSORPTION OF SALTS BY SOILS. 130 



and possibly even chlorine to a small extent, and under some 

 conditions, are removed from solution or retained by soil sur- 

 faces. 



COMPARATIVE STUDY OF THE ABSORPTIVE POWER OF EIGHT 



SOIL TYPES. 



From the observations which have been cited, relative to tlio 

 absorptive power of soils for different water-soluble salts, and in 

 regard to the recovery of them after absorption has taken place, 

 it is abundantly clear that here is an extremely important sub- 

 ject which has, as yet, received far too little attention, either as 

 to its nature, origin, extent or relation to differences in soil fer- 

 tility. 



The results which have been cited show unmistakably, not 

 only that the absorptive power of soils for plant food ingredi- 

 ents is large, but they indicate that wide differences in this 

 power may exist between different soils. Moreover, the results 

 which have been presented, in Bulletins "B" and "C," regarding 

 the differences in the amounts of water-soluble salts which may 

 be recovered, by water alone, during very brief periods of conr 

 tact, and the relation of these amlounits to yields, make it ex- 

 tremely pertinent to inquire whether or not differences in the 

 immediate productive capacities of soils may not be indicated 

 by, if not' in part due, to differences in the amounts of plant food 

 materials which have, from time to time, been absorbed from so- 

 lutions coming in contact with them. Not only this, but it is 

 equally important to ascertain whether or not good, as contrasted 

 with poor, soil management does not bring about, through one 

 and another means, a gradual upbuilding of the absorbed essen- 

 tial ingredients of plant food. In other words, if the farmer does 

 not, in fact, by good handling and good feeding, cause the skel- 

 eton of the soil to become clothed, through this absorption pro- 

 cess, with materials which make it better capable of nourishing 

 crops. 



In view of the fact that the water-soluble salts in 8 soils were 

 being critically studied in relation to the yields of crops from 

 them, it seemed especially important to compare their absorptive 

 powers for water-soluble salts also, and a preliminary study was 

 made. 



