ABSORPTION OF SALTS BY SOILS. 



125 



RECOVERY OF ABSORBED POTASH. 



Dr. Peters made a series of observations to measure the 

 amounts of absorbed potash he could recover again from the soil 

 after absorption had taken place, using distilled water. Work- 

 ing with some of the same soil, he digested 100 grams 24 hours 

 with 250 c. c. of a potassium chloride solution containing 2.3555 

 grams per liter of K 2 O. At the end of this time he drew off 

 125 c. c. of the solution, replacing as much more distilled water, 

 repeating the operation at the end of succeeding 24 hours, until 

 he had obtained the 10th extraction. From his analyses and 

 computations he determines that the following amounts of pot- 

 ash, which had been observed, were redissolved by the action 

 of the cold water. 



Amounts of absorbed potash redissolved by water in successive 



treatments 



In the first series the original absorbed amount of K 2 O was 

 1937 and in the second 2114 parts per million of the soil; there 

 were, therefore, still left in the soil 



First series 1937-704.0=1233 parts per million of K 8 O. 

 Second series 2114875.0=1239 parts per million of K 2 O. 



The strengths of the solutions used in these various experi- 

 ments are so great that it is, perhaps, impossible to foresee what 

 would result with solutions whose strength is more nearly what 

 occurs in average field soils. 



Starting again with 1000 grams of soil placed in a large 

 flask, he added 1000 c. c, of >a potassium chloride solution con- 

 taining 28.8066 grams of K 2 O. The soil absorbed, according 



