130 BULLETIN "D." 



parts per million of the solution, which is equivalent to 983 to 

 1474 parts per million of the dry soil itself. 



It is especially noteworthy that these salt solutions have been 

 the mieans of dissolving very large amounts of potash from the 

 untreated soil to which none had been added, except under field 

 conditions. The amounts dissolved range between 211 and 328 

 parts per million of the soil, which means from 600 to 1000 

 Ibs. per acre-foot. The sodium chloride produced the largest 

 solution and the magnesium nitrate the least. Here, again, it 

 would have been extremely helpful if an untreated sample had 

 been washed in distilled water as one of the same series. In 

 the case of the treated soil, which was washed in distilled water, 

 there was redissolved, as shown in the last line of the table 

 173.6 parts per million of the solution of K 2 O, or 434 parts per 

 million computed on the soil; and this, when the solution was 

 only 2.^ times the weight of the soil. It is, therefore, clear 

 that however the potash was fixed in this soil, it was still, in a 

 high degree, soluble in distilled water. 



Referring to the right section of the table, p. 129, and com- 

 paring the amounts of soda, ammonia, lime and magnesia, 

 which were absorbed from the solutions by the soil, with the 

 amounts of potash brought into solution, as indicated in the 

 KoO column, it will be seen that the largest absorption of these 

 bases has taken place where the largest solution of potash has 

 occurred; nevertheless, the relative amounts are not such as 

 would be expected by a simple chemical replacement. 



OBSERVATIONS OF O. KULLENBERG.* 



The soil used for the study of the absorption of potash was 

 the same as that cited on p. 118. The salts used, the strengths of 

 the solutions and the amounts of potash absorbed are given in 

 the next table. 



*Hoffman's Jahresbericht der Agrikultur-Chemie, 1865, p. 15. 



