16 



N. H. AGR. EXPERIMENT STATION, 



[BuUetin 170 



Excepting phosphates, all the solutions were destructive in re- 

 spect to the soil itself; but, in the process of destruction, new 

 bases were substituted for the ones removed. 



The results obtained, when potassium chloride solution, contain- 

 ing the equivalent of 0.35 grams potassium oxide per liter, is 

 percolated through 500 gms. of soil, are shown in the following 

 table: 



Table VIII 



While lime, magnesium and small amounts of iron, alumi- 

 num, etc., become soluble, a certain amount of potassium is 

 removed from solution and retained in the soil. The data show 

 that some of the soils remove a large part of the potassium from 

 the first portions of the percolate. As more solution is perco- 

 lated through the soils, smaller quantities of potassium are re- 

 tained. While these soils contain naturally large amounts of 

 potassium, they remove additional amounts from solution. The 

 soils, richer in clay and also in potassium, retain larger amounts 

 than the lighter soils which are relatively poorer in clay and 

 potassium. 



When the soil which has taken up potassium is washed con- 

 tinuously with water, more and more of the potassium goes 

 into solution. However, it is very difficult to recover all the 

 potassium after it is once taken up by the soil. When potassium 

 is supplied as a fertilizer, it forms a more concentrated soil solu- 

 tion during the time that these adjustments are taking place. 

 During this time, the plant should take up an excess of potas- 

 sium 



