14 



N. H. AGE. EXPERIMENT STATION. 



[Bulletin 170 



In order to show in a comparative way the relative amount 

 of potassium oxide taken up by the crop under different condi- 

 tions, all of the lines of the preceding figures have been plotted 

 together in Figure 7. 



Fi c 7 





% 



/zo 





 



The number of the lines in this figure correspond to the num- 

 ber of the respective figures from which they were taken. 



In connection with the use of fertilizers on soils and their 

 effect on the composition of the crop, it is interesting to note what 

 becomes of the fertilizers when they are applied to the soils. 

 When dilute solutions containing potassium salts are perco- 

 lated through columns of soil, the potassium is removed from 

 solution and changed into a more or less insoluble form. If the 

 salt is the nitrate, chloride, or sulphate, the acid radical remains 

 in solution as the acid radical of some new salt. If the salt is a 

 phosphate, both the acid and basic radicals are left behind and 

 no new salt appears in the percolate as in the other cases. The 

 same conditions hold when potassium salts come in contact with 



