ACTIVE PLANT FOOD, ETC. 



191 



table 1 on page 190 the quantity of phosphoric acid withdrawn by 

 the crop is expressed as bushels of corn per acre which could be 

 produced with it. 



Potash? A similar series of experiments carried out with 

 potash lead to similar results. The percentage of deficient crops 

 decreases with the quantity of active potash in the soil. The 

 average percentage of potash in the crop increases with the per- 

 centage of active potash in the soil. The actual quantity of potash 



POTASH iu SOIL IN PARTS PER MILLION 



Fig. 42. Relation of the potash content of the crop to the 

 active potash of the soil. 



removed by the crop increases with the active potash of the soil. 

 After cropping, the soil, on analysis, was found to contain less 

 active potash than it did before cropping, showing the dis- 

 appearance of active potash due to the crop. 



RELATION OF ACTIVE POTASH TO POT EXPERIMENTS. 



1 Texas Station Bulletin 126, p. 69. 



2 Texas Station Bulletin 145. 



