Lysimeter Experiments 



57 



example, the quantity of potassium in the crops raised on tanks 6 and 10 

 was considerably smaller than that contained in the crops on tanks 3, 5, 

 7, and 9, and yet the quantity in the drainage water was not materially 

 different, as is shown by table 42, compiled from the figures in table 40 

 (page 55) . This is in line with the results given in the preceding table, 

 which showed that the potassium leached from the planted soil amounted 

 to about three-fourths of that removed from the bare soil. 



TABLE 42. Average Removal of Potassium in Drainage Water from Tanks with 

 Larger and with Smaller Quantities of Potassium in the Crops 



(In pounds per acre) 



Tanks 



Potassium 

 in crops 



Potassium 



in drainage 



water 



3, 5, 7, 9. 

 6, 10... 



89.0 



58.2 



45.5 

 46.6 



Ths effect of plant growth on the concentration of potassium in the 

 drainage water is shown in table 43: 



TABLE 43. Average Potassium Content of Drainage Water from Planted and 



from Unplanted Tanks 



Tanks 



Soil treatment 



Potassium 

 water 



(parts per 

 million) 



3, 5, 6, 7, 9, 10 

 4,8 



12.4 

 10.1 



It will be remembered that the volume of percolate from the bare soil 

 was considerably greater than from the planted soil, which is probably, 

 in part at least, the explanation for the more dilute condition of the water 

 from the bare soil. 



As between the drainage water from tanks containing smaller quantities 

 of potassium in the crops and those containing larger quantities, there 

 is no material difference in concentration, as is shown in table 44: 



57 



