5G 



T. Lyttleton Lyon and James A. Bizzell 



while there was an average of 367.4 poiindis of calciiini leached from 

 each acre of unplanted soil and only 12.0 pounds removed in the average 

 crop. The other bases resemble calcium in having a greater removal in 

 the drainage water from unplanted soil than in the crops raised on the 

 planted tanks. 



TABLE 41. Average Annual Removal of Potassium from Planted and from 



Unplanted Tanks 



(In pounds per acre) 



Tanks 



3, 5, 6, 7, 9, 10. 



4,8 



Soil treatment 



Planted 

 Bare . . . 



Potassium removed in 



Drainage 

 water 



45.9 

 61.0 



Crops 



78.8 



Potassium conserved by not cropping . 



Total 



potassium 



removed 



124.7 

 61.0 



63.7 



Plant growth on this soil appeared to have a depressing influence on 

 the removal of calcium, if one is to judge from the fact that less calcium 

 was removed from the planted soil in drainage and crop combined than 

 from the unplanted soil in which drainage was the only means of removal. 

 On the other hand, plant growth exerted a stimulating effect on the 

 removal of potassium when judged by the corresponding data on that 

 base, appearing in table 41 above. It is seen by that table that there 

 was about twice as much potassium removed from the planted soil as 

 from the unplanted soil, and hence it may be inferred that the removal 

 of potassium by the crop has little or no effect on the quantity leached 

 out by the drainage water. This apparently greater solubility of potassium 

 in the planted soil is probably not due to the greater solvent action of 

 the carbon dioxide excreted by plant roots, as analyses of the soil air 

 of these tanks show that there is enough carbon dioxide in the unplanted 

 soil as well as in the planted soil to keep the soil water saturated during 

 the growing season. 



It made little difference in the quantity of potassium removed by the 

 drainage water whether the crops removed more or less potassium. For 



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