44 



T. Lyttleton Lyon and James A. Bizzell 



soil, but it is greater than the quantity contained in the drainage water 

 and the crops combined. The average amount of calcium removed 

 in crops and drainage water from the planted tanks, and the average 

 amount in the drainage water of the unplanted tanks, are given in table 22: 



TABLE 22. Average Annual Removal of Calcium from Planted and from 



Unplanted Tanks 



(In pounds per acre) 



Tanks 



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



4,8 



Soil 

 treatment 



Planted 

 Bare . . . 



Calcium conserved by cropping. . 



Calcium removed in 



Drainage 

 water 



173.3 

 367.4 



Crops 



13.2 



Total 

 calcium 

 removed 



186.5 

 367.4 



180.9 



The process of cropping conserves the calcium in the soil even when 

 the entire crop is removed. The reason for the greater removal of calcium 

 from the uncropped soil may be found, in part at least, in the large for- 

 mation and leaching of nitrates when plants are not present. In table 23 

 is shown the average amount of nitrates found annually in the drainage 

 water of the planted and the unplanted tanks: 



TABLE 23. Average Annual Removal of Nitrates from Drainage Water in 



Planted and in Unplanted Tanks 



Tanks 



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



•4,8 



Soil 

 treatment 



Nitrates 

 removed 

 (pounds 

 per acre) 



21.3 

 393.6 



The nitrates in the drainage water from the cropped soil would account 

 for only about 8 pounds of calcium, while the nitrates from the unplanted 

 soil correspond to about 127 pounds of calcium which might be removed 



44 



