Lysimeter Experiments 



45 



in the form of nitrate. This would still leave about 178 pounds of 

 calcium that had been removed from the planted soil in some form other 

 than nitrate, and about 240 pounds from the unplanted soil. However, 

 as the analyses show that there were more sulfuric acid and more silica 

 and bicarbonates removed in the leachings of the unplanted soil than 

 in those of the planted soil, this difference can thus be accounted for. 

 The large removal of nitrates in the unplanted soil is undoubtedly associated 

 with a large loss of calcium. Any management of the soil that permits 

 the nitrates to form freely and to leach out of the soil results in a large 

 loss of calcium, while maintaining a crop of some kind on the soil con- 

 serves the calcium. Catch crops conserve not only nitrogen but also 

 calcium. 



The concentration of calcium in the drainage water from the planted 

 and the unplanted soil was in the same order as its total removal. This 

 may be seen in table 24, in which is stated in parts per miUion the average 

 calcium content for the five-years period: 



TABLE 24. Average Calcium Content of Drainage Water from Planted and from 



Unplanted Tanks 



Tanks 



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

 4,8 



Soil 

 treatment 



Calcium 



(parts per 



million) 



47.1 

 69.3 



The greater loss of calcium from the unplanted soil was not due entirely 

 to the greater percolation of water thru that soil, as in that case the 

 concentration would not be greater. Evidently the percolate from the 

 unplanted soil has a greater solvent power for calcium. 



The fact must not be lost sight of, however, that the bicarbonates 

 were present in the drainage water of the unplanted soil, not only in larger 

 quantity per tank, but also in slightly greater concentration than in the 

 water from the cropped tanks. Carbonic acid also is doubtless a factor 

 in the greater removal of calcium from the unplanted soil, but to a less 

 extent than nitric acid. The average concentration, in parts per million, 



45 



