282 NATURE AND PROPERTIES OF SOILS 



Table LXI 



THE CONCENTRATION OF THE SOLUTION OF VARIOUS SOILS AS DE- 

 TERMINED BY THE DEPRESSION OF THE FREEZING POINT. EX- 

 PRESSED IN PARTS PER MILLION BASED ON DRY SOIL. 



147. Quantitative composition of the soil solution. — 

 Data regarding the relative or actual quantities of the nutri- 

 ent elements in the soil solution are not only very meagre but 

 unreliable. Morgan * found, on comparing the solutions ob- 

 tained from different soils by the oil pressure method, that the 

 potassium (K) might vary from 4 to 180 parts per million 

 based on dry soil; the phosphorus (P0 4 ) from .2 to 4.6, and 

 the calcium (Ca) from 6 to 1000 parts per million. King, 2 in 

 his extensive work with soil extracts, found the nitrate nitro- 

 gen (N0 3 ) extremely variable, ranging from a fraction of a 

 part per million to more than 150 parts per million in the same 

 soil at different times. A greater fluctuation is to be expected, 

 however, in the nitrate nitrogen than with the other elements, 

 since the presence of soluble nitrogen in the soil solution is due 

 very largely to biological activity. The following figures from 

 Morgan, although the different samples should not be com- 

 pared, show what may be expected in general regarding the 

 concentration of particular elements in the soil solution. 



1 Morgan, J. F., The Soil Solution Obtained by the Oil Pressure 

 Method; Mich. Agr. Exp. Sta., Tech. Bui. 28, 1916. 



2 King, F. H., Investigations in Soil Management ; U. S. Dept. Agr. 

 Bur. Soils, Bui. 26, 1905. 



