352 SOILS: PROPERTIES AND MANAGEMENT 



5O/L 



FIG. 55. Curves showing the absorption of PC>4 in parts to a million 

 by various soils from a solution of monocalcium phosphate, contain- 

 ing 200 parts to a million of PC>4. The volume of the percolate is 

 used as the abscissas. 



Note. The law which appears to govern absorption of phos- 

 phates and potash by the soil may be expressed mathematically 

 as follows : 



in which K is a constant, A the maximum quantity possible 

 for the soil to absorb, and y the quantity actually fixed when v, 

 volume of the solution, has percolated through. 



A short discussion of the mathematics of this law may be 

 found in the following publication : Schreiner, O., and Failyer, 

 G. H. The Absorption of Phosphates and Potassium by Soils. 

 U. S. D. A., Bur. Soils, Bui. 32, pp. 23-24, 37-39. 1906. 



