352 SOILS: PROPERTIES AND MANAGEMENT 













y^j-AY 



3DOO 





\y 



^ 



ClAV 



LOAM 



ZGO^; 



/ ^.^^ 



^ 



^ 



- ^A/YDY 



^O/JL 



M/ytf //y 



'/y 



y^ 









/ 













i? /c 



wo 



£6 



acf 



'3C 



GO 



^4ai 



oo soe^o cc- 



Fig. 55. — Curves showing the absorption of PO4 in parts to a million 

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

 ing 200 parts to a million of PO4. The volume of the percolate is 

 used as the abscissas. 



Note. — The law whioh appears to govern absorption of phos- 

 phates and potash by the soil may be expressed mathematically 

 as follows: — 



§1 

 dv 



= K{A - y) 



in which JC 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, 0., 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, 



