268 NATURE AND PROPERTIES OF SOILS 



It is noticeable that the absorption increases with the fine- 

 ness of the texture, indicating that the heavier the soil, the 

 greater is the amount of material present that possesses marked 

 capacity for fixation. Organic matter, in general, does not 

 seem as efficacious as mineral material in absorptive reac- 

 tions, especially those involving salts. 



200 



400 



600 



600 



1000 



??00 CC. 



Fig. 49. — Curves showing the absorption of K in parts per million by 

 various soils from a solution containing 200 parts to the million of 

 K. The volume of the percolate is used as the abscissas. 



The influence of time on absorption is shown by the follow- 

 ing data from Schreiner and Failyer. 1 In this case 100 gram 

 portions of soil were treated with 500 c.c. of a mono-calcium 

 phosphate solution carrying 100 parts per million of P0 4 . The 



1 Schreiner, O., and Failyer, G. H., The Absorption of Phosphates 

 and Potassium by Soils; U. S. Dept. Agr., Bur. Soils, Bui. 32, p. 9, 

 1906. 



