LIMIT OF PHYSIOLOGICAL WATER 



51 



less silt and clay. Hence these were more porous than clay 

 and the forces of capillarity and surface tension in them 

 must have been less powerful. Since the limit of these soils 

 is higher than that of clay there is evidently another disturb- 

 ing factor, especially in the case of the saline and humus soils. 

 This must be attributed largely to the increased amount of 

 electrolytes or soluble salts in the soil. T^e following table 

 of ratios includes a comparison of the soils taking the per 

 cent in loess as a basis and calling this 1.00 in each column. 

 It may be seen that the per cent of soluble salts varies ap- 

 proximately with the increased amount of non-available wa- 

 ter. The variation of the other soil qualities shows no uni- 

 formity, when compared with each other or with the non- 

 available water. 



Table of Comparative RatAos. 



After much effort to combine these ratios to get a common 

 ratio which would correspond to that of the non-available 

 soil water, it was found that the ratios of soil solution were 

 the only ones that compared directly with those of the non- 

 available water. It was found that if tbe per cent of so- 

 lution be taken as a basis, and the square root extracted and 

 multiplied by 20, a set of ratios or numbers were obtained 



