344 SOILS: PBOPEBTIJSS AND MANAGEMENT 



involved the use of centrifugal motion, which developed 

 a force of two or three thouband times that of gravita- 

 tion. When the soil contained a rather large quantity 

 of capillary water, a small amount of it could be removed 

 in this way. 



Another device, by Briggs and McCall,^ consists of a 

 close-grained, unglazed, porcelain tube, closed at one end 

 and provided at the other with a tubulure, by which it 

 can be connected with an exhausted receiver. This 

 tube is moistened and buried in the soil. If the moisture 

 content of the soil is sufficient to reduce the pressure of 

 the capillary water surface in the soil to less than the dif- 

 ference between the pressure inside and outside of the 

 tube, there will 'be a movement of water inward. This 

 water mav be collected and analyzed. 



More recently Van Suchtelen has used another method 

 to obtain the soil solution.^ He replaces the soil water 

 by means of paraffin in a liquid state, at the same time 

 subjecting the soil to suction on a filter. The displaced 

 water is considered to represent the soil solution. 



248. Composition and concentration of the soil solu- 

 tion. — ■ It has generally been held that because some soils 

 are more productive than others, and because fertilizers 

 containing soluble salts frequently increase the yields of 

 crops, the soil solution in the better-yielding soils is more 

 concentrated, at least as regards plant nutrients, than is 

 that in the poorer soils. The argument is, of course, 



1 Briggs, L. J., and MeCall, A. G. An Artificial Root for 

 Inducing Capillary Movement of Soil Moisture. Science, 

 N. S„ Vol. 20, pp. 566-569. 1904. 



2 Van Suehtelen, F. H. H. Methode zur Gewinnung der 

 Nattirlichen Bodenlosung. Jour. f. Landw., Band 60, Seite 

 369-370. 1912. 



