Jan. 7, 1918 



Studies in Soil Reaction 



29 



phenomena. The contention that the base has been removed by com- 

 bination with the difficultly soluble acids more nearly agrees with the 

 results obtained. The measurements showing the effect of monocal- 

 cium phosphate on the H-ion concentration of soil-film water are given 

 in Table VIII. 



Table VII. — Effect of ammonium sulphate on the H-ion concentration of soil-film 



water 



Table VIII. — Effect of monocalcium phosphate on the H-ion concentration of soil- 

 film luater 



Soil type. 



Quan- 

 tity of 

 soil. 



Quan- 

 tity of 

 mono- 

 calcium 

 phos- 

 phate 



Mois- 

 ture 

 con- 

 tent, 

 dry 

 basis. 



Mois- 

 ture 

 recov- 

 ered. 



Vol- 

 ume of 



film- 

 water. 



Volt- 

 meter 

 read- 

 ings. 



H-ion concen- 

 tration. 



Cecil clay loam 



Do 



Do 



Porter 's loam 



Do 



Do 



Norfolk fine sandy loam 



Do 



Do 



Pounds. 

 10 

 10 

 ID 

 10 

 10 



Cm. 

 10 

 20 



30 

 10 

 20 

 30 

 10 

 20 

 30 



Per 

 cent. 



25 

 25 

 25 

 25 

 25 

 25 

 20 

 20 

 20 



562 



598 

 602 

 562 

 602 

 591 



Gramrmolecules 

 per liter. 

 0.4X10-4 

 .3X10-* 

 ■3X10-^ 

 .2X10-* 

 . 2 X IO-* 

 .1X10-3 

 .2X10-* 

 •3X10-" 

 .4X10-* 



By comparing the data of Table II with those derived from this experi- 

 ment it is apparent that only excessive applications of monocalcium 

 phosphate have increased the H-ion concentration. The 20-gm. appli- 

 cations of the salt do not show any increase in "true acidity" with any 

 soil used. The clay loam and loam give a higher H-ion concentration 



