22 



Journal of Agricultural Research 



Vol. XII, No. I 



Table I. — Hydrogen-ion concentration of soil suspensions — Continued 



Sample 

 No. 



Soil type. 



Depth. 



Volt- 

 meter 

 readings. 



H-ion concen- 

 tration. 



I202 

 1372 



1373 

 674 



684 



68s 

 1007 

 1212 

 1077 

 2526 



Porter's loam 



do 



do 



Porter's clay 



do 



do 



do 



Muck 



do 



do 



do 



Chickamauga limestone soil«. 



Chickamauga limestone soil &. 



Cumberland loam « 



Cumberland loam & 



Tillico sandy loam a 



Inches. 

 8-30 



o-l 



7-24 

 0-7 

 7-24 

 0-6 



6-20 



0-18 



0-24 



0-36 

 0-36 



• 639 



.647 



• 639 



•577 

 .566 



•594 

 •587 

 •483 

 . 462 



•536 

 .427 

 .864 

 .824 



•893 

 .856 

 .866 



Gram rtiole- 

 cules per liter. 

 .5X10-5 

 .3X10-5 

 .5X10-5 

 .6X10-* 

 .1X10-3 

 .3X10-* 

 .4X10-* 

 .2X10-2 

 .6X10-2 

 .3X10-3 

 .2X10-1 

 .7X10-9 

 .3X10-8 

 .2X10-9 

 .9X10-9 

 .6X10-9 



o Treated in 1912 with 16,000 pounds of calcium carbonate per acre in excess of Vietch indication. 



6 Treated in 1912 with MgCOsOCaCOs at rate of 16,000 pounds per acre in excess of Vietch indication. 



The results shown in Table I indicate wide variations in the H-ion 

 concentrations of the untreated soils under experiment. This vaijies 

 from very nearly neutral in some of those of the Iredell series to rather 

 excessive acidity in the Norfolk silt loam and mucks. This is in accord 

 with what would be expected. The Iredell soils are of residual origin 

 formed from basic eruptions, mainly diorite. The amount of basic 

 elements supphed this soil is greatly in excess of those commonly found 

 in the area included in this study. The Norfolk silt loam being a trans- 

 ported soil, was formed under conditions through which the basic ele- 

 ments have been removed. It also contains rather high amounts of 

 partially decomposed organic matter, and should show a high concen- 

 tration of H over OH ions. Field and pot tests with various crops have 

 shown indications of excessive acidity on some of the muck soils. Indeed 

 on some of the muck fields from which the samples were taken little or 

 none of the common agricultural crops will thrive until the land has 

 been limed. 



No definite relationship appears to exist between the H-ion concen- 

 tration and types of different texture. It can be noticed that there is a 

 tendency for the H ion to increase as the number of fine particles increase 

 in a series. However, there are exceptions. The clay loams and loams 

 of the Iredell and Porter's series show greater H-ion concentration than 

 do those of coarser texture. It may be observed that in many cases the 

 subsoil shows a greater degree of acidity than the corresponding surface 

 soil. The general practice in farming these soils has been the removal 

 from the land of all crops. Probably there is a tendency for plant roots 

 to remove more bases from lower depths than from the surface. 



