Mar. i, 1921 



Relation of Calcium Content to Soil Reaction 



857 



those soils which were thought most suitable were selected. In the 

 description of these soils, the type names given by the Bureau of Soils 

 are used. The soil numbers are those found in our soil series. The 

 samples had been taken usually in three strata — namely, surface o to 

 7 inches, subsurface 7 to 20 inches, and subsoil 20 to 40 inches. For 

 this work, surface soils mostly were selected, with a few accompanying 

 subsoils. The soil number has a whole figure and a decimal. A surface 

 soil is designated as 1083. 1, subsurface as 1083.2, and a subsoil as 1083.3. 

 Some of the samples were taken in only two strata. 



The figures given for total calcium and carbon dioxid are taken from 

 the publications to which reference has been made. In addition the 

 authors have determined the calcium soluble in Nji hydrochloric acid 

 and in NJ5 hydrochloric acid and the reaction as determined by the 

 hydrogen electrode with accompanying titrations. 



DETERMINATION OF ACID-SOLUBLE CALCIUM 



Five gm. of soil were placed in 100 cc. Nji hydrochloric acid and 

 shaken for one hour on a shaking machine, then placed in a thermostat 

 at 40 C. and digested for 23 hours with occasional shakings. The 

 acid-soluble calcium was determined by the volumetric permanganate 

 method. The treatment with NI5 hydrochloric acid was similar ex- 

 cept that 10 gm. of soil and 200 cc. of the acid were used. The results 

 on the calcium determinations are given in Table I. 



Table I. — Calcium and carbon dioxid in representative Kansas soils 



GROUP I, SOILS WHOSE INITIAL REACTION WAS MORE ALKALINE THAN IS INDICATED BY PH 8.3 



Soil 

 No. 



1043 

 1227 

 1297 

 "99 

 I206 

 1 186 

 I"5 

 III9 

 1169 



County. 



Russell 



Greenwood.. 

 Montgomery 



Jewell 



do 



Reno 



Finney 



do 



Reno 



Soil type. 



Benton loam 



Crawford clay 



Oswego silt loams 



Laurel very fine sandy loam. 



Lincoln silty clay loam 



Kirkland clay loam 



Richfield silt loam 



Pratt loamy fine sand 



....do 



Total 

 Ca. 



Per 



Ca. solu- 

 ble in 

 Nil HC1. 



Per cent. 

 4. 01 



Ca. solu- 

 ble in 

 NI5 HC1. 



Per cent. 

 4. 19 

 3- 18 

 I- 03 

 ■53 

 .69 

 •47 

 .28 

 .09 

 •°S 



CO2. 



Per cent. 

 37 



Trace. 

 Do. 

 • 009 



GROUP II, SOILS WHOSE INITIAL REACTION WAS BETWEEN PH 8.3 AND PH 7 



1219 

 IO47 

 I039 

 1132 

 1268 

 I267 

 II2I 

 II3I 

 IO7O 

 1157 

 1120 

 I072 

 Il62 

 II60 



Greenwood . . 



Brown 



Russell 



Shawnee. . . . 

 Montgomery 

 do 



Finney 



Shawnee 



Reno 



do 



Finney 



Harper 



Reno 



do 



Osage loam 



Silt loam (bottom) 



Summit silty clay loam 



Osage silty clay loam 



Osage clay (alfalla land) 



Osage silty clay loam 



Finney clay 



Osage very fine sandy loam . 



Pratt loam 



Arkansas clay loam 



Sandy loam 



Brown loam 



Pratt fine sandy loam 



Arkansas fine sand 



.04 

 .16 



Trace 



None 



Do. 



Trace. 



Do. 



Do. 

 .003 



Trace. 



None. 

 .003 

 .002 



29666 c 



