8 5 8 



Journal of Agricultural Research 



Vol. XX, No. ii 



Tablk I. — Calcium and carbon dioxid in representative Kansas soils — -Continued 



GROUP m, SOILS WHOSE INITIAL REACTION WAS MORE ACID THAN IS INDICATED BY Pa 7 



Soil 

 No. 



1141 

 1136 

 1285 

 1287 

 io 5 3 

 1284 

 1 190 

 1293 

 1191 

 "35 

 1271 

 "43 

 1256 

 1262 

 1233 

 1257 

 1265 

 1273 

 1275 

 1232 

 1277 

 1266 

 1239 

 1243 

 1280 

 1230 

 1279 

 1 148 

 1244 



County. 



Shawnee . . . . 



do 



Montgomery 



do 



Doniphan.. . 

 Montgomery 



Jewell 



Montgomery 



Jewell 



Shawnee 



Montgomery 



Shawnee 



Greenwood.. 



Montgomery 



Cherokee. . . . 



Greenwood.. 



Montgomery 



do 



do 



Cherokee. . . . 

 Montgomery 



do 



Cherokee. . . . 



do 



Montgomery 

 Cherokee. . . . 

 Montgomery 



Reno 



Cherokee 



Soil type. 



Total 

 Ca. 



Ca. solu- 

 ble in 



N/zUCl. 



Summit silty clay loam .... 



Oswego silt loam 



Crawford loam 



Summit silty clay loam. . . . 



Brown silt loam 



Crawford loam 



Jewell silt loam 



Bates stony loam 



Colby silt loam 



Crawford silty clay loam. . . 



Bates loam 



Boone fine sandy loam 



do 



Crawford loam 



Oswego silty clay loam 



Summit silty clay loam .... 



Cherokee silt loam 



Bates very fine sandy loam. 



Oswego silt loam 



Bates silt loam 



Bates shale loam 



Bates very fine loam 



Summit silt loam 



Cherokee silt loam 



Bates loam 



Neosho silt loam 



Bates very fine sand 



Dune sand 



Bates fine sandy loam 



Per cent. 

 42 



Ca. solu- 

 ble in 

 NIs HC1. 



Per cent. 

 o. 41 



.18 

 .19 

 .18 

 •15 



•13 

 .14 

 •13 

 . 10 

 .09 

 .09 

 .08 

 .07 



Per cent. 



o. 016 



.013 



None. 



Do. 

 Trace. 



None. 

 . 01 



None. 

 . 01 

 . 01 



None. 



Trace. 



Do. 



None. 



Trace. 



Do. 



None. 



Do. 



Do. 



Trace. 



None. 



Do. 



Trace. 



Do. 



None. 



Do. 



Do. 

 .00; 



Trace. 



DETERMINATION OF THE INITIAL REACTION AND THE ELECTRO- 

 METRIC TITRATION OF SOILS STUDIED 



The apparatus used in these determinations was the same as that de- 

 scribed in previous papers (12, 13). Ten gm. of soil were weighed into 

 a 250-cc bottle which was used as the electrode vessel, and 100 cc of 

 carbon-dioxid free water were added. The bottle was closed with a large 

 rubber stopper through which were inserted the hydrogen electrode and 

 the capillary tube connecting with the calomel cell. The hydrogen after 

 bubbling through the soil suspension passed through a water trap, and 

 the tip of the burette used in the titration was inserted through a hole in 

 this stopper. In this way contamination from the carbon dioxid in the 

 air was prevented. These precautions are necessary, since these deter- 

 minations require a number of hours. 



The distilled water used in this work was freed from carbon dioxid by 

 aeration. While water so treated is not as neutral as conductivity water, 

 the purity was sufficient for these determinations. The reaction of va- 

 rious samples of this water ranged from P H 6 to P H 6.6. One-tenth cc. of 

 N/io alkali would change the concentration from about P H 6 to P H 8. 

 The error due to the water is therefore small. After the apparatus was 

 adjusted, the hydrogen gas was bubbled through until equilibrium was 

 obtained. The time required for this depended somewhat on the char- 

 acter of the soil. During the entire time the electrode vessel was shaken 

 about 60 times per minute by a shaking device. As soon as the readings 

 on the millivoltmeter remained constant within a few millivolts for 15 



