356 NATURE AND PROPERTIES OF SOILS 



acre. Calcium hydroxide and calcium carbonate are often 

 used. 



Many investigators consider that the hydrogen ion concen- 

 tration of the soil solution is a fair measure of the lime re- 

 quirement of a soil. 1 They thus assume that the concentra- 

 tion of the hydrogen ion is a comparative indication of the 

 amount of lime necessary to alleviate the detrimental influ- 

 ences due to acidity. Bouyoucos 2 claims that the depression 

 of the freezing point (see par. 145) may be used to measure 

 soil acidity. He found that the depression of the freezing 

 point was less for a neutral soil than for one either acid or 

 alkaline. 



192. The Veitch method. — In order to show something 

 of the procedure necessary in determining the lime require- 

 ment of the soil, the Veitch method, which utilizes calcium 

 hydroxide, will be briefly described. Eleven and and one-fifth 

 grams of soil are placed in a suitable Erlenmeyer flask and 

 treated with a standard lime-water solution. The amount of 

 soil taken and the strength of the calcium hydroxide solution 

 are such that each cubic centimeter of the latter absorbed by 

 the soil indicates the need of 300 pounds of calcium oxide 

 to the acre. A number of samples are run at the same time, 

 receiving progressively larger amounts of lime-water. The 



1 Gainey, P. L., Soil Beaction and Growth of Azotobacter; Jour. 

 Agr. Res., Vol. XIV, No. 7, pp. 265-271, 1918. 



Gillespie, L. J., and Hurst, L. A., Hydrogen Ion Concentration — 

 Soil Type — Common Potato Scab; Soil Sci., Vol. VI, No. 3, pp. 219- 

 236, 1918. 



Plummer, J. K., Studies in Soil Reaction as Indicated by the Hydro- 

 gen Electrode; Jour. Agr. Res., Vol. XII, No. 1, pp. 19-31, 1918. 



Joffe, J. H., Hydrogen Ion Concentration Measurements in Soils in 

 Connection with Their Lime Requirements ; Soil Sci., Vol. IX, No. 4, 

 pp. 261-266, 1920. 



Blair, A. W., and Prince, A. L., The Lime Requirement of Soils 

 According to the Veitch Method Compared with the Hydrogen Ion Con- 

 centration of the Soil Extract; Soil Sc : ., Vol. IX, No. 4, pp. 253-259, 

 1920. 



2 Bouyoucos, G. J., The Freezing Point Method as a New Means of 

 Determining the Nature of Acidity and Lime Requirements of Soils; 

 Mich. Agr. Exp. Sta., Tech. Bui. 27, 1916. 



