124 EXPERIMENT STATION RECORD. [Vol.40 



copper, bismuth, aluminum, iron, and zinc were not found to have any invert- 

 ing power. Many suspended substances having no inverting power alone were 

 found to produce inversion when a neutral salt was present, through selective 

 adsorption of the base, thus setting a small amount of acid free. 



"'Soil acidity' is the term customarily applied when Infertility of soil can be 

 corrected by the use of a free base, such as lime. There are many factors in- 

 volved in causing this condition in soils, the presence of real acids being only 

 one of them. Methods used for detecting or determining ' soil acidity ' generally 

 do not measure the acid there but may depend upon many properties of soil 

 mass in no way related to acidity. The power of a soil to catalyze the reaction 

 of cane sugar inversion is a measure of its acid, and is probably the only method 

 which can measure the acid bound up with the soil solid pha 



A bibliography of 105 titles is appended. 



The chemical effects of CaO and CaCO, on the soil.— I. II (Soil Sri.. 5 

 (1918), Wo. .5, pp. 879-892). — Investigations with water extracts (E. S. K., 38, 

 pp. 812, 81.°.). osmotic pressures ( K. S. R., 38, p. S13), and soil reactions 

 (E. s. R., 36, p. 117), made at the California Experiment station, led to further 

 observations concerning the effects of lime upon the soil as evidenced by those 

 methods of study. The experimental work has been divided into two parts as 

 follows : 



I. The effect on soil reaction, by D. n. Hoagland and A. W. Christie (pp. 

 379 :',vj). — Clay adobe, sandy loam, and silty clay loam soils wen 1 used in this 

 Investigation In addition to beacb sand. Two 20-lb. lots of each soil were placed 

 in earthenware pols and commercial quicklime added in 1 ho proportions of 

 0.07 and 0.28 per cent, respectively, calculated in terms of pure calcium oxid. 

 The soils were maintained at approximately an optimum moisture content for 

 six months. Samples were taken at intervals during this period and the Il-ion 

 concentration determined by the hydrogen electrode method. 



The Initial effect of both low and high percentages of calcium oxid was to 

 Increase greatly the OH-ion concentration in all the soils examined, the reaction 

 of the clay adobe being Least affected and that of the beacb sand most affected. 

 The influence decreased with time, but was more marked than In the case of the 

 untreated soil or that treated with calcium carbonate even after i" months. 



Growing barlej on soil in contact with calcium oxid for six months failed to 

 produce any* significant change in the OH-ion concentration, and no inhibition 

 of plant growth was observed. 



With the addition Of an excess of calcium oxid to an acid fine sandy loam soil, 

 nitrification was practically inhibited due to the high concentration of OH-ion, 

 while similar soil treated with calcium carbonate gave 100 per cent nitrification. 



II. The effect on water-soluble nutrients in noils, by a. \y. Christie and .V C. 

 Martin (pp. 383-392*). — The direct chemical effects of calcium oxid and calcium 

 carbonate on the water-soluble calcium, magnesium, potassium, phosphate, sul- 

 phate, and nitrate in seven different soils, including sandy loam, tine sandy 

 loam, silty clay loam, and clay adohe, were studied. Previous soil treatments 

 included either leaching, storing, cropping, or fallowing Data on the osmotic 

 pressure of the soil solutions as determined by the freezing-point method t 

 also presented. 



Six 500-gm. portions of each air-dry soil were used and duplicate appllca- 

 tions made of 0.5 gm. of calcium carbonate and 0.28 gm. of calcium oxid. The 

 soils were maintained at an optimum moisture content for one week and then 

 analyzed. In order to demonstrate more fully the direct effect of lime, 0.4 I" P 

 cent calcium oxid was added to n silty clay loam soil and allowed to stand 

 only 24 hours before analysis. The results obtained indicated the immediate 

 chemical effects of quicklime. 



