720 EXPERIMENT STATION RECORD. [Vol.40 



At the end of the experiments the different soil layers were sampled and the 

 amount of calcium occurring in the two untreated layers determined. The 

 data are presented in tabular form and have been subjected to a statistical 

 interpretation. The results may be summarized as follows : 



Neither small nor large amounts of calcium applied to the surface layer of 

 a clayey silt loam soil in the form of burned limestone, ground limestone, or 

 precipitated calcium carbonate moved downward in the soil to any appreciable 

 extent when the soil was leached in pots for one year with distilled water. 

 Similar applications of calcium made to the bottom layer of soil failed to show 

 any upward diffusion. The fineness of division of ground limestone did not 

 influence the movement of calcium through the soil, there being no apparent 

 difference between that ground to pass a 200-mesh sieve and that held on a o^-uiesh 

 sieve. Precipitated calcium carbonate gave similar results. Oats grown on soil 

 treated with calcium oxid did not bring about a descent of calcium to the un- 

 treated soil layers. 



Continuing further, the author states that " it seems logical to believe that a 

 soil deficient in calcium will absorb this constituent from the drainage water 

 as it percolates through the soil. No doubt this occurs, but the amount held by 

 the soil is evidently so small that it can not be detected by a chemical analysis. 

 Conclusions drawn from small differences of calcium found in soil upon analysis 

 are hardly trustworthy, as it is often difficult to obtain concordant results from 

 the same sample of soil. When small differences are calculated to pounds of 

 calcium in an acre-foot of soil,. as is often done, the real value of such results 

 is questionable." 



On an electrical method of determining the lime requirement of soils, C. J. 

 Lyxde (I'ror. and Trans. Boy. 8oo. Canada, 3. scr., 12 (1918), Sect. Ill, pp. 

 21-26). — Observations on the lime requirements of a number of field soils re- 

 ceiving different manure and fertilizer treatments are described in which a 

 comparison was made of the results found by the U>>thamsted method (!'.. S. K.. 

 33, p. 022) and by the so-called electrical method. By means of a Kohlrausch 

 bridge determinations were mad.' of the electrical resistance of solutions formed 

 by shaking 10 gm. of cadi soil with 150 cc. of distilled water of the original 

 ("a (HCOs)j solution, and of the solution formed in the Rothamsted tests by 

 shaking 10 gm. of cadi soil with 150 cc. of Ca(HCOa)> solution. 



From these data was calculated the resistance the Ca(HCOi), solution must 

 exhibit after being shaken with the soil in order to give the resistance observed 

 In the soil and Ca(HCO s )» solution, assuming that the resistance of the soil 

 solution remained constant If the calculated resistance r was greater than the 

 original resistance r, of the Ca(HCO s )j solution it was thought to indicate 

 that CaCOa had been absorbed by the soil and that the soil was acid. On the 

 other hand if r was less than n It was thought to indicate that something 

 had been dissolved from the soil, and since there was an excess of OOi in the 

 solution it was deemed likely that the substance was a carbonate and that the 

 soil was alkaline. The ratio of r to r, is believed to give a measure of the 

 alkalinity or acidity of the soil. In these tests It was noted that a ratio of 

 0.986 or less indicated an alkaline soil and that the lower the ratio the greater 

 the alkalinity, while a ratio of 1.284 or above indicated an acid soil and the 

 higher the ratio the greater the acidity. 



Soil solutions were found to have the same electrical resistance when cloudy 

 as when cleared by centrifuging. 



The effect of heat on the lime requirements of soils. II. A. NbTBS (four. 

 Amer. Soc. Agron., 11 (1919), No. 2, pp. 10, 71). — This paper, a contribution 

 from the Indiana Experiment Station, describes observations made on a residual 



