No. 1, February, 1921] SOIL SCIENCE 69 



t"he soil and increased the crop yield. The reduction in acidity is due to the formation of insol- 

 uble aluminum salts. Leaching soil with potassium nitrate until the leachings are neutral 

 removes as much as 59 per cent of the aluminum, reduces the acidity 99 per cent, and improves 

 the growth of sweet clover. Iron and manganese are apparently not important factors in the 

 soils studied. — W. J. Robbins. 



450. Shedd, O. M. a proposed method for the estimation of total calcium in soils and the 

 significance of this element to soil fertility. Soil Sci. 10: 1-14. 1920. — A rapid and accurate 

 method for the determination of total calcium in soils is described. The total calcium 

 content of some Kentucky soils is so low that their deficiency in this substance is important, 

 as well as is the deficiency in phosphorus and nitrogen. Cultivation causes a loss in calcium. 

 The best soil types contain the most calcium; the poorest, the least. A ton of limestone or 

 rock phosphate per acre may add more calcium than is already present. — W. J. Robbins. 



INFLUENCE OF BIOLOGICAL AGENTS 



451. Greaves, J. E. The antagonistic action of calcium and iron salts toward other salts 

 as measured by ammonification and nitrification. Soil Sci. 10: 77-102. W fig. 1920. — A 

 determination was made of the ammonification and nitrification of dried blood in soil in 

 tumblers to which salts in fractions of gram molecules were added. True antagonism as 

 measured by ammonification was found between calcium sulphate, and sodium carbonate, 

 sodium nitrate, sodium sulfate, calcium chloride, magnesium chloride, and magnesium sul- 

 phate. The same is true of nitrification with the exception of sodium sulphate and calcium 

 chloride and calcium sulfate. With some exceptions, the sulphate, chloride, carbonate, and 

 nitrate of iron were found to antagonize the salts of sodium, calcium, and magnesium. Iron 

 carbonate reduced the toxicity of magnesium sulphate to ammonification 75 per cent, artd 

 iron nitrate increased the nitrification in the presence of magnesium chloride 420 per cent. 

 The quantity of iron required for maximum effect varies with the iron compound and the 

 specific alkali. — W. J. Robbins. 



452. Greaves, J. E. The influence of arsenic upon the biological transformation of 

 nitrogen in soils. (Abstract.) Utah Acad. Sci. 1 : 128-129. 1918.— Complete paper published 

 in Biochem. Bull. 3: 2-16. 1913. 



453. Peterson, E. G., and E. Mohr. Nitrogen fixation by bacteria in Utah soils. 

 (Abstract.) Utah Acad. Sci. 1 : 97-98. 1918. 



454. Neller, J. R. The oxidizing power of soil from limed and unlimed plots and its rela- 

 tion to other factors. Soil Sci. 10: 29-39. Fig. 1, pi. 1. 1920.— The carbon dioxide evolution, 

 and nitrate and ammonia production, from added organic matter were determined for soil 

 samples from plots which have been cultivated for more than ten years under limed and 

 unlimed conditions. Nitrate accumulation and bacterial numbers were higher on the limed 

 than unlimed soil, but the ammonia accumulation was about the same. The average crop 

 yield for the past ten years varies closely with the present oxidizing power. — W. J. Robbins. 



455. Robbins, William J., and A. B. Massey. The effect of certain environmental 

 conditions on the rate of destruction of vanillin by a soil bacterium. Soil Sci. 10: 237-246. 

 1 fi^. 1920. — Studies in solution cultures containing nutrient salts show that the destruction 

 of vanillin by a soil bacterium is favored by aeration and inhibited by slight concentrations 

 of hydrochloric acid. In mixtures of sodium nitrate, potassium sulfate, and calcium acid 

 phosphate, the destruction of vanillin is most rapid in the cultures high in phosphate and 

 least rapid in cultures high in sulfate. The number of species capable of destroying vanillin 

 is limited. — W. J. Robbins. 



456. Singh, Thakur Mahadeo. The effect of gypsum on bacterial activities in soils. 

 Soil Sci. 9:437-468. 1920.— Determinations were made of the effect of calcium sulphate, 

 calcium carbonate, or combinations of the two on the ammonification of dried blood, nitri- 



