1919] SOILS FERTILIZERS. 321 



salts were present. The toxic point of tlie coml)ine(l salts depended upon the per- 

 centages of the chlorids, nitrates, carbonates, and sulphates present and the 

 combination in whicli they existed. Calcium sulphate, when present, lowered 

 the toxic point of the chlorid, carbonate and nitrate of sodium. 



Notes on recent work concerning' acid soils, L. T. Sharp and D. R. Hoagland 

 (Soil Sci., 7 (1919), No. 3, pp. 197-200). — The authors refer to previous reports 

 by Gillespie and Hurst (E. S. R., 38. p. 620) and Rice and Osugi (E. S. R., 40, 

 p. 123) bearing on the subject, and since they disagree with the latter report a 

 number of experiments were conducted at the California Experiment Station 

 on the inverting power of soils and their extracts. The soil or soil extract was 

 heated with a 10 per cent sugar solution at 85° C. for one hour and the amount 

 of copper reduced determined. 



It was found that soils of the highest hydrogen-ion concentration caused the 

 greatest inversion, and the very slightly acid soils and alkaline soils gave only a 

 slight inversion. A marked inversion was also produced by the extracts of the 

 soils of high hydrogen-ion concentration. A larger inversion resulted when the 

 sugar solution was heated in the presence of the solid soil particles. 



It is concluded that " large inversion occurs only in soils of distinctly acid 

 reaction, with the greatest inversion occurring coincidently with the highest 

 H-ion concentration of the soil suspension as well as of the water and the 

 sugar extracts." 



Direct evidence was also obtained that acid soils do give acid filtrates, giving 

 acid reactions generally of a magnitude very similar to those obtained with the 

 suspensions. Boiling the extract for several minutes produced no large changes 

 in hydrogen-ion concentration. 



Determination of the rate of solution of atmospheric nitrogen and oxygen 

 by water, W. E. Adeney and H. G. Becker (Sci. Proc. Roy. Dublin Soc, n. ser., 

 15 (1918), pp. 385-404; abs. in Jour. Chem. Soc. [London], 116 (1919), No. 677, 

 II, pp. 104, 105). — Experiments are reported, the results of which confirm pre- 

 vious conclusions by the authors to the effect that the gases are absorbed by the 

 surface layer of the water but do not remain concentrated there, diffusing 

 gravitationally through the lower layers of the water with comparative rapidity. 



Can w^e predict probable fertility from soil biological data? P. S. Btjrgess 

 (Soil Sci., 6 (WIS), No. 6, pp. ^-^9-7/62).— Experiments at the Hawaiian Sugar 

 Planters' Station are reported, the purpose of which was to determine the rela- 

 tion between microbiological data and the crop-producing powers of the soil. 

 Tests of ammonification, nitrification, total organic nitrogen supplied rendered 

 water soluble, and nitrogen fixation were conducted in 9 Hawaiian sugar-cane 

 surface soils, using dried blood, fine alfalfa meal, and fish scrap. Three of the 

 soils were exceptionally fertile, 3 were capable of producing good average crops, 

 while 3 produced poor crops of cane after fair fertilizer applications. 



It is concluded that " ammonification tests are not suitable to differentiate 

 between the fertilities of average Hawaiian soils, although they will often 

 show differences between very poor and very good soils. The abilities of soils 

 to render organic nitrogen (of blood or alfalfa) winter-soluble are of no value 

 as measures of their crop-producing powers." Nitrification is considered by 

 far the most accurate biological soil test for predicting the probable fertility 

 of Hawaiian soils. There was a remarkable correlation between the amounts 

 of nitrogen fixed in mannite solution cultures and the known fertilities of the 

 soils studied. There was little difference in the comparative rating of the soils, 

 depending upon whether nitrification or nitrogen fixation tests were used as the 

 criteria of fertility. 



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