No. 1, August, 1920] SOIL SCIENCE 130 



soil causes a disappearance of nitrates and also decidedly depresses the potassium, calcium 

 and magnesium, these losses also being reflected in the total solids extracted. Considerable 

 variations in moisture contents of soils, provided the saturation point is not reached, do not 

 appreciably modify the results obtained by the water-extraction method. — F . M. Schertz. 



990. Russell, E. J. Soil making. Jour. Roy. Hortic. Soc. 44: 1-12. 1919.— This is 

 a popular discussion of soils, soil changes and soil management, based largely on experiments 

 at Rothamsted. — J. K. Shaw. 



991. Shedd, O. M. Effect of oxidation of sulphur in soils on the solubility of rock phos- 

 phate and on nitrification. Jour. Agric. Res. 18: 329-345. 1919. — Compost experiments of 

 rock phosphate, sulfur, soil and manure show after 24 months time, that about 17 and 84 

 per cent of the total phosphorus had been converted into a water-soluble and ammonium- 

 citrate-soluble form, respectively. Sulphofication did not proceed as rapidly as when an 

 inoculation was made with the sulphofying organism, and when this was done the time of 

 the sulphofication may be considered to be reduced nearly one third. Composting under the 

 same conditions but omitting the sulfur also showed favorable results in rendering the soil 

 phosphate or that added in rock sulphate soluble, but not to the same extent as when sulphur 

 was present. Nitrification was found to proceed to a certain extent regardless of the acid 

 formed by the sulphur oxidation. The amounts of nitrogen found to be nitrified amounted 

 to approximately 20 per cent of the total originally present. Sulphofication was found to 

 take place in all of the soils examined but varied somewhat according to the type. When 25 

 and 50 mgm. of sulphur were added to 100 grams of soil, about the same percentage of the total 

 was oxidized in a given time. Inoculation of mixtures of rock phosphate and sulphur was 

 not sufficient to promote rapid sulphofication. It required in addition, soil or soil water. 

 That the production of soluble phosphate was caused by the presence of sulphuric acid gen- 

 erated by the oxidation of the sulphur is demonstrated by the parallel rise in acidity and sul- 

 phate. The best conditions to promote the reaction are initial inoculation, high temperature, 

 thorough aeration, and a fair moisture content. Other contributing factors are the propor- 

 tions of the different ingredients and probably their mass. The acid phosphate made by this 

 procedure has just as good a physical condition as the commercial product and would be 

 cheaper if the time and labor involved in its manufacture are disregarded. — F. M. Schertz. 



992. Shull, C. A. Soil fertility. [Rev. of: Van Alstine, E. The movement of plant 

 food within the soil. Soil Sci. 6: 281-308. 1918. (See Bot. Absts. 2, Entry 1341.)] Bot. Gaz. 

 68:312. 1919. 



993. Takahashi, R. On the fungous flora of the soil. Ann. Phytopath Soc. Japan 1 ! ; 

 17-22. 1919. See Bot. Absts. 5, Entry 688. 



994. Watts, Francis. The liming of soils. West Indian Bull. 16: 332-341. 1918.— 

 Compiled information. — C. V. Piper. 



INFLUENCE OF BIOLOGICAL AGENTS 



995. Barthel, Chr., and N. Bengtsson. The influence of lime on the nitrification of 

 barn-yard manure — nitrogen in arable soil. Soil Sci. 8 : 243-258. 1919. Manure or ammonium 

 sulfate was added to limed and unlimed neutral and acid soils. Weekly determinations of 

 the ammonia and nitrates were made. Lime stimulated the nitrification of the ammonium 

 sulfate but exerted no favorable action on the nitrification of stable manure or in cases where 

 the supply of lime was large impeded the nitrification. — William J. Robbins. 



996. Hills, T. J. Influence of nitrates on nitrogen assimilating bacteria. Tropic. Agri- 

 culturist 52 : 44-45. 1919. — Two lines of investigation, one on the influence of nitrate on azoto- 

 bacter and the other on the influence of nitrate on B. radicicola in the soil, were briefly sum- 

 marized without details of procedure. Full report given in Bull. Internat. Inst, of Agric, 

 Sept., 1918.— R. G. Wiggans. 



