No. 3, April, 1921] SOIL SCIENCE 319 



2180. Weston, Robert Spurr. By-products from sewage sludge. Amer. Jour. Public 

 Health 10: 405-409. 1920. — A discussion of the treatment of sewage from the standpoint of 

 recovering by-products — chiefly fats and fertilizing materials. The Miles process is said to 

 give the best study for such recovery. The claim is made "that many American sewages 

 contain enough fats and fertilizer constituents to make the problem worth consideration." 

 Additional experiments necessary to put the recovery on a profitable basis are suggested.— 

 C. A. Ludwig. 



INFLUENCE OF BIOLOGICAL AGENTS 



2181. Greaves, J. E., and E. G. Carter. Influence of moisture on the bacterial activi- 

 ties of the soil. Soil Sci. 10: 361-386. Jt fig. 1920.— The ammonification, nitrification, and 

 nitrogen fixation of 22 soils at varying moisture contents were determined. The soils varied 

 from a loose sand to a tight clay, from soils with little or no organic matter to soils high in 

 organic matter. The moisture-holding capacities varied from 31 to 78 per cent. Every 

 soil gave a maximum ammonification at a water content of 60 per cent of the moisture-hold- 

 ing capacity. Maximum nitrification occurred at 50-60 per cent. Nitrogen fixation in many 

 soils showed two maxima, one at 50-60 and another at 70-80 per cent. Equations for the 

 optimum water content for bacterial activities are given based on the formulae of Briggs 

 for moisture equivalent, wilting coeflBcient, and hygroscopic coefficient. — W. J. Robbins. 



2182. Hodgson, R. W. Conservation in the use of manure. Monthly Bull. Dept. Agric. 

 California 8:512-517. 1919.— Considerable loss of manure results through aerobic decay 

 and fermentation both in the stable and in the orchard while in piles prior to distribution; 

 50-75 per cent of the nitrogen is lost. Urine should not be allowed to drain away. It seems 

 desirable to plough down manure rather deeply, 12 to 15 inches, so that it lies in the vicinity of 

 the feeding roots and undisturbed by constant cultivation. At that depth manure is unaf- 

 fected by atmospheric conditions and has optimum conditions for transformation into available 

 plant food. — E. L. Overholscr. 



2183. JosHi, N. V. Studies in biochemical decomposition of cow-dung and urine in soils. 

 Agric. Jour. India 15:398-409. 1920.— Non-nitrogenous manures (such as cellulose) lower 

 the amounts of nitrates formed from organic manures. Urine gives the greatest amount of 

 nitrates and nitrifies at once while cow-dung does not nitrify when fresh. Storage of sheep- 

 dung and urine in a pit is not desirable because of nitrogen losses. CO2 production and 

 nitrification are not necessarily correlated. — F. M. Schertz. 



2184. Russell, E. J. The partial sterilization of soils. Jour. Roy. Hort. Soc. 45:237- 

 246. 1919. — Tests of toluene, carbon bisulfide, carbolic acid, and formaldehyde as soil ster- 

 ilizers in comparison with heating are reported, and a general discussion of soil protozoa is 

 given. — J. K. Shaw. 



FERTILITY STUDIES 



2185. McFadzean, G. S. Top dressing pasture lands. Jour. Dept. Agric. Victoria 18: 

 408-412. 4 fig. 1920.— Good results were secured by top dressing with superphosphate and 

 bone meal in the Portland District. Clover and rye grass, the native grasses, have improved 

 with the use of fertilizers and the pastures support a larger number of cattle. — /. /. Skinner. 



2186. NoRRis, R. V. The exhaustion of Indian soils and the methods by which this may 

 be remedied. Agric. Jour. India 15: 433-443. 1920.— Attention is called to the use of manu- 

 rial substances which are now exported but may be used to a greater advantage at home. — 

 F. M. Schertz. 



2187. Rae, F. G. Electro-culture. Jour. Dept. Agric. Victoria 18: 385-394. 1920.— A 

 review of experiments showing the effect of electric currents in soil on the growth of plants. 

 The experiments cited show generally an increase. — /. /. Skinner. 



