432 



Organic matter 



Moisture 



Lime 



Potash 



Phosphoric acid 



Nitrogen.. 



It is seen that bat guano number 2151 has a composition far below the average composition 

 of the soils in plant food constituents, while No. 1472 is far above that of the average soil. 

 In analyzing the bat guanos the author found the maximum amount of P2O5 to be 17.47 per 

 cent, for K 2 11.45 per cent, for N 9.63 per cent, and a minimum for P 2 Os of 0.02 percent, 

 K 2 trace and nitrogen 0.00 per cent. The average composition of fresh bat guano was 

 found to contain P2O5 5.67 per cent, K 2 1.37 per cent, and N 5.65 per cent. Of 103 samples 

 of bat guano the author classed 28 as nitrogenous, 33 as phosphatic, 8 as balanced, and 34 

 as worthless. — F. M. Scherlz. 



FERTILITY STUDIES 



2943. Anonymous. [Rev. of: Hoagland, D. R. The freezing point method as an index 

 of variations in the soil solution due to season and crop growth. Jour. Agric. Res. 12: 369-395. 

 1918.] Jour. Ecol. 7:95. 1919. 



2944. Anonymous. [Rev. of: Howard, A. Recent investigations on soil aeration, Part 

 I, with special reference to agriculture. Indian Forester 1918: 187-202. 1918.] Jour. Ecol. 

 7: 89-91. 1919. — The author presents data upon the decrease of oxygen and the increase of 

 carbon-dioxide in the soil atmosphere after heavy manuring or when there is a surface 

 accumulation of water. In irrigated soils in Northern India the crops often show symp- 

 toms of poor soil aeration leading to a decrease in yield. — Geo. D. Fuller. 



2945. Jennings, David S. Effect of certain colloidal substances on the growth of wheat 

 seedlings. Soil Sci. 7:201-215. 1919. — Agar added to nutrient solutions increases the 

 growth of wheat seedlings in low concentrations but decreases the growth in higher con- 

 centrations of nutrient solutions. The introduction of colloidal silicon into nutrient solutions 

 results in increased weight of wheat seedlings due to the direct absorption of the silicon by 

 the plant. The introduction of quartz, ferric hydroxide, and aluminum hydroxide into 

 nutrient solutions results in decreased growth of wheat seedlings due to the fact that their 

 absorptive power reduces the effective concentration of the nutrient solution. — William J. 

 Robbins. 



2946. Lyon, T. L. Experiments in fertilizing a crop rotation. New York Agric. Exp. Sta. 

 [Cornell] Bull. 399: 19-30. Feb., 1919. — In a rotation consisting of 3 years in hay, followed 

 by maize, oats and wheat, more profitable results were obtained when the fertilizer was ap- 

 plied each year to the timothy than when it was applied to the other crops. — W. O. Gloyer. 



2947. McMiller, Paul R. Some notes on the cause of the unproductivity of "raw soils" 

 in humid regions. Soil Sci. 7:233-236. 1919. — Some Minnesota subsoils are as productive 

 toward alfalfa when inoculated as are the corresponding surface soils, while others are much 

 leas productive. The application of soluble potash and phosphoric acid fertilizers renders 

 these subsoils as productive as the corresponding surface soils. — William J. Robbins. 



2918. Millar, C. E. Comparative rate of formation of soluble material in cropped and 

 virgin soils as measured by the freezing-point method. Soil Sci. 7:253-257. 1919. — Virgin 

 and cropped samples of 6 soils were washed with distilled water until practically all of the 

 soruble material was removed as indicated by the freezing point method. The moist soils 

 were then incubated at 25°C. and the amount of soluble material which formed determined 



