SOILS PEETILIZERS. 119 



proper measures in the cultivation of these moors are pointed out briefly as 

 potash and phosphoric acid fertilization, applied in the spring, liming, fall 

 plowing, sufficient but not excessive tile drainage, and green manuring. 



The fertility map of the Delta, B. F. E. Keeling {Cairo Sci. Jour., 8 (1914), 

 No. 88, pp. 1-3). — A brief description is given of the survey of the Delta of the 

 Nile, with reference to the agricultural value of the lands, which is now in 

 progress. The lands are being classified as good, medium, bad, uncultivated, 

 and under reclamation. The agricultural value of the lands is determined to a 

 large extent by the amount of alkali they contain. 



Soils, H. J. ViPOND (Union So. Africa Dcpt. Agr. Rept. 1912-13, pp. 297- 

 304)- — The results of chemical analyses of a number of samples of soils from 

 different parts of South Africa are similar to those previously noted (E. S. R., 

 29, p. 514), the average percentage of nitrogen being fair, and of lime and 

 available phosphoric acid very low, and the only noteworthy difference being 

 an increase in total and available potash. 



Analyses of ten samples of alkaline soils showed the presence of considerable 

 amounts of sodium carbonate and bicarbonate, and a smaller amount of sodium 

 chlorid. 



Laterite, its consideration in the light of colloid chemistry, A. Ltjz (Kol- 

 loid Ztschr., 14, {1914), No. 2, pp. 81-90). — The author briefly reviews a number 

 of opinions regarding the origin, formation, and composition of laterite, show- 

 ing the variation and development in these views during the past century. The 

 more recent general opinion is that laterite is a product of advanced weathering 

 of materials containing crystalline aluminum silicates which, in the process of 

 laterization, have l)een ti'ansformed by degrees into complexes containing, first, 

 colloidal aluminum silicates and colloidal iron hydroxid ; second, colloidal 

 aluminum hydroxid, colloidal silica, and colloidal iron hydroxid; and, third, 

 crystalline aluminum hydroxid, colloidal silica, and crystalline limonite. 



Critical remarks on the determination of the adsorptive power of the soil, 

 T. Oryng (Kolloid Ztschr., 14 {1914), No. 2, pp. 105-108).— In connection with 

 other criticisms of views regarding colloid chemistry the author points out the 

 narrow limits within which the colorimetric method is of value for determining 

 the adsorptive surfaces and power of soils. 



The influence of irrigation and crop production on soil nitrification, I. G. 

 McBeth and N. R. Smith {Ccntbl. Bakt. [etc.], 2. AM., 40 {1914), No. 1-8, 

 pp. 24-51, figs. 6). — This is an account of investigations, carried on in coopera- 

 tion between the Bureau of Plant Industry of this Department and the Utah 

 Experiment Station, which were made with soils of the irrigated experiment 

 farm of the station. The results are summarized as follows : 



" The application of irrigation water reduced the nitrifying power of the 

 soils as determined by laboratory methods. 



" The plats continuously cropped to alfalfa, potatoes, oats, and corn all 

 showed a higher nitrifying power than the corresponding fallow plats. The 

 stimulating effect of crop production on the nitrifying power of the soils was 

 most marked in the alfalfa land. 



" The nitrifying power of the soils was very weak below the second-foot zone, 

 and almost no increase in nitrates was secured below the fifth-foot zone. 

 About 90 per cent of the nitrate formed in the first 5 ft. was produced in the 

 upper 18 in. The application of irrigation water did not change the relative 

 nitrifying power of the different foot sections. 



" The moisture content of the nonirrigated plats during the summer months 

 fell far below the quantity required for active nitrification. No increase in 

 nitric nitrogen took place when the soil samjjles contained as little as 5 per 

 cent of moisture. 



