SOILS FERTILIZERS. 221 



tute a fine sieve for the separation of fine silt and clay, as suggested by Lucas, 

 the author found an error of as much as 16 per cent. As a quick method of 

 obtaining useful information in many cases the author recommends that the 

 limit for clay be fixed at 0.01 mm. with a subsidence of 30 minutes in a column 

 of water 7i cm. high. 



The study of soils in Egypt, W. F. Hume (Resum§ 2, p. 4). — In this article 

 the author makes a plea for a systematic soil survey of Egypt and outlines a 

 plan for such survey. 



The First International Agrogeolog'ical Congress, E. J. Russell (Nature 

 [London], 84 (J910), No. 2121, pp. 151, i58).— This is a brief review of the 

 report of this conference held at Budapest in 1909, particular attention being 

 given to a paper by Glinka on Russian soils (E. S. R., 23, p. 316). 



The Mkatta plains, P. Vageler {Tropenpflanzer, Bcihefte, 11 {1910), No. 

 Ji-5, pp. 2Iil-395, pi. 1, figs. 11). — A general description of the Mkatta plains 

 of East Africa with special reference to the topography, hydrography, climatic 

 conditions, vegetation, and soil types is given, and the relationship between 

 the vegetation and different types of soils is discussed. The method of pro- 

 cedure and the apparatus used in the investigation are described. Full data 

 for climatic conditions, and physical and chemical analyses of each of 8 soil 

 types are reported, and the characteristic vegetation of the different types is 

 described. 



Special attention is called to the fact that very often vegetation changes its 

 characteristics under similar climatic conditions, such change being due to dif- 

 ferences in the character of the soil. The author traces a distinct relation of 

 the formation and the physical, but not the chemical, properties of soils to the 

 vegetation on virgin soils within a given climatic area. A district of similar cli- 

 matic conditions, particularly with regard to quantity and distribution of rain- 

 fall, producing a certain type of vegetation, will have a certain type of soil. 



By establishing definite soil types for the different climatic districts the 

 number of types will be considerably reduced, lessening the labor and cost of 

 soil investigation. 



The control of blowing soils, E. E. Free and J. M. Westgate (U. S. Dept. 

 Agr., Farmers' Bui. J/El, pp. 23, figs. 10).— -The authors discuss the normal move- 

 ments of the soil, the causes and control of soil blowing on sandy, newly 

 cleared, and other lands, and the control of drifting sand and sand dunes by 

 plants and mechanical devices. Other problems discussed are protection of 

 irrigation ditches, embankments, and roads, and the blowing of frost-loosened 

 and cutover soils. 



It is shown that the blowing of soils is of much importance in humid as well 

 as in dry regions and although the effects are in the main bad, benefit is some- 

 times derived from the process by the mixing Of soil particles and the renew- 

 ing of surface laj^ers. The most practical means of control consists of the use 

 of systems of cropping and tillage which will provide protection of each plant 

 or rough surface soil at critical stages and will keep the soil well stocked with 

 humus. 



On methods of bacteriolog'ical soil investigations, J. Vogel (Gentbl. Balct. 

 [etc.], 2. Abt., 21 {1910), No. 22-2.5, pp. 593-605, dgm. i).— The author claims 

 that in investigations on soil bacteriology the experiments should be performed, 

 not in solutions, as is usually done, but with the soils themselves, by which 

 method simplicity in operation and substantial agreement in parallel determina- 

 tions in the laboratory reactions and field experiments will result in the 

 majority of cases. 



The author illustrates the value of this method by a series of experiments 

 involving various soil bacteriological problems, such as the nitrifying energy 



