SOILS FERTILIZERS. 619 



The types are quite similar in the two areas, although as a result of the 

 greater rainfall and somewhat different character of the formations in the 

 northern rivers regions the soils of this area have been leached out to a greater 

 extent. TTevertheless, the soils of this area are much more productive than 

 those of the Manning-Macleay district. 



An average of 294 analyses of North Coast soils shows nitrogen 0.256, phos- 

 phoric acid 0.178, potash 0.086, and lime 0.173 per cent. The soils vary In 

 composition with the formations from which they are derived. The forma- 

 tions yielding very poor soils are the sandstones and quartz schists, those 

 giving medium class soils are the granites, shales, and slates, and those giving 

 good soils are the limestone, basalt, and alluvial formations. The limestone 

 soils are as a rule of fine quality, and the volcanic soils are very fertile. The 

 serpentine soils, however, are not so fertile as their chemical composition 

 would indicate. The unproductiveness of certain of the soils is attributed 

 to the presence of unusual amounts of manganese and magnesia. 



The soils are mapped with reference to relative productiveness. 



The chemical nature of the black-soil plains, F. B. Gutheie and H. I. 

 Jensen (Agr. Gas. N. S. Wales, 21 (1910), No. 10, pp. 855-860).— It has been 

 suggested that these black soils, occurring in the northwestern part of New 

 South Wales, are of volcanic origin, but the authors are of the opinion that 

 they are of alluvial origin. They include some of the richest grazing lands 

 of the State, and a study of their chemical and physical properties shows 

 that they are as a rule stiff clay soils of low capillary power and highly 

 retentive of Y\'ater, becoming very sticky when wet and very hard and cracked 

 when dry. They are not rich in organic matter and are invariably low in 

 nitrogen, but they are rich in mineral plant food, particularly lime and potash. 

 The soils are usually slightly alkaline in nature. 



The average percentage of nitrogen in 10 samples of these soils was 0.089, 

 phosphoric acid 0.179, potash O.o37, and lime 0.666. The volatile matter amounted 

 to 7.4 per cent, and water to 6.7 per cent. Four physiographic classes of black 

 soils are described. 



The relation of vegetation to water extracts from the soils of Atbasar 

 District, Akmolinsk, G. Tumin {Zliitr. Opijtn. Agron. (Riiss. Jour. Expt. 

 Landw.). 11 {1910), No. 5, pp. 70.'/-7'iS). — Water extracts from different depths 

 of soils were analyzed to determine the percentages of dry matter, chlorin, sul- 

 phuric acid, and alkalinity in a region the annual rainfall of which is 200 mm. 



The data obtained show that the concentration of the soil extract varied for 

 the different depths of soil. Plants endured a higher degree of concentration 

 of soil solution in the deeper layers of soil than in the surface soil. Not only 

 calcium sulphate but also calcium carbonate enabled the plants to endure 

 stronger concentrations of soil solutions. At the same time the author does 

 not believe that the greater resistance of plants to concentration of solutions in 

 the deeper layers of soil is dependent alone upon the amounts of calcium sul- 

 phate and calcium carbonate present in such layers of soil, but that the plants 

 themselves play an important part in this respect. 



Physical and chemical pi'ocesses in soil formation in the Tropics, P. 

 Vageleb (FiihUng's Landw. Ztg., 59 (1910), No. 24, PP- 873-880; abs. m Chem. 

 Ztg., 34 (1910), No. Ill,, pp. 1014, 1015). — This is a paper presented at the meet- 

 ing of German Naturalists and Physicians at Konigsberg. 



It is stated that laterite or, more properly, red soils are typical of the 

 Tropics. These soils are as a rule poor in plant food. A'arious hypotheses haA-e 

 been advanced as to the mode of formation of these soils, but the author 

 attempts an explanation from the standpoint of colloid chemistry. The princi- 

 pal colloids involved in the process of formation are silicic acid, iron oxid, and 



