SOILS — FERTILIZERS. 221 



has been a large factor in increasing agricultural production In tliat country. 

 In fact, 50 per cent of the increase, which has been very pronounced, is at- 

 tributed to the rational use of fertilizers. 



Bone products and manures, T. Lambert (London, 191S, 2. rev. ed., pp. y//+ 

 167, figs. J7).— This is a second revised edition of this work (E. S. R., 13, p. 634). 



The solubility of soil constituents, H. Fischer (Internat. Mitt. Bodenk., 3 

 (1913), No. 4, pp. 331-337, fig. 1). — In a comparison of the solubility of phono- 

 lite and biotite in water saturated with carbon dioxid according to the Islit- 

 scherlich method it was found that the potash of the latter was less soluble 

 than that of the former. This, however, is not in accord with results of crop 

 tests by other investigators which showed that the potash of biotite is more 

 readily assimilated by oats than that of phonolite. Methods of rendering the 

 potash of phonolite more assimilable by plants are briefly discussed. 



Comparative manuring experiments with crushed phonolite and 40 per 

 cent potash salts, F. Wagner (Prakt. Bl. Pflanzenbau u. Schutz, n.- ser., 11 

 (1913), Nos. 4, pp. 52. 53; 5, pp. 67-70; 6, pp. 77-82, fig. 1; ahs. in Internat. 

 Inst. Agr. [Rome], Mo. Bui. Agr. Intel, and Plant Diseases, 4 (1913), No. 10, 

 pp. 153Ii, 1535). — Ground phonolite was compared with 40 per cent potash salt 

 on hops grown on soils poor in potash. The phonolite was used in connection 

 with a basal fertilizer of ammonium sulphate, Thomas slag, and lime, but the 

 results from its use were in no way comparable with those obtained with the 

 potash salt. 



The possibility of replacing Stassfurt potash salts by finely ground phono- 

 lite, leucite, etc., Lemmermann (Internat. Inst. Agr. [Romel, Mo. Bui. Agr. 

 Intel, and Plant Diseases, 4 (1913), No. 10, pp. i4SS-i//95).— Experiments with 

 various natural silicates of potash are reviewed. 



It is shown that the fertilizing effect of these is variable, but generally low. 

 They are not comparable with potash salts. Various processes which have been 

 proposed for the improvement of their assimilability are noted, but it is held 

 that none of them offers a practical substitute for the German potash salts. 



Influence of the condition of the soil on the utilization of different phos- 

 phates, H. R. Christensen (FiiliUng's Landw. Ztg., 62 (1913), No. 11, pp. 392- 

 405). — Experiments are reported which were conducted to determine the rela- 

 tive values of superphosphate, Thomas slag, bone meal, and Algerian phos- 

 phate fertilizers under varying conditions of cultivated and meadow soils, the 

 variable factors being the power of the soils to set free acids, especially phos- 

 phoric acid, the moisture content, and the basicity. 



On cultivated soils the effects of the superphosphate and Thomas slag were 

 uniformly good, and both were utilized in practically the same quantities in 

 acid and basic soils, the Thomas slag being utilized slightly the more. Using 

 superphosphate as a standard, the results with bone meal and Algerian phos- 

 phate were poor. With a single exception it was found that the utilization of 

 the phosphoric acid of bone meal as compared with that of superphosphate 

 was very small in basic soils, while in nonbasic and acid soils the two were 

 utilized to about the same extent. No definite relations were found to exist 

 between the acid separating powers of cultivated soils and the utilization of 

 the four phosphates. 



In meadow soils superphosphate was utilized to a somewhat greater extent 

 than Thomas slag, the utilization of Thomas slag being greatest in the basic 

 soils. Bone meal, with one exception, was not utilized so well as superphos- 

 phate. Better utilization of bone meal was found on moist than on dry soils 

 with greater acid separating powers. The effect of basicity on bone meal was 

 not so marked as in the cultivated soils. 



