SOILS FERTILIZERS. 819 



Some problems in soil fertility, G. Severance (Washington Sta. Popular 

 Bui. 4h PP- S). — This is a brief, popular discussion of various factors influencing 

 the fertility of soils, with particular reference to Washington soils. 



A case of soil infertility due to bad texture and lack of lime, J. A. 

 Hanley (Jour. Bd. Agr. [London], 19 (h912), Xo. 5, pp. .37.5-378).— With a 

 view to determining the cause of the infertile condition of the soil of a portion 

 of a field near Luton, Bedfordshire, the author made physical analyses of the 

 soil and determined its calcium carbonate content. The results showed that the 

 infertile condition was due to the unfriable nature of the soil, caused by its low 

 calcium carbonate content, the samples analyzed containing 0.28 per cent of this 

 constituent in both surface and subsoil, as compared with 2 per cent for the 

 surface soil and 1 per cent for the subsoil of samples of the productive soil of 

 the field. 



Refei-ence is also made to analyses of samples of soil of the Geescroft field 

 at Kothamsted and of a similar soil at Ilamsey Green, Surrey, both of which 

 showed a low calcium carbonate content and were in a very poor state of tilth. 



Studies on soil physics. — II, The permeability of an ideal soil to air and 

 water, W. H. Geeen and G. A. Ampt (Jour. Agr. Bci., 5 (1912), No. 1, pp. 1-26, 

 pJ. 1, figs. 10). — The authors review previous investigations on the subject by 

 others, particularly the work of Slichter and of King (E. S. R., 11, pp. 510, 523), 

 and in continuation of earlier work (E. S. R., 25, p. 620) report measurements 

 of the permeability of glass beads and quartz sand to air and to water. An 

 elutriation method and apparatus for grading the particles are described. 



The permeabilities of the glass beads, both to air and water, were from 

 50 to 85 per cent greater than the value calculated from Slichter's formula. 

 This is held to be due to Slichter's method "of considering each soil capillary 

 as if it were a double triangular-shaped pore with a partition down the center 

 instead of as an undivided more or less rhomboidal pore at its narrowest part." 

 When this condition was fulfilled, the permeability of the glass beads ap- 

 proached the value calculated in the formula. 



The permeability of the sand, although subject to a rather large percentage 

 error, was on an average "9.45 for the permeability to air . . . and 9.31 for the 

 permeability to water. . . . The obvious explanation (of this less perfect ma- 

 terial agreeing more perfectly with thfe theoretical formula) is that the angular 

 shapes of the particles do practically have the effect of dividing the pore into 

 two triangular passages as assumed in the formula." 



tP 

 The general conclusion, therefore, is that '" the formula 7;P=10.2 ~ holds 



quantitatively for variations of the i)ore space and of the diameters of the 

 soil particles. This will be so whether the permeating fluid be air or water, 

 provided that the actual sizes of the soil particles are unaffected by the presence 

 of water. 



"With this factor taken into account it is, therefore, legitimate to consider a 

 soil as statistically composed of a bundle of capillary tubes when discussing the 

 movements of air and water through it." 



Observations on liquids circulating' in cultivated soils, G. Gola (Ann. R. 

 Accad. Agr. Torino, 5.) (1911), pp. 33-67. fig. 1). — This article has been noted 

 from another source (E. S. R., 26, p. 422). 



The movement of water in irrigated soils, J. A. Widtsoe end W. W. 

 McLaughlin (Utah Sta. Bui. 115, pp. 195-268, figs. S).— This is a detailed re- 

 port of a series of irrigation investigations conducted by the Utah Station in 

 cooperation with this Office, and reports a study of the mutual relationships of 

 water, soils, and crops under cropped field conditions, the work having been 

 partly reported upon in previous publications (E. S. R., 22, p. 425). The ex- 



