SOILS FERTILIZEBS. 513 



Physical analyses of the soils showed a great variation in permeability. The 

 coarser silts showed the greatest permeability, but the silts held in suspension 

 in irrigation canals were almost impermeable. The air capacity decreased and the 

 moisture capacity increased with the density of the silt. 



Owing to the large amounts of silt carried in suspension by some of the 

 irrigation canals supplied by these streams, it is concluded that long-continued 

 irrigation with such water is capable of modifying quite considerably the 

 physical condition of soil by greatly increasing its content of fine particles and 

 its water capacity and causing it to become compact, impervious, and poorly 

 aerated. 



Soil productivity and agro-geological surveys, H. T. Ferrae (Jour. Canter- 

 bury Agr. and Past. Assoc, 3. ser., 3 (1915),. pp. 28-35). — This article briefly 

 outlines the development and economic value of soil surveys in this country, 

 Kgj'pt, Australia, and New Zealand. 



On the probable error of sampling in soil surveys, G. W. Robinson and 

 W. E. Lloyd (Jour. Agr. Sci. [England], 7 (1915), No. 2, pp. lU-153, figs. 2).— 

 Laboratory experiments with 25 samples from a field of glacial drift soil and 

 15 samples from a field of sedimentary soil are reported. The purpose was 

 to obtain values for the probable field error due to the normal variation in 

 the composition of the soil from point to point in a field. 



It was found " that an accuracy of 5 per cent in mechanical analysis is 

 insured a probability of 4 : 1 by doing a duplicate analysis on six borings. For 

 survey purposes this is probably sufiicient, since it is not conceivable that 

 variation in the amount of any fraction corresponding to 5 per cent (relative 

 to the amount of the fraction) could have any effect on the properties of a 

 soil. In the case of chemical analysis it does not seem that the same accuracy 

 can be expected. ... In the case of a critical study of one soil, however, 

 it would be necessary to reduce the errors much more by repeating analyses 

 and increasing the number of borings." 



A soil sampler for soil bacteriologists, H. A. Notes (Science, n. ser., 42 

 (1915), No. 1079, p. 317). — ^A sampler is described which, it is stated, will sample 

 the soil under one system of cultivation as well as another and which becomes 

 the soil container. It consists essentially of a brass tube 11 in. long with 

 a cutting edge at one end furnished with a tight-fitting 2-in. brass cap. The 

 open end is plugged with absorbent cotton. In using the sampler it is first 

 plugged and capped and sterilized by hot air. The cap is then removed in the 

 field and the sample taken by driving the sampler into the ground to the de- 

 sired depth, removing, flaming, and recapping. 



New methods in soil protozoology, N. Kopeloff, H. C. Lint, and D. A. 

 Coleman (Science, n. ser., 42 (1915), No. 1078, pp. 284-286) .—The substance of 

 this article has been previously noted from another source (E. S. R., 33, p. 809). 



Investigations on the distribution of Cyanophycese on and in different 

 soils, F. EsMARCH (Hedtvigia, 55 (1914), No. 4-5, pp. 224-273, figs. 5).— Inves- 

 tigations on the occurrence and distribution of Cyanophyceiie in from 35 to 45 

 samples of the surface soil of each of several different German soils when culti- 

 vated and uncultivated and in 129 samples of the subsoils of the same are 

 reported. 



The percentage of samples of each surface soil containing Cyanophycese were 

 as follows : Cultivated marsh soil, 95 per cent ; cultivated loam soil, 94.6 per 

 cent ; uncultivatetl moist sand soil, 88.6 per cent ; cultivated sand soil, 64.4 per 

 cent ; forest soil, 12.5 per cent ; sandy heather soil, 9 per cent ; and moor soil, 

 none. These results are taken to indicate that the occurrence and distribution 

 of Cyanophycese in the surface soil depend largely on the content of moisture 

 and of nutritive salts in the soil. 



