1 



210 EXPERIMENT STATION RECORD. [Vot. 43 



The water economy of soil in relation to pryper cultivation, choice of 

 crop rotation with reference to shading, and the influence of deep rooting 

 crops, R. TucH {Jahrb. Deut. Landio. OeselL, SJf {1919), No. 2, pp. 376-384).— 

 A general discussion of soil water as affected by various factors, particularly 

 cultivation and crops under German conditions, is given. 



The influence of variations of ground-water level due to canals and 

 mines on the utilization of soil for agriculture and forestry, Koeiine 

 {Jahrb. Deut. Landw. Gesell, 8/, {1919), No. 2, pp. 31,2-SlJ,, figs. 20).— Following 

 an introduction covering the general features of the subject by Scburig, a report 

 is given by the author on studies conducted in Germany in different localities of 

 the effects of mines, canals, water works, and other Industries on the water 

 level in agricultural and garden soils. It Is shown that these industries have a 

 varying effect, depending upon their size and attending geologic circumstances. 

 Considerable graphic data obtained from such studies ai-e given, together with 

 a description of the methods of study and precautions to be tal^en. 



The moisture equivalent in relation to tlie mechanical analysis of soils, 

 H. E. MiDDLETON {Soil ScL, 9 {1920), No. 2, pp. 159-167, fig. i).— Experiments 

 conducted by the Bureau of Soils of the U. S. Department of Agriculture are 

 reported, which showed that the moisture equivalent may not be used as a 

 basis for the classification of soils, but may be of valuable assistance in the 

 interpretation of the mechanical analysis. There is a direct relationship be-' 

 tween the moisture equivalent and the percentages of sand, silt, and clay in 

 the soil, as determined by mechanical analysis. This relation may be expressed 

 as 0.063 sand + 0.291 silt + 0.426 clay = moisture equivalent. The presence of 

 considerable amounts of organic matter in the soil tends to increase the moisture 

 equivalent and to disturb the relation between the moisture equivalent and the 

 mechanical analysis. 



A new soil elutriator, W. Gardner {Soil Sci., 9 {1920), No. S, pp. 191-195, 

 figs. 2). — A new soil elutriator developed at the Utah Experiment Station is de- 

 scribed and illustrated and its theory of operation discussed. The nature of the 

 process involved is such that a steady stream of muddy water is introduced 

 at the bottom of the smallest of a series of 19 cylindrical vessels, ranging iu 

 diameter in arithmetical progression from 4 to 40 cm. The stream leaves the 

 first cylinder through a conical cap, entering the second through a conical base 

 and so on throughout the series. 



Sampling soil plats, F. E. Bear and G. M. McClure {Soil ScL, 9 {1920), No 

 1, pp. 65-75, figs. 4)- — In a contribution from the Ohio State University, an ex- 

 periment is reported to determine how to choose a composite which would accu' 

 rately represent a plat for the particular day on which it was chosen. 



Two plats of ground, each -j^^ acre in size, were set aside for this test. Pla 

 1 was as uniform as could be secured on the experimental field, and plat 2 was 

 chosen for its lack of uniformity. On the basis of this study it is concluded tc 

 be desirable to locate the samples of soil, for the composite representing eacl 

 plat, uniformly over the plat. There appears to be no argument in favor o: 

 selecting separate samples of the surface and subsurface soil, but it is desirablt 

 that all samples be taken to a depth well beyond the plow line. According to thi 

 plan recommended the composite from each ^^-acre plat would be made up o 

 20 samples, each chosen to a depth of 12 in. and arranged uniformly over th 

 plat. In all subsequent samplings of these plats the location of the samples an( 

 the method of taking them should be as nearly an exact duplication of the firs 

 sampling as possible. 



The influence of sand upon the concentration and reaction of a nutrien 

 solution for plants, J. W. Shive {Soil Sci., 9 {1920), No. 3, pp. 169-179).- 



