118 EXPERIMENT STATION RECORD. [Vol.37 



" Employing 2-ft. columns of 12 different loams, each with an initial moisture 

 content approximately equal to its hygroscopic coefficient, enough water was 

 added to raise the average moisture content of the column to 1.5 times the 

 hygroscopic coefficient, the water being applied in one experiment to the top 

 and in another to the base of the column. After the cylinders had stood for 

 three or four months fully protected from evaporation the distribution of 

 moisture, with regard to the surface to which it had been applied, was found 

 to be the same in both experiments. The maximum distance through which 

 an effect was shown was about 2 ft., but in most cases much less. The maxi- 

 mum final ratio of moisture content to hygroscopic coefficient was found in 

 the section adjacent to the surface of application, where it lay between 1.7 

 and 2.4. The ratio, while falling within these limits, is not a constant. It 

 not being the same for all the soils that have the same hygroscopic coefficient. 



" The water-retaining capacity of the loams, as determined by laboratory 

 experiments, was found to bear a somewhat closer relation to the moisture 

 equivalent than to the hygroscopic coefficient, the ratio varying between 0.8 

 and 1.2. 



" Coarse sands exhibited a behavior very different from that of the loams. 

 The ratio In the surface 6-in. section, even three months after 1 in. of water 

 had been applied to the surface, was as high as G or 7, while in the second foot 

 it was only 1. The field studies on coarse sands showed as high a final ratio 

 as was obsorvod in the hiljoratory experiments. Tlie very limited studies on 

 fine sands indicate that these occupy a position Intermetllate between the loams 

 and the coarse sands, the ratio of the water-retaining capacity to the hygro- 

 scopic coefficient rising as the latter value falls. 



" Field studies show that when loams, after rains sufficiently heavy to 

 moisten them thoroughly, are protected from lo.sses by evaporation and trans- 

 piration, they lose water by downward movement until the ratio of moisture 

 content to hygroscopic coefficient lies between 1.8 and about 2.5, and accord- 

 ingly on the uplands of dry-land regions this is the ratio to be expected in the 

 deeper subsoil — the portion below the range of plant roots. 



"A comparatively abrupt transition from the moistened soil to the thoroughly 

 exhausted underlying layers, with ratios of 2:2.5 and 1:1.1. respectively, is 

 found even several months after liberal rains have fallen, if the subsoil to a 

 considerable depth had previously lieen exhausted of avaihible water. The 

 moisture of the deeper subsoil will be able to move upward only so slowly and 

 through such a short distance in a single season that it will be at most of 

 no practical benefit to annual crops. To make use of any portion of the pre- 

 cipitation which penetrates beyond the reach of the roots of annual crops it 

 will be necessary to follow such crops at intervals by deep-rooting perennials." 



Twenty-five references to literature bearing on the subject are appende<l. 



Investigations on the acidity of acid mineral soils, I. S. Osugi and T. 

 UET.srici {Bcr. Ohnrn Inst. Lnudir. Forsrh., 1 (1916), Xo. 1, pp. 27-52, fig. 1).— 

 On the assumption that the acidity of acid soils is intimately related to their 

 alumina content, the authors conducted experiments In which it was found 

 that when the bases of soils di';;\ppear as a result of active weathering and 

 decomposition certain colloidal substances are formed in the soils which 

 actively absorb bases. When such soils are then treated with salt solutions 

 acids are set free. It was found that the alumina in .soils is easily dissolved 

 out by hydrochloric acid but not by acetic acid. Therefore, coniderable alumina 

 was found in the filtrate of a potassium chlorid solution of the soil but only a 

 little in the filtrate of a potassium acetate solution of the soil. It is thought 

 that other factors also iuflueuce the difference in the intensity of the acidity 



