191P] SOILS — FERTILIZERS. 615 



in this a ratio as low as 1.2 or 1.3 appeared only under the severest drought con- 

 ditions. Tlie normal moisture condition in tlie deeper subsoil (6 to 20 ft.) ap- 

 peared to correspond to a ratio between 2 and 2.4. 



The dry condition of the deeper sub.soil so common in the semiarid praii'ies is 

 attributed to tlie presence of perennials witli a vertical-root range of 1-5 ft. or 

 more, while the moist condition characteristic of that of the liumid prairies is 

 regarded as evidence that the roots of the native vegetation are but little de- 

 veloped below tlie tiftli foot. The occurrence of areas in the semiarid prairies 

 even after a severe drought, in which tlie subsoil below the sixth foot is quite 

 moist, is attributed to the absence or fewness of deep-rooted perennials in such 

 places. 



Relation of soil moisture to orchard irrigation practice, S. Foktier {Mo. 

 Bui. Cal. Com. Hort., 8 (1919), No. 7, pp. 361-467).— The author presents data 

 based largely on the work of the Irrigation Investigations Division of the 

 Bureau of Public Roads, U. S. Department of Agriculture. 



He points out that " the great need of arid soils in general and of orchard 

 soils in particular is an abundant water supply and a larger percentage of or- 

 ganic matter. The effective water-holding capacities of soils should be deter- 

 mined in order to find out how much water to apply at each irrigation and 

 how often to irrigate. Comparatively little moisture is drawn upwards through 

 soils by capillarity. It is only where a water table is found within a few feet 

 of the surface or wliere a body of free water comes in contact with the soil that 

 this force is efficient in moving soil moisture. Gravity acts on capillary water as 

 well as free water, and draws both downward unless a layer of hardpan or 

 other impervious material intervenes. The expense of substituting the basin 

 method for the furrow method may be saved providing the texture of the soil 

 is improved by the addition of suflicient organic matter." 



Partial sterilization of soils and the influence of soil protozoa on their fer- 

 tility, G. TiiUFFAUT {Genie Rural 11919], No. 89-90, pp. 22-24).— The theory of 

 the partial sterilization of soils is discussed and a summary of experiments is 

 given, the apparent purpose being to place partial sterilization of soils on a 

 practical large-scale working basis. 



It w^as found in general that treatment of rich soils with carbon bisulphid at 

 the rate of 445 lbs. per acre resulted in increases of crops of cabbage and 

 onions of from 170 to 200 per cent. These tests were conducted on 5-aci-e 

 plats. The use of such carbonaceous aromatic liquids as benzine, toluene, 

 methylnapthalin, and anthracenic oils at the same rate produced crop increases 

 of from 125 to 145 per cent. When these materials were used it was necessary 

 to supply from 6 to 8 tons of water per acre. The use of carbonaceous solids 

 at the rate of 223 lbs. per acre resulted in increases of from 130 to 160 per cent 

 and were much more economical than the liquids. 



Further pot and plat experiments with turnips showed the value of pure 

 calcium sulphid when used at the rate of 445 lbs. per acre. However, decreases 

 were noted if the calcium sulphid contained such impurities as zinc sulphid. 



It is concluded in general that the partial sterilization of soils in both field 

 and orchard is feasible. 



Soils, W. A. Davis {Ann. Rpt. Bd. Sci. Advice India, 1916-17, pp. 5, 6).— Six 

 years' field experiments on the economical use and effect of certain fertilizers 

 on acid old alluvial soils of the Assam valley showed the paramount importance 

 of adding basic material, preferably lime. Complete fertilizer mixtures were 

 without effect unless the soil acidity was first neutralized. The necessary 

 degree of neutralization of soil acidity varietl with the crop and the soil. 



Next to lime, phosphoric acid was found to be the limiting fertility factor in 

 these soils. The best results were obtained from basic slag, rock phosphate, 



