716 EXPERIMENT STATION RECORD. 



the geological survey in Natal and explains at some length the relation of 

 geological formations and conditions to the physical, chemical, and biological 

 character of the soil, water snpjily and drainage, and similar matt(M-s of agri- 

 cultural importance. 



Soils in relation to fertility, I. Cameron {RlKXlesian Agr. Jour., // {1901), 

 No. 5, pp. 'iSS-JfJ/'f). — This is a brief general descrii>tion of the arable soils of 

 Rhodesia and a discussion of their formation, composition, and adaptations. 

 Mechanical and chemical analyses are given of samples of a typical soil of the 

 region. 



On potash and phosphoric acid in cultivated soils of Java, T. Marr ( Meded. 

 ProefHiat. Oosi-Jara, J,, so:, 1901, No. 35, pp. 291-355, pis. 2).— The results of a 

 detailed study of the total and available potash (soluble in calciiun chlorid 

 and 2 per cent citric acid) and phosphoric acid (soluble in nitric, hydrochloric, 

 and 2 per cent citric acids) in a large number of ,T;ivan soils are reported in 

 detail in this article. 



Experiments on the availability of phosphates and potash in soils, J. W. 

 Leather {Mem. Dcpt. Agr. India, Chcm. ficr., / {19U1), No. //, pp. 1(3-51, pis. 

 //). — Determinations of available phosphoric acid and potash by the Dyer 

 method and pot tests with cereals during two years with 8 soils fi*om different 

 l>arts of India are reported, the autht)r concluding from the results obtained 

 that "there can not be any doubt that the fl)yer| method is itroving generally 

 useful for ordinary agricultural land, enjoying a rotation of croi)s. one of which 

 is usually a cereal, and that the limiting figure i)i'op(tsed by Dyer is nuich more 

 generally a])plicable than might have been expected." Dyer's limiting figures 

 are U.Ol per cent of potash and phosphoric acid soluble in 1 per cent citric acid, 

 i. e., soils containing less than this amount need phosi)li()ric acid and potash. 



Investigations on the moisture content of soils, W. Sciineidewind et al. 

 (Landir. Jnlirb., 3G {1901), No. If, pp. 5H2-'S5). — Deternunations of moisture 

 to a depth of 2."> cm. during the dry year 1005 and the wet year 1 !>()(;, in fallow, 

 fertilized, and unfertilized rotation i)lats, and green manure plats, are reported. 

 The soil water varied widely in the two years. The highest water content was 

 found in fiillow. The water sui)ply of the soil was exhausted to the greatest 

 extent by oats. Fertilizers by increasing the growth increased the draft on 

 the water supply of the soil, and green manui-e crojis ma<le a large draft on 

 soil moisture. 



Note on the movement of moisture in soils, W. .1. Humphreys {Srie)ice, n. 

 scr., 26 {1901), No. 661, pp. Jf80, ^,S/).— This is a brief note calling attention 

 to the important role which changes in surface tension due to changes in tem- 

 perature i>lay in the movement f»f soil moisture. The fact that the surface 

 tension of the soil moisture increases as its temperature is lowered accounts 

 for the more I'apid movement of moisture toward the surface of the soil during 

 the night than during the day. 



" Whenever the temperature falls very greatly the corresponding large 

 increase in the tension and in the condensation at the cold surface will take 

 much moisture from the warmer soil beneath. It is largely, if not wholly, this 

 that leads to wet soils so often seen on cold mornings when there has been no 

 rain, and to the surprising depth of mud that frequently follows a thaw. It 

 accounts, too, for the considerable supjily of moisture from the deeper soil in 

 the production of ice columns — spewing of the ground. 



" This temperature effect on surface tension, on condensation, and on evap- 

 oration also greatly conserves that moisture already in the earth and keeps it 

 in motion. That is, the moisture is brought to the surface in greatest abundance 

 only when the temperature there is low and therefore the rate of evaporation 

 into the air small, and whenever the surface temperature is increased, leading 



