SOILS FERTILIZERS. 51 7 



soluble in carbonated water than the healthy soils. The sick soils were made 

 healthy by adding small amounts of manganese or ammonium sulphates. The 

 humus of the sick soils was less soluble in ammonia than that of the healthy 

 soils, and its autoxidatiou was promoted by the alkaline reaction of the soil. 

 Aut oxidation may have exerted an injurious effect by (1) causing a deficiency 

 of oxygen in the soil atmosphere, (2) production of poisonous reduction pro- 

 ducts, or (3) formation of H2O2 and other peroxids. The beneficial effect of 

 manganese sulrihate is ascribed to its action in decomposing these peroxids. 



The applicability to India of the Italian method of utilizing silt, E. C. 

 Buck (Jour. »s'oc. Arts, 53 (1907), A'o. 28ft5, pp. 7Jy/-7.JJ).— The Italian methods 

 of warping and distributing muddy irrigation water so that the silt will be 

 deposited and enrich the soil are fully described and their applicability to 

 conditions in India are discussed. Cases of successful reclamation of rough 

 gullied land in India by means of dams, terraces, and drains, which check the 

 flow of the irrigation water and allow the silt to be deposited, are cited. 



The hygroscopic water of the soil and the underground dew, A. B. Speran- 

 SKi and T. N. Krasheninnikov (ZJiur. Opuitn. Agron. [Rus^. Jour. Expt. 

 Lanclw.], 8 (1907), No. 3, pp. 281-335) .—The authors report the results of ex- 

 periments which showed that when the surfaces of soils containing 33 and 23 

 per cent of moisture were heated more than 30 per cent of the water lost by 

 the upper layer of the soil passed as vapor into the lower layers and was there 

 condensed. It was found that soils whose surfaces were periodically heated 

 lost less water into the air than those not so heated. The greater the amplitude 

 of the temperature variations the more favorable the conditions for the forma- 

 tion of underground dew. 



The upper dried-out layer of soil apparently protected the lower layer from 

 loss of moisture, and when heated a part of the water of the upper layer passed 

 into the air and part into the lower layers of the soil. On cooling, the upper 

 soil layer absorbed moisture both from the subsoil and from the air. 



In the larger number of the experiments reported, the warming of the sur- 

 face of a soil of low-water content increased the transpiration from plants but 

 decreased evaporation from the surface of the soil. Thus, while the water was 

 in large part driven to the subsoil by heating the surface of the soil, it was 

 still available to plants, and the limited supply of soil moisture was better 

 utilized than when the surface was not alternately heated and cooled. 



The results of these experiments indicate an explanation of the deep rooting 

 and the drought resistance of plants on arid soils. 



Observations and calculations are given to show the amount of water which 

 will thus pass between the different soil layers under varying temperature and 

 moisture in order to maintain the equilibrium of vapor pressure throughout the 

 soil. 



Observations on temperature variations in soil, Grohmann {Fiihliiig's 

 Lanihr. Ztg., 56 (1907), Xo. 8, pp. 273-281.)— The heat capacity of various min- 

 eral constituents of soils is discussetl and studies of the temperature condi- 

 tions at different depths (0.1 to 0.5 meter) in various typical soils, as well as 

 in air and water subjected to heat rays of 2 ton-calories for 1, 4, and 9 hours, 

 are recorded. 



It is shown that the heat relations of soils are dependent upon their proper- 

 ties and moisture conditions, and the conclusion is reached that the temperature 

 vaTiations may be calculated when the amount of sunshine is known. 



A review of investigations in soil bacteriology, E. B. Voouhees and J. G. 

 LiPMAN {(I. tS'. Dipt. Atir., Office E.rpt. Stas. Bill. 19.'/. pp. 108). — This review 

 attempts to summarize the more important results of investigations on this sub- 



