Steam Sterilization on Water-Soluble Matter in Soils, 249 



Hasenbaumer, Coppenrath, and Konig' heated 250 grams of soil with 

 3 to 4 Hters water for three hours, 4 atmospheres pressure, and state 

 that the solubihty of the mineral constituents was increased by the 

 treatment. 



Koch and Liiken- found that the soluble plant food in the soil was 

 increased and that the crops were improved when a sandy soil was heated 

 with steam at 2 atmospheres pressure for two hours. Although the soils 

 received applications of fertilizers in each case, the heating produced 

 immediate injurious effects, though these were found to be unimportant 

 if the plants were started in summer instead of in early spring. 



Darbishire and RusselP heated soil with steam to 90° or 95° C. An 

 increased crop was obtained with plants other than legumes, and this 

 effect extended to a second crop. 



Pickering* heated soil to 82° C and to 200° C and grew two-year-old 

 apple trees in the soil. The growth at first was very poor, but later 

 became very vigorous. The soil heated to the higher temperature gave 

 the greater growth of wood and leaves and the leaves contained a higher 

 percentage of nitrogen. 



Chemical analyses of the aqueous extract showed an increase in the 

 organic matter and nitrogenous substances especially when the soil was 

 high in moisture content at the time of heating. Konig, Hasenbaumer 

 and Grossman^ attempted to correlate the fertility of soils with the 

 effects produced in them by steaming under pressure of five atmos- 

 pheres. From their results they concluded that the more easily and 

 largely the organic matter decomposes under this treatment, the more 

 easily and extensively the plant food of the soil becomes available to 

 plants. 



Schmoeger^ found that steaming moor soils for 10 hours at 150° to 

 160° C rendered the phosphorus more soluble in hydrochloric acid than 

 that in the soil not so treated. 



Russell and Hutchinson^ in working with soil heated to 98° C found 

 that while ammonia was formed by the process of heating, a much 

 greater production followed for at least 150 days afterwards. This they 

 attribute to the increased number of ammonifying bacteria in the heated 

 soil, the multiplication of which is made possible through the destruc- 

 tion by heat of the larger organisms which normally limit ammonification 



^Landw. Versuchs. Stat. 63 (1906) p. 471 

 ^Jmir. f. Lanrlw. 55 (1907) p. 161 

 ^Jour. Agr. Sci. 2 (Dec. 1907) p. 305. 

 ••Jour. Agr. Sci. 2 (July, 1908) p. 411. 

 ^Landw. Versuchs. Stat. 69 (1908) t-qt. 

 'Bcrichte d. Deutschen Cliem. Gesell, 26 p. 386. 

 ^Jour. Agr. Sci. vol. 3, p. m. 



