EXPERIMENT STATION RECORD. 



Vol. XXIV. Abstract Number. No. 4. 



RECENT WORK IN AGRICULTURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Studies of the changes occurring in heated soils, S. TJ. Pickering (Jour, 

 Agr. ScL. 3 {1910), No. 3, pp. 258-276, charts 5).— "The water extracts ob- 

 tainable from soils are of constant composition as regards organic matter when 

 the time allowed for the extraction varies from 20 to 320 minutes, the tempera- 

 ture from 7 to 23°. and the proportions from 5 to 10 of soil to 100 of water. 

 The inorganic matter is not affected by the time, but is by the temperature and 

 proportions. 



" The increase in soluble matter produced by heating a soil, and the accom- 

 panying toxic qualities toward the germination of seeds in it, is gradually 

 reduced by exposing these soils in a moist condition to the air, even under 

 aseptic conditions, but is not reduced when the soils are kept moist in the 

 absence of air. The destruction of the toxic substance is probably, therefore, 

 due to oxidation. 



" Unheated soils, or soils heated only to a low temperature, exhibit on keep- 

 ing an increase in soluble matter ; this occurs whether air is admitted or not, 

 and this change, therefore, is probably not an oxidation process; the substance 

 formed, moreover, in such cases appears to have little or no toxic action on 

 germination. This increase of soluble matter, due to the formation of a non- 

 toxic substance, is preceded by a preliminary diminution of soluble matter, 

 precisely similar to the diminution of toxic matter occurring continuously in 

 the more highly heated soils; such toxic matter, therefore, appears to be 

 present in all soils, whether heated or not, though, in the latter case, it is 

 present in such small quantities that it soon becomes completely oxidized. 



" Air-dried soils, heated and unheated, when kept for some months show an 

 appreciable retluction in soluble constituents, and also in toxic properties (where 

 such properties were originally present), closely similar to the reduction 

 exhibited by moist soils kept in air for about 10 days." 



Chemical nature of soil organic matter, O. Schreiner and E. C. Shorey 

 {U. 8. Dept. Agr., Bur. Soils Bui. 74, pp. 48, pi. i).— The authors herein report 

 the results of investigations of numerous soils, from which they have isolated 

 16 definite organic compounds which " belong to 8 different classes of chemical 

 compounds, some containing carbon and hydrogen only, some containing carbon, 

 hydrogen, and oxygen, and some containing carbon, hydrogen, oxygen, and 

 nitrogen. Paraffin hydrocarbons, acids, alcohols, esters, carbohydrates, hexone 

 bases, pyrimidiu derivatives, and puriu bases are represented. The list of 

 isolated and identified compounds comprises: Hentriacontane, C3iHe4; mono- 



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