8 ORGANIC CONSTITUENTS OF SOILS. 



The Bureau of Soils has undertaken its work from a new view- 

 point and has achieved some important results which throw much 

 light upon the dark subject of the cause of fertility and infertility 

 of our agricultural lands. I am very glad of this opportunity to 

 present to you the results of a phase of this investigation, namely, 

 the importance of the organic constituents of soils. 



I have brought with me a tangible result of this work in the form 

 of specimens of the organic compounds which have been found in 

 soils. Their isolation and identification give definite information 

 about a portion, and a very important portion, of the soil, the value 

 of which has been recognized in practice, but about which no definite 

 information was at hand until this work was undertaken. By the 

 application of modern methods of research to the intricate problems 

 of the soil we have been able to throw such light upon the biochemical 

 changes in soils that the old views of soil organic matter, soil humus, 

 and the process of humification are entirely overthrown. The 

 compounds of which Mulder, the contemporary of Liebig, writes, 

 such as humic acid, geic acid, ulmic acid, etc., terms which have 

 appeared in textbooks ever since, have absolutely no existence, but 

 are shown to be mixtures of many different, and widely different, 

 compounds. Not only were the compounds contained in these 

 specimen tubes not known as soil constituents to Mulder or Liebig, 

 but they were compounds unknown to the science of the time. With 

 the advance of science, especially of biochemistry, since that time 

 results such as these have been made possible. Some of these com- 

 pounds contain only carbon and hydrogen; some carbon, hydrogen, 

 and oxygen; some carbon, hydrogen, oxygen, and nitrogen; and 

 some carbon, hydrogen, oxygen, nitrogen, and phosphorus. The 

 compounds represent a great variety of chemical classes; there are 

 paraffin hydrocarbons, hydroxy fatty acids, and other organic acids, 

 esters and alcohols, carbohydrates, hexone bases, pyrimidine de- 

 rivatives, purine bases, and pyridine derivatives. The individual 

 compounds isolated or found are as follows : 



ORGANIC COMPOUNDS ISOLATED FROM SOILS AND IDENTIFIED. 



Agroceric acid. 



Agrosterol. 



Arghi ine. 



Creatinine. 



Cytosine. 



Dihydroxystearic acid. 



Glycerides, liquid. 



Hentriacontane. 



Histidine. 



Hypoxanthine. 



Lignoceric acid. 



Monohydroxystearie acid. 



Paraffinic acid. 



Pentosan. 



Pentose. 



Phytosterol. 



Picoline carboxylic acid. 



Resin. 



Resin acids. 



Resin esters. 



Xanthine. 



