12 OBGANIC CONSTITUENTS OF SOILS. 



different origin, topography, texture, climate, drainage, and crop- 

 ping, varying from soils of the highest productivity to soils incapable 

 of producing profitable crops, were examined for dihydroxystearic 

 acid. 



One-third of all the soils examined showed the presence of this 

 compound. It was found in virgin soils as well as in soils under 

 long cultivation; in soils continually cropped as well as in soils under 

 permanent sod; in soils from the Atlantic coast; in soils from the 

 Pacific coast; and in soils from the Gulf States. This compound is 

 therefore a common soil constituent and is likely to be encountered 

 in soils anywhere. Its formation or its accumulation is doubtless 

 due to local conditions in any one section, but these local soil con- 

 ditions are not confined to any region of the United States and prob- 

 ably not to any country or continent. 



When the soils examined are separated into good and poor soils, as 

 based on field observations, their relationship with dihydroxystearic 

 acid is rather striking. Among the good soils only two contained 

 dihydroxystearic acid, and they were of only moderate productivity. 

 Among the poor soils the number of those containing this compound 

 was approximately one-half. Of the soils which had a definite 

 record for infertility, dihydroxystearic acid was found in each and 

 every case. 



Judging from the foregoing relationships established by this inves- 

 tigation, it would seem that diliydroxystearic acid is either a direct 

 or indirect factor in the low productivity of soils; direct by virtue 

 of its harmful effects on growing crops, indirect as an indicator of 

 other compounds or conditions which cause soil to become less pro- 

 ductive and even infertile. It is not possible to state from the data 

 at hand that dihydroxystearic acid is the only factor which con- 

 tributes to the infertility or unproductivity of those soils in which 

 it was found, for it must be remembered that this is only one of many 

 compounds, both organic and inorganic, harmful and beneficial, as 

 I shall show presently, which exist in the soil, any and all of which 

 play a part in its relative fertility and infertility. It is certain, 

 however, that the determination of even this one constituent leads 

 to a recognition of the kind of infertility in the soils examined, and 

 is therefore a readily recognized symptomatic factor of poor soil 

 conditions. 



The isolation of harmful constituents is, however, only a part 

 of the entire field covered by these investigations into the nature 

 and properties of soil organic matter, and I am very glad to be able 

 to announce to you the existence in the soil of organic compounds 

 decidedly beneficial to plant growth. Here, for example, is a speci- 

 men of creatinine, a nitrogenous compound, which we have isolated 

 from soils. The occurrence of this compound has always been asso- 



