582 



SCIENCE 



[N. S. Vol. XXXVI. No. 931 



compound or else it enables the plant to 

 resist or overcome its effect. 



Dihydroxystearic acid has another effect 

 which should here be mentioned as having 

 a considerable bearing on its effect on 

 crops, even in such soils as contain much 

 plant nutrient material in the most readily 

 available form. This is its influence on 

 the absorptive power of the roots of the 

 plants growing in the soil, the soU solu- 

 tion, or solutions of nutrient salts when 

 dihydroxystearic acid is present in them. 

 The absorption of potassium and phos- 

 phate was greatly interfered with, although 

 both were present in soluble form in the 

 culture solutions ; only the nitrate was con- 

 sumed in any quantity. This is in harmony 

 with the fact stated above that when ni- 

 trates were plentiful in the solutions, the 

 best growth was obtained and the effect 

 of the harmful compouad was minimized 

 or entirely overcome. 



The occurrence of dihydroxystearic acid 

 was specifically studied. For this purpose 

 soil samples of good and poor fields were 

 collected and examined for this constituent. 

 Soils from eighteen different states, ex- 

 tending from Maine to Oregon, and south- 

 ward to Texas, of widely different origin, 

 topography, texture, climate, drainage and 

 cropping, varying from soils of the highest 

 productivity to soils incapable of pro- 

 ducing 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 perma- 

 nent 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 doubt- 



less due to local conditions in any one sec- 

 tion, but those local soil conditions are not 

 confined to any region of the United States 

 and probably not to any country or conti- 

 nent. 



"When the soils examined are separated 

 into good and poor soils, as based on field 

 observations, their relationship with di- 

 hydroxystearic 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, the dihydroxystearic acid was 

 found in each and every case. 



Judging from the foregoing relation- 

 ships established by this investigation it 

 would seem that dihydroxystearic acid is 

 either a direct or indirect factor in the low 

 productivity in soils; direct by virtue of 

 its harmful effects on growing crops, indi- 

 rect as an indicator of other compounds or 

 conditions which cause soil to become less 

 productive and even infertile. It is not 

 possible to state from the data at hand that 

 dihydroxystearic acid is the only factor 

 which contributes to the infertility or un- 

 productivity in those soils in which it was 

 found, for it must be remembered that this 

 is only one of many compounds, both or- 

 ganic and inorganic, harmful and benefi- 

 cial, as I shall show presently, which exist 

 in soils, 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 hannful constituents is, 

 however, only a part of the entire field cov- 

 ered by these investigations into the nature 



