THE CAUSE OF THE DISAPPEARANCE 



OF CUMARIN, VANILLIN, PYRIDINE 



AND QUINOLINE IN THE SOIL^ 



By 



William J. Robbins, Botanist, 

 Alabama Agricultural Experiment Station. 



Since the proposal of the soil toxin theory of soil 

 fertility by DeCandolle (4) = in 1832, and its further 

 elaboration in recent years by the Bureau of Soils of 

 the U. S. Department of Agriculture, evidence has been 

 offered to support or discredit it along several lines. 

 One of these has been the demonstration that organic 

 substances, either found in the soil or reasonably as- 

 sumed to be there, are toxic to crop plants in water 

 culture. As a further step in this same direction, the 

 effect on plants of these substances, when added to the 

 soil, has been studied, 



The results obtained when the compounds are added 

 to the soil have been conflicting. Some investigators 

 have found that the compounds which are toxic to 

 plants in water culture are decidedly harmful when 

 added to the soil. They have also found that the com- 

 pound and its toxic effects persist for a considerable 

 space of time. Others have found that the same com- 

 pounds have little or no toxic action in the soil or even 

 prove decidedly beneficial to the growth of the plants. 

 They have also found that the compounds disappear 

 rapidly in the soil. 



The work recorded in the following pages was under- 

 taken to determine the cause of the disappearance of 

 these compounds in the soil. With a clear understand- 

 ing of why they disappear in one soil, it would appear 

 possible to explain why they persist in other soils and 

 to examine intelligently methods for eliminating them 

 from soils in which they arc known to exist and in 

 which they may be a contributing cause to infertility. 



' The writer wishes to express his indebtedness to Mr. A. 

 E. Elizondo for careful and conscientious assistance. 



- Reference is made by nundier to "Literature Cited," p. 63.. 



