THE ORGANIC MATTER OF THE SOIL 137 



>xic materials of the soil humus largely originate under 

 conditions of poor drainage and aeration, and conse- 

 quently are biological in their genesis. The toxicity of 

 such compounds as dihydroxystearic acid, picoline car- 

 boxy lie acid, 1 and aldehydes 2 may therefore be overcome 

 by oxidation, 3 so that good soil aeration is a factor in 

 dealing with such conditions. Insufficient sanitation 

 of the soil seems to account very largely for the presence 

 of soil toxines. Fertilizers, according to Schreiner and 

 Skinner, 4 seem to decrease the harmful effects of such 

 compounds; nitrogenous fertilizers overcoming some 

 toxic materials, and phosphorus or potash neutralizing 

 others. For example, in water solution and sand culture, 

 nitrogen seems especially efficacious in correcting such 

 toxic substances as dihydroxystearic acid and vanillin, 

 phosphorus is particularly powerful in counteracting 

 cumarine, and potash has considerable influence on 

 quinone. 



While the real importance of the toxic material generated 

 in the soil cannot be fully discussed at this point, it is 

 quite evident that such constituents do tend to develop 

 under insanitary conditions and must be considered in 



1 Schreiner, O., and Skinner, J. J. The Isolation of Harm- 

 ful Organic Substances from Soils. U. S. D. A., Bur. Soils, 

 Bui. 53, pp. 46-49. 1909. 



2 Schreiner, O., and Skinner, J. J. Harmful Effects of 

 Aldehydes in Soils. U. S. D. A., Bui. 108 (Professional Paper). 

 1914. 



3 Schreiner, O., and others. Certain Organic Constituents 

 of Soils in Relation to Soil Fertility. U. S. D. A., Bur. Soils, 

 Bui. 47, p. 52. 1907. Also, Schreiner, O., and Reed, H. S. 

 The Role of Oxidation in Soil Fertility. U. S. D. A., Bur. 

 Soils, Bui. 56, p. 52. 1906. 



4 Schreiner, O., and Skinner, J. J. Organic Compounds and 

 Fertilizer Action. U. S. D. A., Bur. Soils, Bui. 77. 1911. 



