THE ORGANIC MATTER OF THE SOIL 109 



conditions of poor drainage and aeration. The toxicity of 

 sucli compounds as dihydroxystearic acid, picoline carboxylic 

 acid and aldehydes may, therefore, be overcome by oxidation.^ 

 Good soil aeration is a factor in dealing with such conditions. 



Fertilizers, according to Schreiner and Skinner,^ seem to 

 decrease the harmful effects of such compounds; nitrogenous 

 fertilizers overcoming some toxic materials, and phosphoric 

 acid or potash neutralizing others. Robbins ^ has sho^vn that 

 soil organisms have the power of causing the disappearance 

 of certain toxic materials in the soil, such as cumarin, vanillin, 

 pyridine, and quinoline. 



While Schreiner found twenty soils, out of a group of sixty 

 taken in eleven states of this country, to contain dihydroxy- 

 stearic acid, this does not necessarily mean that this or sim- 

 ilar compounds are serious detrimental factors. It is very 

 likely that such compounds are merely products of improper 

 soil conditions, and are to be considered as concomitant with 

 depressed crop yield. When such conditions are righted, the 

 so-called toxic matter will disappear, as has been shown by 

 the researches of Davidson.^ Good drainage, lime, tillage, 

 aeration, and oxidation, are so efBcacious in this regard that 

 permanent organic soil toxicity need never be a factor in soils 



rationally managed. 



^ iSchreiner, 0., and Others, Certain Organic Constituents of Soils in 

 Belation to Soil Fertility; V, S. Bept. Agr., Bur. Soils, Bui. 47, p. 52, 

 1907. Also, Schreiner, 0., and Eeed, H. S., The Mole of Oxidation in 

 Soil Fertility; U. S. Dept. Agr., Bur. Soils, BuL m, p. 52, 1906. 



^Schreiner, 0., and Skinner, J. J., Organic Compounds and Fertiliser 

 Action; U. S. Dept. Agr., Bur. Soils, Bui. 77, 1911. Also, Experi- 

 mental Study of the Effect of Some of the Nitrogenous Soil Constituents 

 on Growth; Plant World, Vol. 16, No. 2, pp. 45-60, Feb., 1913. 



^ Robbins, W. X, The Cause of the Disappearance of Cwmarin, VanilUn, 

 Pyridine and Quinoline in the Soil; Ala. Agr. Exp. Sta., BuL 195, June, 

 1917. Also, The Destruction of Vanillin in the Soil hy the Action of 

 Soil Bacteria; Ala. Agr. Exp. Sta., Bui. 204, June, 1918. Robbins, W. J., 

 and Massey, A. B., The Effect of Certain Environmental Conditions on 

 the Bate of Destruction of Vanillin ly a Soil Bacterium; Soil Sci., 

 Vol. X, No. 3, pp. 237-246, Sept., 1920. 



* Davidson, J., A Comparative Study of the Effects of Cumarin and 

 Vanillin on Wheat Grouii in Soil, Sand and Water Culture; Jour. 

 Amer. Soc. Agron,, Vol. 7, No, 4, pp. 145-158, 1915. 



