ELIMINATION AND NEUTRALIZATION OF TOXIC 

 SOIL SUBSTANCES. 



By OSWALD SCHREINER, Ph.D., 



Chief of Division of Soil Fertility Investigations, Department 

 OF Agriculture, Washington. 



(Read April i8, 1913.) 



The fact that certain soils are naturally infertile, or if once fertile 

 are showing a decrease in their productive power, is a subject that 

 has engaged the attention of many able philosophers and scientists 

 during the centuries. Some of these have explained the infertility 

 as being caused by the absence or diminishing quantity of the store 

 of certain mineral soil components, others have contended that the 

 plant in its growth excreted waste substances, much as animals do, 

 and that this toxic material poisoned succeeding crops, especially if 

 they were of the same kind. The former of these views has led to 

 the practice of supplying minerals in the form of fertilizers, the 

 latter view, directly, or indirectly through dire necessity, to diver- 

 sified farming or crop rotation. Thus both lines of reasoning lead 

 to important practical results in maintaining and increasing the fer- 

 tility of our agricultural lands, but neither view can as yet be said 

 to have passed the controversial stage through which all great truths 

 must pass. 



I do not desire on this occasion to dwell on these two lines of 

 reasoning but rather to present some new soil facts which would 

 seem to coordinate the apparently opposite views and to modify both, 

 so that each becomes at least broad enough to be tolerant of the other. 

 I refer especially to the accumulating store of information gained 

 through modern chemical and biological research, as to the nature 

 of that portion of the soil components, variously designated as 

 organic matter, soil humus, humic acid, matiere noire, etc., and the 

 various biochemical changes which are taking place in soils, and 



420 



