ORGANIC CONSTITUENTS OF SOILS. 17 



agement, and the altered biochemical changes produced in the dif- 

 ferent plant remains. 



The soil has vital functions. The soil can not be considered as 

 the dead, inert remains of rocks and previous vegetation, but must 

 be considered as an accumulation of such material in which the proc- 

 esses of formation, alteration, and transposition are still at work. 

 In other words, the soil in its entirety is not dead or inert, but endowed 

 with functions analogous to those of life itself. In it take place the 

 same processes of solution and deposition that have taken place in 

 past ages and are taking place to-day in the geologic processes con- 

 nected with the action of water on the rocks and minerals of the 

 earth's crust. In it take place the same physical and chemical inter- 

 actions as take place in the movement of subsurface waters generally, 

 resulting in ore formations or depositions. In it take place the same 

 processes of fermentation, digestion, or decay of organic materials 

 that take place in animals and plants or in the production of industrial 

 products, such as cheeses, wines, and beers, brought about in the 

 soil as in these other processes by means of ferments, enzymes, 

 bacteria, and fungi or molds. In it take place the same processes of 

 oxidation and reduction which play so enormous a part in all life 

 processes, and recent researches have shown the nature of compounds 

 in the soil organic matter to be the same as those derived from such 

 life processes or from similar laboratory processes of digestion, oxida- 

 tion, or reduction. Organic matter is very changeable; it is the 

 material which forms the food, as it were, of all the micro-organisms 

 of the soil of the bacteria, of the molds, of the protozoa and 

 influences them favorably or unfavorably, just as the higher plants 

 are affected. In turn, these agents are great promoters of changes 

 in the organic debris of soil. All of these processes and the life forms 

 in the soil are affected by fertilizer salts when added to the soil, and 

 changes are produced in the soil, physical, chemical, and biochemical, 

 which influence it and affect its potential fertility entirely irrespective 

 of the added plant food. In other words, the soil has been changed 

 in many prominent characteristics, even before any crop is planted 

 therein. 



I must not leave this subject of fertilizer action without saying 

 that the Bureau of Soils takes a very advanced view, not only on the 

 present use of fertilizers, but on their extension in agriculture, in 

 spite of reiterated statements to the contrary. The point of differ- 

 ence between certain other investigators and the Bureau of Soils lies 

 in the explanation of the action of fertilizers, one view being that 

 they are merely so much plant food which must replace that removed 

 by crops, the other being that in addition to any plant food value 

 which they possess they affect the soil and produce changes and 



