November 1, 1912] 



SCIENCE 



577 



TBE OEGANIC CONSTITUENTS OF SOILS-' 

 The reports on the various phases of 

 soil studies by the investigators who have 

 preceded me in this symposium must have 

 impressed you with the fact that the sub- 

 ject of the soil's fertility and infertility is 

 by no means a simple matter of arithmetic, 

 which involves only a few of the mineral 

 constituents of the soil. It must also have 

 become clear to you that the problem of 

 the soil's fertility or infertility has not 

 been solved by the application of these 

 simple arithmetical means based on soil 

 analysis or by the crop statistics accumu- 

 lated in the years which have elapsed since 

 Liebig first announced his views on soil 

 fertility which gained for him for all time 

 the title of ' ' Father of Agricultural Chem- 

 istry." It is particularly gratifying to 

 me, since I am to talk to you to-day on the 

 subject of the organic constituents of soils, 

 of their chemical nature and other proper- 

 ties, that Liebig is also known as the 

 "Father of Organic Chemistry." To what 

 tremendous proportions and significance in 

 the world's industries and science this 

 child of his (organic chemistry) has grown 

 is familiar to all of you, and I assure you 

 that Liebig, were he to return to-day, 

 would be proud of its parentage. But I 

 fear he would be displeased with his other 

 child, as having made so little progress in 

 the intervening years, although he started 

 it in life strong and virile and full of 

 promise. Up to a few years ago agricul- 

 ture had not shared in the great impulses 

 which modern science has given to other 

 arts and industries, and the domination of 

 the mineral requirement theory proposed 

 in the first half of the last century and 

 accepted without adequate proof of its 

 validity is largely responsible for the lack 



^ Presented at the Symposium on Soils at the 

 Washington meeting of the American Association 

 for the Advancement of Science. 



of development in agriculture, commen- 

 surate with the enormous strides of other 

 arts and industries under the guidance of 

 modern scientific thought and research. 

 But a new era of scientific inquiry is at 

 hand and all phases of scientific endeavor 

 are being applied to the solution of the 

 problems connected with the soil 's fertility 

 and infertility — lines of scientific endeavor 

 which were not even known to Liebig 's 

 time, but which to-day are well-recognized 

 factors in soil fertility. I refer to soil 

 bacteria, soil fungi, soil protozoa and other 

 microorganisms, and all the biochemical 

 functions of these, as well as of the higher 

 plants, such as oxidation, reduction, en- 

 zymotic and catalytic, producing and de- 

 stroying in the soil the organic constituents, 

 of which I shall speak presently. The soil 

 is not simple, but complex. The soil prop- 

 erties and functions are likewise complex, 

 not simple. All of the investigators pre- 

 ceding me in this symposium have empha- 

 sized to you by their papers how complex 

 the subject is and how much remains to be 

 done before a clear insight is obtained, but 

 they have also shown to you clearly that a 

 well-trained army of scientists is at work 

 on the problems connected with soil fer- 

 tility, applying thereto all the principles 

 of modern science. The old view was sim- 

 plicity itself ; the soil was a mere trough in 

 which the plant found its nourishment. 

 But I can do no better than to let Liebig 

 speak for himself. I quote from Letter 

 XII. of his "Familiar Letters on Chem- 

 istry. ' ' 



A field in which we cultivate the same plant for 

 several successive years becomes barren for that 

 plant in a period varying with the nature of the 

 soil; in one field it will be three, in another seven, 

 in a third, twenty, in a fourth, a hundred years. 

 One field bears wheat and no peas; another beans 

 and turnips, but no tobacco; a third gives a 

 plentiful crop of turnips, but will not bear clover. 

 What is the reason that a field loses its fertility 



