756 



SCIENCE. 



[N. S. Vol. XVIII. No. 407. 



over and allowed to run its coursS. But when 

 it emanates from the head of the Bureau of 

 Soils in the United States Department of 

 Agriculture, and is expressly and persistently 

 given as the opinion of that bureau, it can 

 not be thus passed over unchallenged. 



The above quotation from page 7 of the 

 bulletin practically prejudges, or begs, the 

 main question at issue. To any one outside 

 of the bureau the cogency of this statement 

 is far from apparent, except in so far as it 

 may mean what has long been known and rec- 

 ognized, and need not, therefore, have been 

 shown anew by the bureau. 



If we examine the experimental basis upon 

 which all these assertions are made, we find 

 it to be the assumption that the aqueous soil 

 solution is the exclusive source through which 

 plants derive their food; and the fact, assumed 

 to be demonstrated by a newly devised method 

 of analysis, that that solution is practically 

 of the same composition in all soils, so far as 

 the mainly important plant-food ingredients 

 are concerned. Throughout the bulletin the 

 determinations thus made are considered and 

 mentioned as constituting an ' exhaustive in- 

 vestigation of many types of soils, by very 

 accurate methods of analysis.' 



It is not the intention of the present writer 

 to question the accuracy of the analyses, such 

 as they are. But it is notorious that there are 

 a great many methods that may and have been 

 used for the chemical analysis of soils, each 

 susceptible of great analytical accuracy, but 

 in many if not in most cases having no prac- 

 tical bearing upon the agricultural value of 

 the soils analyzed. The method of ultimate 

 silicate analysis is one ; and it is generally con- 

 ceded that the results so obtained have but a 

 very remote bearing upon the practical value 

 of a soil. The method of extraction with dis- 

 tilled water is another; it is the opposite ex- 

 treme, and unlike the silicate analysis, can 

 certainly not be considered ' exhaustive.' 



Now the criterion usually applied to the 

 relevancy of soil analyses is whether they will 

 stand the test of agricultural practice. Judged 

 by this test, both the ultimate analysis and 

 that by distilled water are, equally, failures, 

 according to Whitney's own testimony. But 



his conclusion is that since his method fails 

 as a criterion of rich and poor soils, therefore 

 the chemical composition of soils has no bear- 

 ing upon crop production; and that, there- 

 fore, ' the chief factor determining the yield 

 is the jshysical condition of the soil under 

 suitable conditions.' 



To this assertion ' non sequitur ! ' is the 

 obvious first answer. But before discussing 

 it, it seems proper to recall, as regards the 

 personal standpoint of the present writer, that 

 he was the first one to undertake systematic 

 physical soil work in the United States, in the 

 early sixties; and has steadily pursued it ever 

 since, as his publications* show. He has 

 always held, taught and written that the phys- 

 ical soil conditions are the first thing needful 

 to be considered in the estimate of a soil's 

 practical value, the chemical composition sec- 

 ond; since faults in the latter can in most 

 cases be much more readily remedied than 

 faulty physical conditions. But that chem- 

 ical composition is the chief determining fac- 

 tor of phytogeography in the humid region, 

 and inferentially of crop production within 

 the same, became his conviction in the prose- 

 cution of the agricultural survey of Missis- 

 sippi; and hence he made it prominent in his 

 work in that state. In the arid region, where 

 moisture is the dominant factor, and soil com- 

 position much less varied, soil physics has 

 received his chief attention. It can not, 

 therefore, be truthfully said that the writer 

 has not fully recognized the enormous im- 

 portance of physical soil conditions, both in 

 his teachings and his publications. 



Eleven years ago it fell to his lot to contro- 

 vert the hj^othesis then put forth by Whitney, 

 to the effect that fertilizers act, not by con- 

 veying nourishment to plants, but by modify- 

 ing the physical texture of the soil.f The 

 recent enunciation of the chief of the Bureau 



* Proc. A. A. A. S., 1872, 1873; Amer. Jour. 

 Sci., 1872, 1873, 1879; Proc. Soc. Prom. Agr. ScL, 

 1882-1898; ' Wollny's Forscli.,' 1879-1896; Cen- 

 tralblatt fiir Agriculturchemie, 1886; Agr. Sei., 

 1892; Jour. Amer. Chem. Soc, 1894; U. S. Weather 

 Bureau Bull. No. 3, 1892; Ann. de la Sci. Agron., 

 1892; Calif. Agr. Expt. Sta. Reports and Bul- 

 letins, 1877-1903. 



t Agr. Sci., 1892, pp. 321, 566. 



