xx PREFACE. 



Europe, with its long-cropped, worn fields, and very predomi- 

 nantly calcareous soils, the present condition of this science 

 might differ not immaterially from that actually existing. As 

 a matter of fact, it has attained its present state under very 

 disadvantageous external conditions, which frequently necessi- 

 tated a recourse to highly complex and laborious methods and 

 artificial appliances, for the establishment and maintenance 

 of the conditions which elsewhere might have been found 

 abundantly realized in nature; thus permitting, by the multi- 

 plication of observations over extended and widely varied areas, 

 the elimination and control of accidental errors of experiment 

 and observation. 



Just as in historical geology the subdivisions of formations 

 observed and accepted in Europe formed for many years a pro- 

 crustean bed upon which the facts observed elsewhere had to 

 be stretched, so in the domain of soil physics and chemistry, 

 and even in vegetable physiology, the observations made in the 

 really exceptional climates and soils of middle Western 

 Europe, have often erroneously been construed as constituting 

 a general basis for unalterable deductions. 



The rapid extension of civilization and the carrying of 

 minute scientific research into other regions, now rendered 

 possible by the improved means of communication, has shown 

 the one-sidedness of some of the views prevailing heretofore, 

 inasmuch as they are really applicable only to accidental and 

 rather exceptional conditions. 



It is therefore one object of this volume to present and 

 discuss summarily the facts of physical and chemical soil con- 

 stitution and functions with reference to the additional light 

 afforded on the wider basis, embracing both the humid and the 

 arid regions ; of which the latter has, as such, received but scant 

 and desultory attention thus far, to the detriment of both the 

 work of the agricultural experiment stations and of agricul- 

 tural practice. The book therefore includes the discussion 

 both of the methods and results of direct physical, chemical and 

 botanical soil investigation, as well as the subject matter relat- 

 ing to the origin, formation, classification and physical as well 

 as chemical nature of soil, usually included in works on scien- 

 tific agriculture. 



In the presentation of these subjects, it has been the writer's 



