540 POPULAR SCIENCE MONTHLY. 



Like all popular sayings, this one contains much truth. But it is 

 sometimes untrue or at least misleading. For whether or not the soil 

 be poor will depend entirely upon the point of view, and that there may 

 be at least more than one point of view for any given soil will, it is 

 believed, become evident from the following pages. Soils which are 

 seemingly poor, and supporting but a poor population, may be in fact, 

 or at least potentially, quite rich. But in order to make plain what is 

 meant, it will be well to point out briefly some of the facts that are now 

 known, and some of the views that are held by those who are making an 

 especial study of soils. It will not be necessary to go into very much 

 detail, for it will be sufficient to present the leading ideas in a general 

 way in order to show that the work of the physical scientist touches, as 

 a necessary consequence, both the field of economics and sociology. 

 From these points of contact the effort will be made to indicate a few 

 at least of the social and economic possibilities which a study of the 

 soil presents, and to submit a plea that those to whom we look as leaders 

 in these latter directions will find this subject of such importance and 

 of so much interest that they will be impelled to do something towards 

 the development of this side of it for the benefit of our country and 

 possibly mankind at large. It would seem, as indicated above, that an 

 almost virgin field for investigation is offered here, which can hardly 

 fail to yield rich rewards to the student. 



The soil is a very complex, heterogeneous mixture, or as one may say 

 technically, material system. It is composed of three distinct parts or 

 phases: First, the mineral and organic matters in a solid condition; 

 second, the water, or water solution, which all soils contain ; and third, 

 the gaseous part, which fills the interstitial spaces between the solid 

 components of the soil not occupied by the ground solutions. Further- 

 more, the soil is in contact with the atmosphere above it. It is probably 

 from the ground solutions alone, or almost entirely alone, that the 

 plants take their nutriment as far as the soil itself is concerned. Of 

 course it is perfectly well Iniown that the carbon and oxygen, which 

 form so large a part of the plant tissues, are obtained mainly from the 

 atmosphere above the soil and in contact with it. But the plant can 

 derive its mineral foods from the soil solution only, and it is upon the 

 concentration and composition of the solution that the well-being of the 

 plant is primarily dependent. The nature of this soil solution is in 

 turn dependent both upon the nature of the solid and of the gaseous 

 components of the soil. Furthermore, it is intimately connected with 

 the physical conditions of the soil — that is to say, with its texture, or 

 the size of the solid particles, and the structure, or the arrangement 

 of the particles, mainly because upon these factors depends the amount 

 of water which the soil will hold under any given conditions of tempera- 

 ture, climate, etc. And upon the amount of water which it will hold 



