THE SOIL. 77 



bined within particles (such as pebbles, etc.), where 

 they are out of the reach of roots. 



In other cases, we find two soils, which are equal- 

 ly well pulverized, which are of the same color and 

 texture, and which appear to be of the same char- 

 acter, yet having very different power to support 

 crops. Chemical analysis, could it accurately show, 

 not only the kinds and quantities of plant food con- 

 tained in these soils, but the condition in which it 

 exists as to solubility, etc., would undoubtedly in- 

 dicate a very great difference between them. 



All of these differences may be overcome by the 

 use of the proper means. Sometimes it could be 

 done at an expense which would be justified by the 

 result ; and at others, it might require too large an 

 outlay to be profitable. It becomes a question of 

 economy, not of ability, and science is able to estimate 

 the cost. 



A soil cannot be cultivated understandingly until 

 it has been rigidly subjected to such examinations as 

 will tell us, as nearly as any examination can tell it, 

 what is necessary to render it fertile. Even after 

 fertility is perfectly restored it requires thought and 

 care to maintain it. The difi'erent ingredients oi 

 the soil must be returned in the form of manures as 

 largely as they are removed by the crop, or the sup- 

 ply will eventually become too small for the purposes 

 of vegetation. 



