NAT^URE AND PROPERTIES OF THE SOIL. 2^ 



The roots, which are the collectors of the nutriment, and are 

 withal of a tender and delicate texture, cannot easily stretch 

 themselves in a substance of such stiffness and tenacity; and 

 which besides, so readily consolidates after rain into a compact 

 body. Its closeness opposes material resistance to their extent 

 sion, and accordingly in its unmellowed state, the fibres arer 

 hampered from extending themselves. Besides, admitting that 

 they overcome in part this obstacle in the soil, they must, 

 whenever it hardens in the sun and gapes into chinks, be vio- 

 lently torn asunder and separated from the stem. If clay be so 

 hurtful on the surface, it is almost equally pernicious in the sub- 

 soil, from the capacity it has of interrupting the passage of wa- 

 ter downward, and keeping the roots perpetually drenched, an 

 evil no less destructive to the health and vigor of the plant than 

 the opposite extreme. All its qualities are unfriendly to vege- 

 tation, except its capacity of absorbing and retaining moisture, 

 and this is of so much importance, as in some measure, to make 

 atonement for its other defects. When existing by itself, this 

 virtue which it possesses in so eminent a degree, is useless and 

 unavailing ; but when mixed with other materials, of aloose and 

 friable nature, it gives tenacity and firmness to the whole, and 

 is highly retentive of the dews and rains which fall to fertilize 

 the soil. Sand or gravel, called sometimes silex, silica, silicious 

 matter, or earth of flints, is distinguished by properties of a to- 

 tally opposite character. Sand is incapable of retaining water 

 when poured upon it, and far less of attracting moisture from 

 the atmosphere. It powerfully promotes putrefaction, but al- 

 lows the gasses set at liberty, to escape. It has little or no co- 

 hesion among its parts, and never binds by the alternations of 

 wet and dry, into a compact body. It will appear from this ac- 

 count of the properties of sand, that it is provided as a correct- 

 er of alumine, or clay, and that in their effects, the two are des- 

 tined to counteract each other. Sand suffers water to filter ea- 

 sily ; clay is highly retentive : sand promotes putrefaction ; clay 

 delays it, but absorbs the gasses which are formed in the de- 

 composition: sand opens an unobstructed path for the exten- 

 sion of the roots : clay gives them firmness in their course, and 

 supplies the moisture which sustains them. Thus we see, that 



that one cause of the nnproductiveness of cold, clayey, adhesive 

 soils is, that the seed is coated with matter impenetrable to air, 

 and that in clayey soils, there can scarcely be toog^reat a mechan- 

 ical division of parts in the process of tillaofe. And seed, says he, 

 not fully supplied with air, always produces a weak and diseased 

 plant. 



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