26 AMERICAN AGRICULTURE. 



are afterwards distributed in their appropriate places in the 

 plant. Where this action has been going on for a long 

 period, a manifestly beneficial effect has immediately fol- 

 lowed, from bringing up and mixing with the superficial 

 earth, portions of the subsoil which have never before been 

 subject to cultivation. 



A subsoil which is permeable by water, is sometimes 

 imperceptibly beneficial to vegetation, not only by allowing 

 the latent moisture to ascend and yield a necessary supply 

 to the plants ; but a moisture frequently charged with lime 

 and various other salts, which the capillary attraction 

 brings from remote depths below the surface. It is probably 

 from this cause, that some soils produce crops far beyond the 

 yield which might be reasonably looked for, from the fertili- 

 sing materials actually contained in them. This operation 

 is rapidly going forward during the heat of summer. The 

 water thus charged with saline matters, ascends and evapo- 

 rates at and below the surface, leaving them diffused 

 throughout the soil. After long continued dry weather, a 

 thin, whitish coating of these salts, is frequently discernible 

 on the ground. The enriching effect of these deposites, is 

 one of the compensating results, seldom discovered or 

 acknowledged perhaps, yet wisely designed by a beneficent 

 Providence, to secure a future and increased fertility from the 

 temporary loss occasioned by drought. 



Where rain seldom or never falls, this result is noticeable 

 in numerous, and sometimes extensive beds of quiescent 

 (not shifting) sand. Deposits ofttimes occur several inches 

 in thickness. Such are the extensive beds of impure muri- 

 ate of soda and other salts, in the arid deserts of California ; 

 in the southern parts of Oregon ; the nitrates found in India, 

 Egypt, Peru, and various other parts of the world. 



ADDITIONAL PROPERTIES OF SOILS. 



Besides the qualities of soils already noticed, there are 

 several physical conditions which affect their value. They 

 should be of sufficient depth, friable or easily pulverized ; 

 they should possess the right color, and be susceptible of the 

 proper admission and escape of heat, air and moisture. 



Jethro Tull, who wrote more than a century ago on the 

 subject of agriculture, maintained that if a soil be worked to 

 a proper depth, and perfectly well pulverized, nothing more 

 is necessary to insure an indefinite succession of the most 



