PRACTICAL INFERENCES. 269 



taken views of reliojion have led them into that entire iso- 

 lation from human society, under which even the severest 

 physical toil becomes itself a relief. 



*'The same principle explains in some degree the utility 

 of subsoil-ploughing, which, by bringing up to the surface 

 a portion of earth previously out of the reach of those in- 

 fluences which tend to cause its disintegration, extracts 

 from it the alkaline and other ingredients required by the 

 plant for its subsistence. 



** It is found advantageous, in the first instance, merely 

 to break and pulverize the subsoil to a depth of eighteen 

 or twenty inches, without bringing it to the surface, and 

 only after a lapse of four or five years to mix it with the 

 vegetable mould above, a practice, the utility of which de- 

 pends, not only on the mechanical condition of the land 

 being rendered more favorable to culture in consequence 

 of its becoming more friable, but likewise, probably, owing 

 to the chemical decomposition of its component parts having 

 taken place more completely. 



*' Other circumstances, such as its influence on the drain- 

 age of the land, will no doubt cooperate in producing the 

 benefit which often results from the practice of subsoiling ; 

 but that the cause pointed out really contributes to its 

 efficacy, may be inferred from a fact attested by many ex- 

 perienced agriculturists,* namely, that those soils are most 

 benefited by subsoil-ploughing, which can be rendered 

 thereby more pervious to moisture, and consequently to 

 air ; whilst those which contain too large a percentage of 

 clay to be aflTected in this manner by the process, derive 

 no advantaoje from it. 



*'But it must not be forgotten, that the utmost pains be- 

 stowed upon its elaboration cannot generate any new prin- 

 ciples, but only act, by enabling the soil to impart more 

 readily to the crop those which it already possesses. 



** This obvious truth will explain the cause of the disap- 

 pointment felt by farmers, at finding, that afi;er a certain 

 time, the most diligent tillage no longer affords them the 

 same returns as it did at first. 



'*It it said, that Jethro Tull, who first proved the ad- 

 vantages of deepening and pulverizing soils, was neverthe- 

 less obliged at length to admit, that at each repetition of 

 the experiment the success was less decided, unless manure 

 were at the same time applied. Judicious tillage, in short, 



" • See English Agricultural Journal^ No. 5, p. 32." 



23* 



