320 ErFECT OF THE SUBSOIL-PLOUGH. 



branches in every direction. A deep soil is not absolutely necessary fo 

 the production of valuable crops. A well-pulverised and mellow soil, 

 to which the air and the roots have every where ready access, will, 

 though shallow, less frequently disappoint the hopes of the husbandman, 

 — than where a greater depth prevails, less permeable to the air, and 

 therefore less wholesome to the growing roots. 



II. Subsoil Ploughing. — And yet, as a general rule, it cannot be de- 

 nied that a deep soil is greatly superior in value to a shallow soil of the 

 same nature. It is so both to the owner and to the occupier, though m 

 too many cases the available qualities of deep Sf*''ls have hitherto been 

 more or less overlooked and neglected. 



The general theoretical priHciple on this subjet ': — that the deeper the 

 soil the longer it may be cropped without the risk of exhaustion, and the 

 greater the variety of crops, deep as well as shallow-rooted, which may 

 be grown upon it — is so reasonable in itself, as to command a ready ac- 

 quiescence. But a soil is virtually shallow where a few inches of porous 

 earth, often turned by the plough, rest upon a subsoil, hard, stiffs and al- 

 most impervious, — and the practical farmer will rarely be willing to 

 allow the depth of the latter to influence his opinion in regard to the gene- 

 ral value of the land. And in this he is so far correct, that a subsoil 

 must be dried, opened up, mellowed by the air, and rendered at once 

 pervious and wholesome to the roots of plants, before it can be made 

 available for the growth of corn. This may be effected, after draining, 

 by the use of the subsoil plough, an instrument at present, I believe, 

 imequalled for giving a real, practical, and money-value to stiff" and 

 hitherto almost worthless clayey subsoils. It is an auxiliary both to the 

 surface plough and to the drain, and the source of its efficacy will appear 

 from the following considerations : 



1°. The surface plough turns over and loosens the soil to the depth of 

 6 to 10 inches — the subsoil plough tears open and loosens it to a further 

 depth of 8 or 10 inches. Thus the water obtains a more easy descent, 

 and the air penetrates, and roots more readily make their way among 

 the particles of the under-soil. So far it is an auxiliary to the common 

 plough, and assists it in aerating and mellowing the soil. 



2°. But though it opens up the soil for a time to a greater depth, the 

 subsoil plough will in most cases afford no permanent cure for the defi- 

 ciencies of the subsoil, if unaided hy the drain. If the soil rest upon 

 an indurated substratum — upon a calcareous or ochrey j^an — this plough 

 may tear it up, may thus allow the surface water to sink, and may great- 

 ly benefit the land ; but the same petrifyiDg action will again recur, and 

 I'he benefit of the subsoiling will slowly disappear. Or, if the subsoil 

 contain some noxious ingredients, such as salts of iron, which the ad- 

 mission of air is- fitted to render harmless, then the use of this plough 

 may afford a partial amelioration. But in this case, also, the efl^ect will 

 be only temporary ; since the source of the evil has not been removed, 

 the same noxious compounds will again be naturally produced, or will 

 again, in fresh supplies, be conveyed into the soil by springs. Or, if the 

 subsoil be a sliff'clay, containing no noxious ingredient, it may be cut, or 

 for the time torn asunder, but scarcely will the plough have passed over 

 it till the particles will be again cemented together, and probably, by the 



