Ch. IV.] DEPTH OF PLOUGHING. 51 



proportionate strength to the lower part of the stem, maintains its freshness 

 with greater vigour in times of drought, and is less subject to be laid by- 

 storms of wind or rain. It is almost unnecessary to add, that depth of soil 

 is equally advantageous to every crop, the roots of which go deeper into 

 the soil than those of corn, though its progressive increase in value is not 

 so great as that which lies nearer to the surface. 



In order to maintain the properties of a deep soil in a perfect state, it is, 

 however, expedient to plough it from time to time to the full depth of the 

 vegetative stratum ; so that, being completely worked by frequent turnings, 

 it may be freely exposed to the influence of the atmosphere. If that be not 

 done, or only superficially performed, the ground will, by slow degrees, be- 

 come gradually impoverished ; for, besides being deprived of the benefit of 

 exposure to the air, a crust of hard and almost impenetrable matter will, in 

 some soils, be formed immediately below that portion upon which the plough 

 was usually made to act, thus constituting a barrier between the upper sur- 

 face and the subsoil, which is well known to farmers under the appellation 

 of the moor-band, or pan. It is not, however, necessary to repeat the ope- 

 ration, even on heavy land, more than, perhaps, once in six or seven years, 

 especially if the intermediate ploughings under the common course of culti- 

 vation be made at various depths ; for nothing tends more to the formation 

 of tlie pan than the constant repetition of the j^rocess at the same depth. 

 Thus it will not escape observation, that one great advantage of the alter- 

 nate system of husbandry arises from the distinct nature of the different 

 roots which are cultivated, and the consequent necessity of ploughing at 

 various depths, so as to afford tliem room to seek for sustenance. On 

 tenacious clays, which, being confined to the growth of grain, are usually 

 ploughed to the same depth, it also forms a strong reason for the adoption 

 of the summer fallow. 



The maintenance of the properties of the soil in its original state is, how- 

 ever, a very different mode of procedure from that required by an endeavour 

 to restore it to perfection ; for there is much land of a deep and naturally 

 mellow staple, the lower strata of which have been rendered sterile by 

 shallow ploughing, and can only be progressively renovated by gradual 

 degrees ; or, according to the practice of those farmers who " like to go 

 deep enough to chip up the dead soil now and then, and show it a little 

 upon the surface after all is finished*.'' Many instances have, indeed, 

 been recorded in which the subsoil, when brought to the surface and exposed 

 for some time, has proved extremely fertile ; but in all those cases, the 

 earth, when chemically analyzed, has been found to contain a considerable 

 portion of carbon, and unless afterwards sustained by proportionate quan- 

 tities of manure, its good qualities have been speedily exhausted. It cannot, 

 therefore, be deemed generally expedient to bring up a greater quantity than 

 at the most two inclies of the virgin earth, even supposing it to be naturally 

 of the best average quality. The operation should be performed before the 

 winter, and the soil should be incorporated by the means of a summer 

 fallow ; observing, however, that its main object being to expose this 

 fresh substance to the atmosphere, it should be left as long as possible 

 on the surface. The manure should be also applied at the same time, 

 and, instead of being mixed up with the soil, should be spread uni- 

 formly over this layer of new earth, which thus imbibes its juices during 

 the whole of the wet season, and, notwithstanding all the objections which 

 have been urged against the evaporation of dungfj never fails to produce a 



* Survey of Essex, vol. i., p. 198. 



t On the subject of evaporation, see vol, i., chap. %., pp. 239 and 248. If the land 



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