Ch. IV.] DEPTH OF PLOUGHING. 53 



and downs, carefully avoid ploughing below the top-soil : for when there is 

 a vein of rubbly chalk, or of small broken flints, immediately under the top- 

 soil, they look upon it as " the dross of the land," and that, if ploughed 

 up, it is quite poison to the field*. 



If the land be of a sandy nature, the ploughing of which has been 

 always carried to one depth, and that a pan has thus been formed under- 

 neath, in that case, also, it is injudicious to break it up; for, independently 

 of the labour of the operation, the surface may have been much ameliorated 

 by good culture, and the hard crust which lies at the bottom both secures 

 the manure from being carried down below that part which is actually tilled, 

 and also prevents the escape of humidity from the upper stratum. Another 

 layer of sand, indeed, not unfrequently exists under the pan ; for that species 

 of crust is often found where land has been much marled ; but although it 

 might be desirable to have it at a greater depth, yet its removal is a work 

 of extreme difficulty, and, on sucli soils, will rarely repay the expense. On 

 sand veins where there is a great depth of soil, and in which no obstruction 

 of this kind is found, it is however not unusual to plough very deep, and 

 to have a second plough following in the furrow of the first, so as to throw 

 up new soil, and to bury that which is supposed to be exhausted : as is the 

 case in many parts of Devonshiref. 



In fine, it will, in most cases, be found inexpedient to add to the stratum 

 already under tillage by any other means than those wliich, little by little, 

 may gradually tend to increase the depth of vegetative mould by the mix- 

 ture of small quantities of the virgin earth of the subsoil with the surface ; 

 but if a more extensive operation be contemplated, then the following ques- 

 tions may be not unaptly put before coming to a conclusion. 



1st, What return may be expected from land, the subsoil of which 

 has not yet been submitted to the plough ? 



2ndly, AVhat change will be occasioned, either by the increase or 

 diminution of the tenacity, or of the friability of the land, by the admix- 

 ture of the subsoil with the surface ? 



3rdly, What quantity of manure will be required beyond that already 

 disposable upon the farm ? and 



4thly, What will be the entire cost ? 

 To solve which, the earth should either be submitted to a chemical analysis, 

 or its qualities ascertained by spreading some of it, to a certain depth, in a 

 garden, and sowing seeds upon it. The probable improvement in the soil 

 may thus be ascertained, and the supposed increase in the future crops, 

 when compared with the expenditure, will determine the propriety of the 

 experiment. 



We have not hitherto touched upon the subject of the aciuctl depth to 

 which ■ploughing is commonly carried, nor is it necessary to say much re- 

 garding it ; for it of course depends more upon the state of the land and 

 the judgment of the farmer than upon any general rule. The usual operation 

 is generally confined to from four to five, and rarely exceeds seven inches ; 

 though, in tl)e hundreds of Essex, and some other districts where the soil 

 is rich and deep, it is sometimes carried as far as nine. An opinion is indeed 

 entertained that, if carried deeper, more manure is necessary to ensure a 

 crop ; and it will be readily admitted that, were this idea well founded, it 



* " Many instances are shown where land of this kind, ploughed too deep upwards of 

 twenty years ago, has not yet recovered its former goodness; and, to keep the top-soil as 

 deep as possible, the best farmers will not permit the surface-flints to be picked ofi' for the 

 roads, lest it should make the land both lighter and thinner." — Davis's Survey of tf\lU 

 shire, p. 52. -j- Ibid. 



