Burning clay soils is in fact something analogous to liming. Lime dissolves the vegetable matter and sets free the alkalies, and it enables the detached elements to enter into new combinations ; but if no new vegetable matter be added to restore what is exhausted by vegetation, liming, as well as paring and burning, is detrimental in the end. Many experienced farmers pare and burn the soil on the edges of their ditches and on the banks on which the hedges grow, because they thereby exterminate many rank weeds; and the burnt earth mixed with farm yard dung makes an admirable compost. Here the burnt earth acts as an absorbent, and no doubt attracts many of the volatile parts of the manure, which are produced by the decomposition of animal and vegetable matter in it. Paring and burning therefore should be joined to manuring, if a powerful and immediate effect is desired without exhausting the soil; and in this case we do not hesitate to recommend it on all cold clay soils where rank weeds are apt to spring up, and coarse grasses take the place of the better sorts which have been sown. The proper time to pare and burn is evidently after the land has lain in grass for several years, and is broken up for tillage. The surface should be pared thin; about two inches is the extreme thickness allowable for the sod if the soil is very stiff and poor, and as thin as possible in a better soil. The sods should be moderately dried, and then arranged into small heaps with a hollow in the middle to hold heath or bushes to kindle the fire. When it has fairly established itself, all the apertures should be carefully closed. Wherever any fire breaks out, a fresh sod should be immediately put over it ; a heap containing a small cart-load of sods should be smouldering for several days without going out, even if it rains hard. If the fire is too brisk, the earth will form hard lumps, and even vitrify ; but otherwise it comes out in the form of a fine powder, in which evident marks of charcoal appear. If this is of a fine red colour, it is a good sign ; for the iron in the earth has been converted into a peroxide, which is perfectly innocent in its effects on vegetation, whereas all the saline impregnations of iron are more or less hurtful. It is better to burn the sods in large than in small heaps ; for the more the fire is smothered, the better the ashes.
So great a quantity of ashes is sometimes produced as to admit of a portion being carried off on grass-land, or used to manure another field for turnips. As this is evidently robbing the field where the operation has been carried on, an equivalent quantity of manure should be brought in exchange. Perhaps the most advantageous mode of using the ashes is to spread them in the drills where the turnip-seed is to be sown, after a portion of dung has been buried under them. In this manner the ashes from one acre of land pared and burnt, together with ten or twelve cart-loads of good yard dung, and a half dressing of superphosphate of lime, will manure two acres, and all the manure of one acre, in the ordinary mode of raising turnips on ridges, will be saved. If the ashes will produce as good turnips with half the usual quantity of dung, the expense of paring and burning is amply repaid. But experience proves that the earth and ashes almost ensure a good crop of turnips in many poor stiff soils in which they would probably not have succeeded if sown in the common course of cultivation without bones or ashes.
When a considerable extent of poor land is brought into cultivation, and there is no sufficient supply of manure at hand, paring and burning a portion of the land every year, by which a crop of turnips is obtained, is a most effectual means of improvement. Lime may be used at the same time with the ashes, and will increase their effect, provided some vegetable undecayed matter remains in the soil after paring ; but lime will tend to exhaust this ; and if, in consequence of liming, a few good crops of corn are obtained at first, the soil will be so exhausted as to be of little value afterwards. This is the abuse of
the practice, which has caused it to come into disrepute. It would be a great waste to burn the surface of a rich piece of grass-land where the plants growing in it are tender and succulent, and would readily rot on being ploughed under ; in such case a moderate application of lime would have a much better effect. This kind of land will produce good crops without any manure, and continue fertile for many years if judiciously cultivated. To pare and burn rich laud is wasteful, and can never be recommended. It is only on poor land which has not strength to produce a crop, and of which the texture requires to be improved and its powers stimulated, that paring and burning is advantageous; on poor thin chalky soils which have been laid down with sainfoin, of which the roots and stems arc grown coarse and hard, no as not readily to rot in the ground, the operation is proper and advantageous. The turnips produced by the ashes, with or without the assistance of dung, must be fed off by sheep folded ou the land, whose dung and urine will enrich it, and their tread consolidate it. By this mode of proceeding great advantages are obtained from paring and burning, and the land, so far from being deteriorated, will be improved.
Many landlords rigidly forbid their tenants to pare and burn any part of their land, from an idea that the heart of it is destroyed by the burning. But in the hands of an intelligent tenant the practice is perfectly safe and even beneficial, for he knows it to be his interest to apply a certain quantity of dung, either at the same time that the land is thus treated, or for the next crop, and where under farming there is no sowing of cone crops except after turnips, clover, or some other green crop consumed on the farm, there could be little danger of any detriment to the land, even if it were pared and burnt once in every tea or twelve years, provided It were judiciously treated In the Intervale The farmer would be benefited in many situations, and the practice would tend to keep up the value of the farms.
In Devonshire, where the land has been pared and burnt from time immemorial, even where the boil Is rich, the practice has been often resorted to without any judgment. Provided I crop of corn or potatoes was obtained at little oast, the consequences to the future state of the land were not heeded ; and landlords, seeing their farms impoveriahed. put a stop to the practice. Thus many useful 'notice of cultivation have been reprobated from the abuse of them, which, proiwrly applied, would have been advantageous to all parties. There L no maxim more true than this : that whatever injures the landlord, injures the farmer who is not desirous of removing, and rice rersil ; and all positive restrictions on cultivation, however necessary when there is a fear of dishonest conduct, diminish the value of a farm and lemon the rent which can be fairly afforded for it. Ignorance is often a greater destroyer of the interest of both landlord and tenant than wilful dithontrty ; and the spreading of useful information amongst tenants, so that they may see their own advantage, Is the surestaneans of improving landed property. Many tracts of waste land might be brought into cultivation by means of paring and burning, which without it would never repay the labour required. Where the soil is Inclined to peat, this operation and abundant liming are the India. pensable preliminaries of cultivation. The ashes and the limo will produce vegetation and food for animals. These will produce dung to supply what the vegetation abstracts, and to assist also in the further decomposition of the peaty matter, converting it into vegetable mould.