operation is carried on. But it may be neces- 

 sary to an impartial examination of the subject, 

 to inquire into the changes produced on the 

 substances subjected to the process of burning-, 

 when it is done with due precautions. 



In burning vegetable matter in an open fire, 

 the whole of the carbon is converted into .car- 

 bonic acid and flics off, leaving only some light 

 ashes containing the earthy matter and the salts 

 which the fire could not dissipate. The.se are 

 no doubt very powerful agents in promoting 

 vegetation, ^vhen they are added to any soil; 

 but they are obtained at a very gi-eat expen.se 

 of vegetable matter, which, by its decomposi- 

 tion in the earth, might also have afforded food 

 for vegetation. If the earth which is burnt with 

 the sods is of a cold clayey nature, the fire will 

 change it into a kind of sand, or brick-dust, 

 wliich is insoluble in water, and coirects the 

 too great tenacity of clays, by converting them 

 more or less into loams. This is so well known 

 that clay is often dug out of the subsoil to be 

 partially burnt. On stiif clay soils, therefore, 

 there is a double advantage in paring and burn- 

 ing, that of the vegetable ashes and of the burnt 

 clay. When the fire is so managed that the 

 vegetable matter is only partially burnt, the oily 

 and inflammable portions being" converted into 

 vapor by the fire without being destroyed, and 

 absorbed by the earth, the effect produced is 

 only to impregnate the earth with minute parti- 

 cles of -matter, readily converted into the con- 

 stituent parts of vegetables. The earth is the 

 mere recipient of these particles, which are held 

 in its pores, as water ia in a sponge, ready to be 

 let loose to any substance which has the power 

 of attracting them. The moisture, which the 

 dry earth will also absorb from the atmosphere 

 if no rain should fall, is retained and increased 

 by the effect of the salts with which it is im- 

 pregnated. It is uniformly observed that turnip- 

 seed, which in most soils will not vegetate 

 without heavy dews or rains, if sown in dry 

 weather, scarcely ever fails to spring up in the 

 ashes of a soil that has been pared and burnt. 

 May not this be ascribed to these particles, 

 which have been taken up by the earth in the 

 operation of slow combustion, absorbing mois- 

 ture from the air, and giving it out to the seed 

 which has been sown ? It does this better than 

 a heavy shower would: a heavy shower soaks 

 the ground for a .short time, and swells the seed : 

 but, if it be succeeded by a hot sun, the water 

 evaporates so rapidly that the seed loses its 

 moisture, and vegetation stops. The earth, 

 which attracts moisture from the air, keeps it, 

 its absorbent nature preventing the evaporation ; 

 and it furnishes it gradually to the vegetating 

 seed as it is required. The wonderful effect of 

 peat-ashes on young clover may be explained 

 on the same principle, and probably also that of 

 gj'psum. There can be no doubt, then, that 

 considerable advantages may result from the 

 operation of paring and burning the surface of 

 clays. But what is lost and destroyed in the 

 operation .' All that escapes in the shape of 

 gas or vavor. The gas will probably be car- 

 bonic acid ; for this is formed by the combustion 

 of charcoal. We know that hot lime has a verv- 

 strong attraction for this substance, which it 

 fixes in a solid state, becoming a carbonate of 

 lime ; and we have no reason to think that it 

 parts widi it to the roots of plants. But other 

 earths may absorb carbonic acid: without having 

 so gi-eat an attraction for it, and let it loose to 

 water, with whicli -it is known to combine in 

 M02) 



certain proportion.s, and to be thus carried into 

 the vessels of growing plants by the attraction 

 of the roots. If this should prove to be the 

 case, we may account for the great effect of 

 burnt sods in promoting vegetation. 



The principal objection to burning is, that it 

 destroys a great portion of vegetable matter. 

 But this is a fact to be proved, and is perhaps 

 rashly taken for granted. When vegetable 

 matter decays in the earth, it loses much of its 

 substance, which is converted into volatile mat- 

 ter, and flies off into the atmosphere. It is 

 possible that thus more is lost during the time 

 tliat the slow decay goes on, dian even in burn- 

 ing with due precautions. This is a fact which 

 may be difficult to a.scertain ; but it is not im- 

 possible ; and therefore the assumption of the 

 contrary requires to be founded on some proof 

 or experiment. The earthy portion of the soil 

 may be diminished by driving out the water 

 which it held, as is manifest in burning clay, 

 and it shrinks into a smaller space ; but there is 

 as much earthy substance as before, and this 

 substance is improved by the burning. It ap- 

 pears, then, that a clay soil may be pared and 

 burnt, without its real substance being dimin- 

 ished ; and if its texture is improved, it becomes 

 more fertile by the operation. 



Burning clay soils is in fact something analo- 

 gous to liming. Lime dissolves the vegetable 

 matter, and enables its elements to enter into 

 new combinations; but if no new vegetable 

 matter be added to re.store what is exhausted 

 by vegetation, liming, as well as paring and 

 burning, is detrimental in the end. Many ex- 

 perienced farmers pare and bum the soil on the 

 edges of their ditches and on the banks on 

 which the hedges grow, because they thereby 

 extemiiuate 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 pro- 

 duced 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 tliis case we do not 

 hesitate to recommend it on all cold clay soils 

 where rank weeds are apt to spring up. and 

 coarse gi-asses take the place of the better sorts 

 which have been sown. The proper time to 

 pare and bum 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 allow- 

 able for the .sod if the soil is very- stiff and poor, 

 and as thin as possible in a better soil. It should 

 be done with a breast-plow or paring-iron by 

 manual labor. 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 eslab- 

 lished itself, all the apertures should be carefidly 

 clo.sed. Wherever any .smoke breaks out, a 

 fresh sod should be immediately jjut over it ; a 

 heap containing a small cartload 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 fonn hard lumps, and even 

 %ntrify; 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 color, 

 it is a good sign ; for the iron in the earth has 

 been converted into a peroxide, which is per- 

 fectly innocent in its effects on vegetation ; 



