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by frequently exposing new surfaces to the influence of thesun and air, to bring into vegetation the innumerable seedsof weeds contained in the soil, which are destroyed by thesubsequent operations of the fallow process. It is believedlikewise, that the soil acquires some accession of vegetativepowers by means of this process •, perhaps by the successivedestruction and consequent putrefaction of these crops ofweeds, forming a species of manure in the soil, and combin-ing with an absorption of some elementary principles fromthe atmosphere. The destruction of weeds is a palpable andobvious effect of fallow to every attentive observer; but themelioration of the soil, by the chemical influences of the atmos-phere, belongs to theoretic reasonings and deductions, whichare not perhaps sufficiently within the boundaries of our pre-sent knowledge. This much is however certain, that the soil,after a well-wrought fallow, has a mellow and fertile appear-ance familiar to every experienced husbandman, while thatwhich has only beep ploughed up after carrying repeatedgrain crops, or which has been carelessly and inefficientlyfallowed, has a close, coarse, and sterile appearance to theeye. The difference between the crops produced on landmanaged in these several manners, is not less distinct and re-markable •, as, all other things being equal, the well fallowedsoil produces a healthy, vigorous, and abundant crop of grain,comparatively free from weeds ; while the crop produced onthe other, is weak and scanty, and often overwhelmed by amultiplicity of weeds, disgraceful to the cultivator, and inju-rious to his interest.
However strongly disposed, from experience and analogy,to recommend the use of well conducted fallow on all soils fit-ted for its application by their nature and consistence, thereare certainly some soils which do not require this process, inthe strictest application of the term ; as on all light free soilsthe turnip husbandry, to be described hereafter, is perfectlysufficient for all the beneficial purposes to be derived fromfallowing, and is indeed a real and efficacious fallow process.