What is called the yarn, or Surinam potatoe, is of more importance to the farmer, because with this vari ety he has an excellent assistant to his turnip crop, or rather a succedaneum, which is of material benefit when turnips are consumed. Perhaps this root may he culti vated with greater advantage than rum baga upon many soils, as the precariousness of ruta baga has been ac knowledged by almost every one who has treated upon the subject. It requires soil of the hest quality, and a large dose of rich dung, to ensure evee a middling crop of ruta baba; therefore it can never be generally nor profitably cultivated by common LIM( I'S. WC arc well aware, that a root of the same size is marl) of one-third more weight than one of turnips, and that, in point 01 nourishment there is also a very considerable dilrerenf e. Still, after all, when we look abroad, and ti iew the small crops that arc commonly raised, and take into accomo the superior care bestowed upon this mea, it must be acknowledged, that necessity, not profit, is the impelling cause of its culture.
On the other hand, yams present every advantage which can be got from ruta baga, and are not so pettish in their growth. Their cultm e is a matter of far les, difficulty, as such will grow upon soils where ruta baga would starve. They require less manure, and may be planted as late in the season as the other, thereby c na bling the farmer to bestow the like previous preparation upon the ground, the want of which is a general argu ment against ordinary potatoe husbandry. By taking them up in October or November, they may be safely housed, and the ground directly ridged up and sown with wheat. No doubt, ruta baga may be removed at the same period ; but it often happens that the root has not then reached maturity ; its growth being rarely im peded till frost sets in.
It is believed that very few crops of ruta baga, ex ceeding ten tons per Scottish acre, have been got in this country, and that many do not exceed one-half of that weight ; while, on the other hand, we are pretty certain that sixty bolls of yams, which amount exactly to twelve tons, may be got, were such planted upon land similar to what is usually assigned to ruta bag,a; and presume that the nutritive substance contained in a ton of each, is not materially different. Even under the supposition, that fifty bolls, or ten tons only, were gained, still the preference ought to he assigned to yams, on account of the reasons already mentioned.
If potatoes are ever to be extensively introduced as an article of fallow crop, it must be with a iew of or copying the place of ruta haga, or as the means of car rying on live stock, after turnips are consumed, till the grass season arrives. During the ordinary season of
winter feeding, neither potatoes nor ruta haga can be furnished to stock on the same terms with turnips ; though, when turnips are gone, the next best resource must be sought after. This, in our opinion, can be gained with more facility by raising yarns, which, as al ready said, are not so shy in growing, do not require s.) much manure, and thrive on soils where ruta haga would not yield a root much exceeding a common sized egg.
Though yarns arc not to be ranked in value with tur nips as an article of winter feeding, it deserves attention. that they may be successfully cultivated on soils physi cally unfit for the former root. In fact, the greatest crops of yams are procured from heavy lands; the soft kindly soils, generally considered most adapted to pota toe culture, being unfriendly to the growth, or rather to the productiveness of the variety which we arc recom mending (Waning of potatoes. After having detailed the me thod of cleaning beans so circumstantially, it appears unnecessary to enter at much length upon what is re quired for potatoes, because one and all of the green crops rc quire somewhat similar management, when cul tivated according to the drill system.—The only differ ence is, that hand-hoeing is necessary bc mixt the plants ; but in other respects every part of the cleaning process may be most successfully executed by the ho•se-hoe. Once for all, it may be remarked, that green crops of every kind arc greatly benefited by frequent hoeings, and that their growth, in smile measure, is regulated by the extent of labour bestowed on them. When treated in a slovenly manner, or left to fight with weeds, or even to encounter a firm soil, the plants are deprived of nou rishment, and unable to procreate their kind in due abundance ; on the contrary, when the soil is sufficiently stirred up, and kept free of weeds, nature will return a crop in direct proportion to the quality of the soil, and the quantity of manure bestowed upon it by the cultiva tor. Nature may be improved by art, but when her bounties are neglected, and not improved, she generally turns aside, and repays the contempt with interest.
Discaoc which affects potatoes. The disease which peculiarly affects potatoes, is called the curl, the real cause of which has not yet been, and probably never will be, ascertained. It seems to be one of these secrets of nature kept from the knowledge of mall ; and though many plausible and ingenious theories have been ()fiercd to the public concerning it, we are just as much in the dark with respec t to this abstruse subject, as when the evil was first discovered.