Marl is valuable as a manure in propor tion to the quantity of calcareous earth which it contains, which in some install ces amount to one half. When of this quality, it may be reg-arded as the most substantial of all manures, converting the weakest ground nearly into the most pro ductive. It is the best of manure for clay soils in which all agricultural writers are perfectly, agreed. - Before its application, the land should he cleared of weeds, and smoothed, that it may be evenly spread ; after which it shouldremain all winter on the smface. Its usefulness depends on its pulverization and close union with the soil to which it is applied. Frost, and a fre quent alternation of dryn ess and humidity, contribute greatly to reduce it to pow der on which account it should, as much and' as long- as possible, be exposed to their influence. The proper season for marling land is summer. The best grain for the first crop after marl is oats. But, whatever be the crop, the furrow should be always ebbed, as otherwise the marl, which is a heavy body, sinks to the bot tom of it.
Gypsum, or plaster of Paris, is com monly used in Switzerland and North America as a manure, and has been tied in this country with stated results of a very different description. Experiments, however, respecting its efficacy and ad vantages, do not appear yet to have been made with sufficient accuracy to justify a 'final opinion respecting it. In Cornwall and other counties, sea sand is laid upon the land in considerable quantities, and found extremely useful in softening stiff clays, and rendering them pervious to the roots of plants. Chalk, or powdered lime stone, will also answer this important end; and sand, together with lime perfectly extinguished, will, more effectually than any thing else, open its texture, and pre pare it for whatever is intended to be sown on it The true nourishment of vegetables consists of water, coal, salts, and differ ent kinds of earths, which are ascertained to be the only substances common to ve getables, and the soi Is i n which they grow. In favourable weather, grasses and corn absorb and perspire nearly half their weight of water every day. The great problem mith respect to manuring or fer tilizing- a soil appears to be, how to ren der coal soluble in water for the purpo ses of vegetation and to discover that composition of theadifferent earths, which is best adapted to detain the due pro portion of' moisture. With respect to the former, the fermentation of dung appears to be the best method hitherto discover ed; and as to the different kinds of earths to be applied for the improvement of particular soils, the experiments of' Mr. Kirwan, to whom the world is indebted for much elaborate-and ingenious analy sis on the subject, have led him to seve ral conclusions, which will be briefly no ticed. Clay soils, being defective in con stitution and texture, want the calcare ous ingredient, and coarse sand. The former is supplied by calcareous marl, and both are furnished by limestone gra vel. Marl and dung are still more bene ficial, as dung supplies the carbonaceous principl e. Sand, chalk, or powdered lime stone, will either of th ein answer this pur pose, though less advantageously. Coal ashes, chips of wood, burnt clay, brick dust, and even pebbles, may be applied with this view. For clayey loam, if defi cient in the calcareous ingredient, chalk is an excellent manure ; if in the sandy ingredient, sand is the obvious and easy remedy; a deficiency in both will be best supplied by siliceous marl, limestone gra vel, or effete lime with sand. The most effectual application for the chalky soils, which want both the- argillaceous and the sandy ingredients, is clayey or sandy loams. For chalky loam, the best ma nure is clay, because this soil is chiefly defective in the argillaceous ingredient.
Calcareous marl is the best manure for sandy soils. For sandy loams, chalk should be followed by clay ; and for vi triolic soils, lime, or limestone gravel, or calcareous clay, is peculiarly applicable.
Not only sea-sand, hut sea-weeds also, may be employed to considerable advan tage as manure. For lands on the coast it may be procured, not only in any quan tities, but at a trifling expense. The weeds of rivers are also extremely use ful for the same purpose. The refuse of slaughter-houses and oil cakes are well adapted to fertilize the soil, but in most situations not easily to be obtained at a reasonable rate.
In almost all circumstances, the indus try and ingenuity of the occnpier must be depended on for raising on the spot an ade quate quantity of dung for its manure ; and for this purpose it is expedient that, in such circumstances, as little as possi ble of the hay and straw raised upon the premises should be sold from them. This tenaciousness on the part of the farmer will prove the constant source of improve ment. With a view to turn his means of manure most advantageously- to account, he should draw into his farm yard, at the most leisurely season of the year, before the time of confining his cattle to fodder, as much marl, turf, thy mud, loam, and other applicable articles, as will cover its surface to the depth of twelve inches. If there be many hog-houses, stables, and cow-stalls, that are cleansed into the yard, on such spots these materials should be spread more thickly. Bog pests, if near at hand, should never be neglected. These pests may be regarded as vegeta ble dunghills, and their easy accessibility in this connection will be regarded as of extreme utility and consequence. Before foddering is begun, the whole yard should be well littered, for which stub ble, fern, and leaves, are ell adapted. No money laid out by the farmer is more wisely and successfully expended, than that which he employs in procuring, at a reasonable rate, great quantities of litter, by which his cattle are enabled to lie dry and warm, and the mass of manure which he raises is much larger and cheaper than he could procure in any other mode. Fern abounds in alkaline salts, and must therefore obviously produce very valna ble• dung: it requires, however, to be rotted well, and is more difficult to be so than straw. In woodlands, leaves may be collected at slight expense, and will make admirable litter and dung. In the neigh bourhood of marshes, rushes, flags, and coarse grass, may all be easily procured, and will be exceedingly serviceable. After these exertions and preparations, the farmer must strictly confine his cattle during the winter, not by tying them, as some have done, so as completely to prevent their roaming in the adjoining pastures. By thus confining all the cat tle upon straw, and turnips, and hay, as may be requisite, the necessary quantity of animal manure will be obtained to make the compost of the several ingredi ents ferment, rot, and turn to rich ma nure, while without these animal materi als, the heap might be large, but would be of little value. The draining from the yard should never run to waste, and, un less in extraordinary cases, such as ex tremely violent mins, this may be easily prevented. An excellent method for this purpose is the sinking a well in the low er part of the yard to fix a pump in ; by which the water may be conveyed along a trough to a large heap of marl, turf, chalk, •anci other appropriate materials, which, by a daily application of this li quor, will be of little less value eventu than a heap of dung of the same size.