Mr. Young mentions a lecture he had read to the Board of Agriculture, "on the means by which a farm can be made, by a right proportion of all the products, to support itself, without foreign assistance, in a state of high fertility, a question depending on the quantity or weight of dung resulting from the consumption in litter of a given weight of straw." This lecture I have not seen. But he considers the question as successfully decided, in Mr. Arbuthnot's practice, in the following manner; 134 sheep and 30 lambs were turnip fed, in a pen on a headland, well littered with straw: in six weeks they required nearly six tons of straw [to give them clean and comfortable beds:] and in that time made 40 tons of dung, equal to that brought from London [stable dung it is to be presumed.] So every ton of litter produced near seven tons of dung.--But this weight must have been obtained chiefly by the earth of the headland absorbing the urine, of which, when fed on turnips, sheep make great quantities, and being finally mixed with their dung and litter. This recital reminds me of the recommendation, in my address to this Society, in May, 1818, to carry earth into the barn yard, once in every two weeks, from spring to autumn; adding to every layer of earth a coat of litter. I should then have advised a plentiful spreading of litter, had I not known that our courses of husbandry in Essex yielded very little straw.
In the same communication to the Society, I presented my ideas on the proper application of manure; to wit, _always to bury it up quickly, when carried to the field_, to prevent great loss by its exposure to the sun and air; remarking, that the essence of manure was lost, not by _sinking_ into the earth below the roots of cultivated plants, but by _rising_ into the atmosphere, and so fleeing away. Here, also, I have the satisfaction of seeing the theory I had formed nineteen years ago (in the manner suggested in that communication) supported by the opinions and practices of such eminent agriculturists as Messrs. Arbuthnot and Ducket. After noticing Arbuthnot's cultivation of madder, an article requiring a rich soil and extremely deep tillage, Mr. Young says, "there was one circumstance in his management, which, being applicable to more important articles, merits a more durable attention; this is, the depth to which he ploughed in the dung: his tillage went to that of eighteen inches; and he conceived there was no danger of losing, by this circumstance, either _vegetable_ or _animal_ manures, as _their_ tendency, contrary to all _fossil_ ones, was not to _sink_, but to _rise_ in the atmosphere." Fossil manures are lime, marl, plaster of Paris, and other substances dug out of the earth, which increase the productive powers of soils.