MANURES.] AGRICULTURE 351 " 2. That even when land of this description is well fallowed and dunged, but not limed, though the dung augments the produce of the subsequent crop of grain, and of grass also for two or three years, its effects thereafter are no longer discernible either upon the one or the other. " 3. That when this land is limed, if the lime is kept upon the surface of the soil, or well mixed with it, and then laid down to pasture, the finer grasses continue in possession of the soil, even in elevated and exposed situations, for a great many years, to the exclusion of bent and fog. In the case of Grubbet-hills, it was observed, that more than thirty years have now elapsed. Besides this, the dung of the animals pastured upon such land adds every year to the luxuriance, and improves the quality of the pasture, and augments the productive powers of the soil when afterwards ploughed for grain ; thus producing upon a benty outfield soil effects similar to what are experienced when rich infield lands have been long in pasture, and which are thereby more and more enriched. 4. That when a large quantity of lime is laid on such land, and ploughed down deep, the same effects will not be produced, whether in respect to the permanent fineness of the pasture, its gradual amelioration by the dung of the animals depastured on it, or its fertility when afterwards in tillage. On the contrary, unless the surface is fully mixed with lime, the coarse grasses will in a few years regain possession of the soil, and the dung thereafter deposited by cattle will not enrich the land for subsequent tillage. " Lastly, It also appears from what has been stated, that the four-shift husbandry is only proper for very rich land, or in situa tions where there is a full command of dung ; that by far the greatest part of the land of this country requires to be continued in grass two, three, four, or more years, according to its natural poverty; that the objection made to this, viz., that the coarse grasses in a few years usurp possession of the soil, must be owing to the surface soil not being sufficiently mixed with lime, the lime having been covered too deep by the plough." Farmers Magazine, vol. xiii. p. CD. Section 11. Marl. Our remarks hitherto have had reference to carbonate of lime in that form of it to which the term lime is exclusively applied by farmers. But there are other substances fre quently applied to land which owe their value chiefly to the presence of this mineral. The most important of these is marl, which is a mixture of carbonate of lime with clay, or with clay and sand, and other compounds. When this substance is found in the proximity of, or lying under, sandy or peaty soils, its application in considerable doses is attended with the very best effects. The fen lands of England, the. mosses of Lancashire, and sandy soils in Norfolk and elsewhere, have been immensely improved in this way. In Lancashire, marl is carried on the mosses by means of portable railways at the rate of 150 tons, and at a cost of about 3 per acre. In the fens long trenches are dug, and the subjacent marl is thrown out and spread on either side at an expense of 54s. per acre. By this process, often repeated, of claying or marling, as it is variously called, the appearance and character of the fen lands have been totally changed, excellent wheat being now raised where formerly only very inferior oats were produced. As the composition both of peat and of clay marl varies exceed ingly, it is always prudent, either by limited experiment or chemical analysis of both substances, to ascertain the effect of their admixture. Lime is always present in those cases which prove most successful ; but an overdose does harm. Section 12. Shell-Marl. Under some mosses and fresh-water lakes extensive de posits of shell-marl are frequently found. It contains a larger percentage of lime than clay marl, and must be applied more sparingly. Section IZ.CJcalk. Throughout the extensive chalk districts of England, the practice of spreading this substance over the surface of the la ml has prevailed from the remotest times. In the case or fhe Lincolnshire Wolds, once as celebrated for desolate barrenness as they now are for high culture and smiling fertility, chalking was one important means of bring ing about this wonderful improvement, as it still is ia maintaining it. " The soil being but a few inches in depth, and often containing a large proportion of flints, naturally possesses very little fertility often being a light sand, not strong enough naturally to grow turnips so that the farmers were at first obliged to make a soil, and must now maintain its new-born productiveness. The three principal means by which this is done are the processes of chalking, and boning, and manuring ivith sheep. A dressing of 80 or 100 cubic yards per acre of chalk is spread upon the land, and then a crop of barley is obtained if possible, being sown with seeds for grazing. The fit-Ids are grazed with sheep two years, the sheep being at the same time fed with oil cake ; and then the land will be capable of producing a fine crop of oats. Bones are also used frequently for the barley crop, and when they first came into use were thrown upon the land in a chopped state, neither broken nor crushed, and as much as 40 or even 50 bushels per acre. The boning and sheep-feeding are in constant operation, but chalking is required only at intervals of a few years. On the western side of the Wold district, wherever the chalk adjoins the white or blue marl, an extensive application of it is made to the surface. Thus immense quantities of earth and stone have been added by manual labour and horse carriage to the thin covering of original soil ; and, besides this, the soil is being continually deepened by deep ploughing, the chalk fragments thus brought to the surface crumbling into mould." 1 In Dorsetshire "it is usual to chalk the land once in twenty years, the sour description of soil being that to which it is found most advantageous to apply it. The chalk is dug out of pits in the field to which it is applied, and it is laid on sometimes with barrows, but chiefly with the aid of donkeys. The first method costs 40s. an acre, the last 35s. when hire donkeys are used ; 20s. to 25s. where the donkeys are the property of the farmer. The chalk is laid on in large lumps, which soon break down by the action of frost and exposure to the weather. Chalk is occasionally burned and applied as lime, in which state it is preferred by many farmers, notwithstanding the additional cost of the burning." 2 Section 14. Shell-Sand and Limestone Gravel. On the western shores of Great Britain and Ireland are found great quantities of sand mixed with sea-shells in minute fragments. This calcareous sand is carried inland considerable distances, and applied to the land as lime is elsewhere. Limestone gravel is also found in various places and used in the same way. Section 15. Gypsum. Sulphate of lime or gypsum is considered an excellent top-dressing for clover and kindred plants. It is thought by some that the failure of red clover is to be accounted for by the repeated crops of that plant having exhausted the gypsum in the soil. Its application has been followed by favourable results in some cases, but has yet quite failed in others. It is applied in a powdered state at tho rate of two or three cwt. per acre when the plants are moist with rain or dew. Section 16. Burnt Clay. About fifty years ago burnt clay was brought much into notice as a manure, and tried in various parts of the country, but again fell into disuse. It is now, however, more exten sively and systematically practised than ever. Frequent 1 " Farming of Lincolnshire," by John Algernon Clarke ; Jour.tal of Royal Agricultural Society, xii. 331.
1 See Caird s English Agriculture, 1850 and 1851, p. 61.
