206 



FARMERS' REGISTER 



[No. 4 



adopted in Great Britain, barley straw, owing per- 

 haps to its being cut early, was used as food for 

 cattle in preference to others, as cattle could eat it 

 uncut more readily than the harder straws. Wheat 

 or oat straw is now preferred when it is to be con- 

 verted into chaiT, or cut fine for mixing with hay 

 or roots. There arc varieties of barley found in 

 the shops, pearl and Scotch, both of which are 

 prepared by divesting the kernel of its husk in 

 mills, resembling in some degree the rice-mills of 

 the south ; and in the case of the pearl barley, the 

 grinding or rubbing is continued until the berry 

 assumes a smooth round form. Few articles are 

 more nutritious, or bettor adapted to the stomachs 

 of the weak or the valetudinarian. 



From tlie London and Edinl)Uigli Pliilnsoplncal Magazine, 

 ON THE FORBIATION OF IMOULD. 



B]i Charles Darwin, Esq., F. G. S. 



The author commenced by remarking on two 

 of. the most striking characters by Avhich the su- 

 perficial layer of earth, or, as it is commonly call- 

 ed, vegetable mould, is distinguished. These are 

 its nearly homogeneous nature, although overly- 

 ing difl'erent kinds of subsoil, and the uniform 

 fineness of its particles. The latter fact may be 

 well observed in any gravelly country, where, al- 

 though in a ploughed field, a large proportion of 

 the soil consists of small stones, yet in old pasture- 

 Jand not a single pebble will be found within some 

 inches of the surface. The author's attention 

 was called to this subject by Mr. Wedgwood, of 

 Maer Hall, in Staffordshire, who showed him 

 several fields, some of which, a few years before, 

 had been covered with lime, and others with burnt 

 marl and cinders. These substances, in every 

 case, are now buried to the depth of some inches 

 beneath the turf. Three fields were examined 

 with care. The first consisted of good pasture 

 land, which had been limed, without havinir been 

 ploughed, about twelve years and a half before: 

 the turf was about half an inch thick; and two 

 inches and a half beneath it was a layer, or row, 

 of small aggregated lumps of the lime, forming, at 

 an equal depth, a well-marked white line. The 

 soil beneath this was of a gravelly nature, and 

 diflered very considerably from the mould nearer 

 the surface. About three years since cinders were 

 likewise spread on this field. These are now bu- 

 ried at the depth of one inch, forming a line of 

 black spots parallel to, and above, the white layer 

 of lime. Some other cinders, which had been 

 scattered in another part of the same field, were 

 either still lying on the surface, or entangled in the 

 roots of the grass. The second field examined 

 was remarkable only from the cinders being now 

 buried in a layer, nearly an inch thick, thfee in- 

 ches beneath the surface. This layer was in parts 

 so continuous, that the superficial mould was only 

 attached to the sub-soil of red clay by the longer 

 roots of the grass. 



The history of the third field is more complete. 

 Previously to fifteen years since it was waste land; 

 but at that time it was drained, harrowed, ])lough- 

 cd, and well covered with burnt marl and cinders. 

 It has not since been di.stuibed, and now supports 

 a tolerably good pasture. The ieclion here was, linchco and a half had been well digested 



turf half an inch, mould two inches and a half) a 

 layer one and a half inch thick, composed of frag- 

 ments of burnt marl (conspicuous from their bright 

 red color, and some of considerable size, namely, 

 one inch, by a half broad, and a quarter thick,) 

 of cinders, and a ihw quartz pebbles mingled 

 with earth; lastly, about four inches and a half 

 beneath the surlace was the original, black, peaty 

 soil. Thus beneath a layer (nearly four inches 

 thick) of fine particles of earth, mixed with some 

 vegetable matter, those substances now occurred, 

 which, fifteen years before, had been spread on 

 the surface. Mr. Darwin stated that the appear- 

 ance in all cases was as if the fragments had, as 

 the farmers believe, worked themselves down. 

 It does not, however, appear at all possible, that 

 either the powdered hnie or the fragments of burnt 

 marl and the pebbles could sink through compact 

 earth to some inches beneath the surface and still 

 remain in a continuous layer. Nor is it probable 

 that the decay of the grass, although adding to 

 the surlace some of the constituent parts of the 

 mould, should separate, in so short a time, the fine 

 from the coarse earth, and accumulate the former 

 on those objects which bo lately were strewed on 

 the surfiice. Mr. Darwin also remarked, that 

 near towns, in fields which did not appear to have 

 been ploughed, he had often been surprised by 

 finding pieces of pottery and bones some inches 

 below the turf. In a similar manner on the 

 mountains of Chili he had been perplexed by no- 

 ticing elevated marine shells, covered by earth, in 

 situations where rain could not have washed it on 

 them. 



The explanation of these circumstances, which 

 occurred to Mr. Wedgwood, although it may, at 

 first, appear trivial, the author did not doubt is the 

 correct one, namely, that the whole is due to the 

 digestive process, by which tiie common earth- 

 worm is supported. On carefully examining be- 

 tween the blades of grass in the fields above de- 

 scribed, the author found, that there was scarcely 

 a space of two inches square without a little heap 

 of the cylindrical castings of worms. It is well 

 known that worms swallow earthy matter, and 

 that having separated the serviceable portion, they 

 eject, at the mouth of their burrows, the remain- 

 der in little intestine-shaped heaps. The worm 

 is unable to swallow coarse panicles, and as it 

 would naturally avoid pure lime, the fine earth ly- 

 ing beneath either the cinders and burnt marl, or 

 the powdered lime, would, by a slow process, be 

 .removed, and thrown up to the surlL^ce. This 

 sup|)osition is not imaginary, lor in the field in 

 which cinders had been spread out only half a 

 year before, Mr. Darwin actually saw the cast- 

 ings of the worms heaped on the smaller fi-ag- 

 ments. Nor is the agency so trivial as it, at first, 

 mifjht be thought; the great number of earth- 

 worms (as every one must be aware, who has 

 ever dug in a grass-field) making up for the in- 

 significant (juantity of work each performs. 



On the above hypothesis, the great advantage 

 of old pasture land, which farmers are always 

 particukirly averse from breakmgup, is explained; 

 lor the worms must require a considerable length 

 of time to prepare a tliick stratum of mould, by 

 thoroughly mingling the original constituent parts 

 of tlie soil, ao well as the manures added by man, 

 In the peaty field, in fifteen years, about three 

 " "" ■ ■ It is 



