On the Manuring of Grass Land. 225 



as rest upon clay. That roots do die annually and form A'aluable 

 I'ertilizing matter for subsequent growth is indubitable, and I only 

 <;ontend that they do not do this in such quantity as to supersede 

 t!ie use of manure, which they would do if they really formed the 

 ■thick layer of (so-called) vegetable soil found in fields of old grass. 

 Whence then can we derive the fine surface-mould, so different 

 5n physical characters from the original soil of the field in which 

 it is found ? Mr. Darwin's explanation in a paper on mould 

 appears both clear and conclusive : — 



" The aiithor commences by observing two of tlie most striking characters by 

 -which the siiperficial layer of earth, or, as it is commonly called, vegetable 

 mould, is distinguished. These are its nearly homogeneous nature, although 

 overlying different kinds of subsoil, and the uniform fineness of its particles. 

 The latter fact may be well observed in any gravelly countrj', where, although in 

 a ploughed field, a large proportion of the soil consists of small stones ; yet in 

 old pasture land not a single pebble v^'ill 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 

 €e\Y 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 con- 

 sisted of good pasture-land which had been limed M'ithout having 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 

 ^g.jregated lumps of the lime, forming at an equal depth a well-marked white 

 line. The soil beneath this was of a gravelly nature, and differed very con- 

 ■siderably from the mould nearer the surface. About three years since, cinders 

 were likewise spread on this field ; these are now buried at the depth of an 

 incli, 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 

 sair.c field, were either still lying on the surface or entangled in the roots of 

 tlie grass. The second field examined was remarkable only from the cinders 

 being now buried in a layer nearly an inch thick, three inches beneath the sur- 

 face. This layer was in parts so continuous that the superficial mould was 

 ^uly attached to the subsoil 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, ploughed, and 

 well covered with burnt marl and cinders. It has not since been disturbed, and 

 now siipports a tolerably good pasture. The section here was turf half an inch, 

 mould two inches and a half, a layer one and a half thick, composed of fragments 

 of ijurnt marl (conspicuous f^rom their bright red colour and some of considerable 

 size, viz., an inch by half an inch broad and a quarter thick), of cinders and a 

 few quartz pebbles mingled with earth ; lastly, about four inches and a half 

 Tjcneath the surface 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 

 jspread on the surface. Mr. Darwin stated that the appearance in all cases was 

 .IS if the fragments had, as the farmers believe, worked themselves down. It 

 <locs not, however, appear at all possible that either the powdered lime 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 surface some of 

 the constituent parts of the mould, should separate in so short a time the fine 

 from the coarse earth, and accumiilate the former on those objects which so 

 Lately were strewed on the surface. Mr, Darwin also remarked, that near 

 VOL, XIX. Q 



