MANURE. 
3)4 
this can be effected. Manures therefore can aft only'by 
furnilliing folid or gafeous matters, capable of being dif- 
1'olved by water; for fuch fubftances as pnfs off into the 
atmofphere in a gafeous form are foon diifufed through it 
and loft. From 1 'ome direCt experiments, he is led to 
think that many foluble vegetable fubftances pafs un¬ 
changed into the roots of plants, like the colouring mat¬ 
ter of madder, which is known to tinge them red; and 
many fubftances, poifonous to vegetables, are neverthelefs 
abforbed by them. Mucilaginous, gelatinous, faccharine, 
oily, and extractive, fluids, are fubftances that, in their 
Unchanged ftates, contain all the principles neceflary to 
vegetation ; thefe fubftances, however, can leldom be ap¬ 
plied in their pure forms; and vegetable manures, befides 
thefe, ufually contain a great excefs of fibrous and infa¬ 
llible matter; which mult undergo chemical changes, 
before they can become the food of plants. The author 
then proceeds to confider the nature of thefe changes, the 
caufes that occafton them, and the products which they 
afford. If vegetable matters, which contain ftarch, fugar, 
mucilage, or other compounds foluble in water, be moif- 
tened, and expofed to air, in a temperature from 55° to 
8o°, the oxygen of the air will difappear, and carbonic 
acid be formed ; heat will be produced ; and carbonic 
acid, gafeous oxyd of carbon, and hydrocarbonate, be 
given off; a dark-coloured liquor, of a fourifh or bitter 
tafte, will likewife be formed ; and, if the procefsgo on for 
a fufficient time, nothing folid, except earthy and faline 
matter, coloured by charcoal, will remain. The dark li¬ 
quor contains acetic acid ; and, if albumen or gluten ex- 
iited in the materials, it then likewife contains volatile 
alkali. The pure woody fibre refills putrefaction moft ; 
but its texture is at length broken down, and it is ren¬ 
dered foluble by mixture with other elements. Animal 
matters, under fimilar circumftances, decompofe more ra¬ 
pidly, and carbonic acid and ammonia are formed dur¬ 
ing their putrefaction ; foetid compound elaftic fluids are 
given off, and likewife azote; dark-coloured acid and oily 
fluids efcape, and leave a refiduum of falts and earths 
mixed with carbonaceous matter. 
From this defcription of the nature of the fubftances 
employed as manures, the products which they yield un¬ 
der decompofition, and their ufe in nourilhing plants, it 
is evident, that, when they confilt principally of matter 
foluble in water, their fermentation or putrefaction fhould 
be prevented as much as poftible, thefe proceffes being 
ufeful only when the manure confifts chiefly of vegetable 
or animal fibre. All green fucculent plants readily fer¬ 
ment ; and, when intended for manure, cannot be ufed 
too foon after their death. The fame remark applies to 
fea-weed, which, in the weft of England, is always ufed 
as frefti as it can be procured. Dry ftraw of all kinds is 
generally fubmitted to fermentation before it is employ¬ 
ed ; but it may be doubted whether the practice fhould 
be indifcritninately adopted. It is rendered more ma¬ 
nageable, indeed, by undergoing this procefs ; but there 
is likewife a great lofs of nutritive matter. The author 
fuggefts, therefore, whether ftraw might not be more eco¬ 
nomically applied, if chopped fmall, and kept dry, till, 
it is ploughed in for the ufe of the crop. In this cafe, 
though its operation might be more flow, its effeCt, it is 
faid, would be more lafting. Mere woody fibre, it is add¬ 
ed, feems to be the only vegetable matter that requires 
fermentation to render it nutritive to plants. 
Without calling in queftion the general correCtnefs of 
the theoretical view's here advanced, we may be permitted 
to fay, that, in practice, they muft be received with much 
caution ; and, in many fltuations and circumftances, muft 
undergo very confiderable modification. It is not enough 
to confider merely the condition of the manure : we muft 
alfo direct our attention to the nature of the foil and the 
climate, the kind of crop, and the feafon of the year in 
which the manure is applied. Little benefit, for exam¬ 
ple, could be derived from ftraw inferted in the dry ftate 
luggefted by our author, unlefs the foil not only were 
in that condition, and poflefied that degree of fertility, re- 
quifite to begin and carry on, with fufficient rapidity, the 
decompofition or rotting, in the ftraw itfelf, but to fuftaira 
alfo the growth of the cultivated plants, till fuch decotn- 
pofition was duly brought about. It is only in the richer 
lands, thofe ftored with a good proportion of decompos¬ 
ing vegetable or animal remains, that fuch a raw material 
could be ufed with advantage, or even with fafety ; and 
the practice of employing fuch unreduced manure is not 
to be recommended, and is indeed feldom adopted, in poor 
foils, efpecially if fuch are damp or wet-bottomed, or he 
in a cold, elevated, or moift, fituation. The ufe of rough 
ftrawey manure, mentioned by Mr. Marfliall, in his Rural 
Economy of Norfolk, more than twenty years ago, as al- 
moft peculiar to Norfolk, may fuit with the low, warm, 
rich, foils of that diftriCt, but would by no means anfwer 
for foils of an oppofite defcription ; and the Norfolk prac¬ 
tice, in this refpeCty is little followed in other parts of 
England. But, while we thus objeCt to the practice of 
ufing dung in fo recent a ftate, except in foils and fitua- 
tions of a peculiar defcription, we muft alfo exprefs our- 
felves adverfe, in general, to the contrary practice of em¬ 
ploying it in a completely rotted ftate. From obierva- 
tion, and fo far as the experience of the moft correCt 
farmers goes, it would appear that there is a middle ftate 
of decompofition, which, in general, is preferable to the 
practice of ufing the ftraw either totally unreduced, or, 
as it were, completely rotted and diffolved. Dr. Fenwick, 
in an effay on fold-yard manure, printed in 1798, ftates, 
on the authority of one of the moft experienced and in¬ 
telligent farmers in his diftriCt, that half-rotted, litter, if ap¬ 
plied to land duly prepared to receive it, and ploughed 
and harrowed in immediately, is of more advantange than 
it would be if kept at the farm-ftead until thoroughly 
rotted. This ftate or condition of manure, and mode of 
ufing it, feems the moft generally applicable to different 
foils and fltuations; and to combine, therefore, in the 
greateft attainable degree, the prefervation of its moft 
eflential qualities with the fecurity of its moft beneficial 
operation. 
The objections to the ufe of greatly-fermented dung 
are, that, in bringing it into the ftate of Jhort muck, both 
fluid and gafeous matters efcape; fo that the dung is re¬ 
duced, fays our author, one-half, or two-thirds, in weight; 
the elaftic matters that efcape, are principally carbonic 
acid, hydrocarbonate, and ammonia, which the author 
found, by experiment, to be ufeful to vegetation, when 
introduced into the foil in which plants grew—a fad long 
ago afcertained by the very able and enlightened profel- 
for of agriculture in the Univerfity of Edinburgh. To 
prevent or check exceflive fermentation in a dung-heap, 
it is recommended that the mafs be preferved dry, kept 
cool, and defended from the contad of air. If a thermo¬ 
meter, plunged into the heap, does not rife to above ioo° 
Fahrenheit, there is little danger of much aeriform matter 
flying off; if the temperature is higher, the dung fhould 
be immediately turned, or mixed. Dung, if preferved for 
any time, fhould, as much as poffible, be defended from 
the fun; and the floor on which it is heaped, fliouid be 
paved with flat ftones, having a little inclination from each 
fide towards the centre, where a drain fhould be formed 
leading to a fmall well, by which any fluid matter may 
be collected for the ufe of the land. 
Animal fubftances, in general, require no chemical pre¬ 
paration, to fit them as manures for the foil ; it is only 
neceflary that they be duly blended with the earthy con- 
ftituents in a proper ftate of diviiion. If dead animals, 
as horfes and dogs, inftead of being left expofed to conta¬ 
minate the air, were covered over with five or fix times 
their bulk of foil mixed with one part of lime, and fufi¬ 
fe red to remain a few months, they would undergo de¬ 
compofition, and impregnate the foil with foluble mat¬ 
ters, fo as to render the mafs an excellent manure. Pil¬ 
chards, in Cornwall, are mixed with fand and foil, to pre¬ 
vent them from railing too luxuriant a crop ; and thus 
form an excellent manure, the effeCts of which are per¬ 
ceived for feverai years. And we may add, that, in ad- 
3 dition 
