568 H U S B A 
ferent from various caufes, fuch marls mull be more or 
lefs pure, or contain greater or lefs proportions of calca¬ 
reous matter, according to fuch circumftances; in general, 
however, they contain a larger proportion than the ordi¬ 
nary forts of lime. In the fecond kind there is much clay 
ufually combined with the calcareous matter, from which 
circumftance it abl'orbs and retains moifture more ftrongly 
•than moll of the other kinds. The clayey forts of marl 
vary greatly in refpeft to their colours, being met with 
of a brown, blue, red, and yellow, tinge. The third 
fort, or ftone-mari, has different proportions of fand 
united with the calcareous matter and the clay, upon 
which depends the differences in regard to its hardnefs. 
•Where this fort of marl has a thin laminated ftruclure 
and flakey appearance, it is frequently denominated Jlate.- 
wiarl. From the portion of clay that is contained in 
thefe marls, they become capable of being gradually fatt¬ 
ened by the action of water, and ultimately fall down 
into tire powdery date. All marls contain 1 'ome portion 
or other of clay, in combination with the calcareous mat¬ 
ter, as has been long fince fhovvn, while in lime it is 
rnoflly land which is united with that fubftance. 
Notwithftanding thefe differences in the appearance and 
conftitution of marls, they all agree in being reduced 
into a pulverulent or powdeiy date, by expofure for fome 
.length of time to the influe-nce of the atmofphere, by 
which means they are rendered capable of being inti- 
fnately blended with the different materials of the foils 
upon which they are applied 5 but as this general property 
of failing -down into fmall particles, in confeauence of- 
the abforption of moifture and carbonic acid, or fixed air, 
from the furrounding atmofphere, is much greater in 
dome kinds of marl than others, it may caule home differ¬ 
ence in their utility as manures. Where fubftances of 
-this kind are laid upon land for the purpofe of Tupport- 
ing an immediate crop of either corn or grafs, there can 
'be little doubt but that the molt crumbly, or thole the 
molt readily reducible into a powdery ftate, are the molt 
proper; but, where they are laid on with the intention 
only of alfilting future crops, or of producing more lalt- 
ing effects, thole that are more hard, and lefs difpofed to 
fail into pieces, may be more advantageoully employed. 
The former feems to be Ihown to be the cafe, by the 
common obfervation of practical hulbandmen in marling 
•diftricts, that marl does not exert its full effects on the 
foil until it has been well mixed and incorporated with 
it by frequent aration, and by the practice of letting it 
remain fome time on the furface of the ground before it 
is turned down, from which it becomes much pulveriled 
and reduced 5 and the latter, by the circumltance of the 
harder forts of marl remaining a great length of time 
upon or within the ground, before they are fully decom- 
pofed or broken down. 
This kind of manure produces beneficial effects on 
molt forts of foil in its different forms; the fliell, ftone, 
and thole kinds of marl which abound molt with calca¬ 
reous earth, or which have fand in their compolition, are 
the moll adapted to the Itrong, ftiff, clayey, foils, as by 
-the infinuation of fuch matters they are not only rendered 
more light and friable, but a great part of the injurious 
moifture which they contained is removed. But thofe in 
which clay is considerably predominant are found more 
advantageous in the light, dry, lhndy, gravelly, and loamy, 
foils, as by fuch fubftances the defefts of lightnefs are re¬ 
medied, and the necelfary moifture in fome meafure pre- 
ferved. On the ftronger forts of loamy foil, clayey marl 
will moftly be improper, as it has much tendency to ren¬ 
der fuch forts of land more wet and adhefive, by which 
they may be greatly injured. Thefe have been found to 
be the effects refulting from the application of it even 
upon a temperate loam, in fome parts of Suffex. And 
befides it is fometimes apt to bring up coltsfoot, a weed 
which is difficult to be eradicated. 
In the quantity or proportion of thefe fubftances that 
b applied, there,is confiderable difference i* different dif- 
NDIY. 
tricls, a circumftance which, in fome degree, depends 
upon the nature of the foils ;, the heavy, clayey, or loamy, 
requiring fin general a much larger proportion than the 
light, fandy, or gravelly. The general quantity employ¬ 
ed may probably be eftimated at from about two to four 
or five cubic roods of fixty-four yards to the ftatute-acre, 
according to the ftate of the marl, and particular nature 
and condition of the grounds on which it is laid. It may, 
however, in many cales, be the molt advifable practice 
not-to apply too thick a-coveriug at one time, but to have 
recourle to light dreffings more frequently, as by fuch a 
method the fertility of the land may be better preferved 
and kept up, and the crops be rendered more abundant. 
This manure is employed both on lands in a courfe of 
tillage, and grafs-lands, from different feed-crops. On 
the former it is generally made ufe of as a preparation for 
barley, turnips, and other fimilar crops, or applied upon 
clover or other new lays, previous to their being ploughed 
up for wheat; in which modes of making ufe of it,“ the 
common prafitice is to leave it fpread out upon the fur- 
face for fome length of time before it is turned in, in or¬ 
der that it may be well reduced into a powdery form; 
for, the more perfeftly the marl is broken down and fpread 
out, the more effeftual it is found in promoting the growth 
of the crops. In its application in the latter cafe, it is 
frequently laid on in too large quantities, or left too long 
in its lumpy ftate ; from both which circumftances difad^ 
vantages are produced to the growth of the grafs, when 
either to be cut for hay or fed oft’ by cattle; as by the 
former, where the marl contains much of the argillaceous 
material, a kind of cruft is formed, that prevents its fprin°- 
ing, as happens where the ftiff mud of ponds, and fuch- 
like manures, are too thickly laid on lands ; and from the 
latter, the grafs is not only injured by the fmall clods, as 
is experienced where imperfe&iy-reduced clayey earth is 
applied, but the effefts of the manure are prevented from 
being fully exerted, on account of its not being well- 
broken, and carried down to the abforbent roots of the 
grafles, by the frequent rains that may take place after its 
application. 
Some farther attention feems likewife requifite in the 
ufe of this manure, as well as to the mode of cropping 
with it. When employed in large proportions, whether 
upon the heavier or lighter forts of land, a confiderable 
f'pace of time appears, from experience, to be required to 
elaple, before it can with advantage be had recourfe to 
again ; for, if this circumftance be not properly attended 
to, or too many white crops be fucceffively taken, a very 
great degree of exhauftion is foon produced, as has been 
experienced in many of the marling counties of England, 
and in Forfarfhire in Scotland. Thefe injurious confe- 
quences are, however, found to be eafily prevented, by 
adopting the alternating fyftem of corn and grafs, or other 
green crops. And it is probable, that by taking com 
and grafs-crops in fucceffion, or, after having one or two 
grain-crops, letting the land be laid down for two 
or three years with artificial graifes, the application of 
marl in fmall quantities might be more frequently re¬ 
newed, to the great advantage of the farmer, and the im¬ 
provement of the land. In l'ome of the places where this 
kind of manure is made ufe of, as in Lancalhire, fome- 
thing of this practice is adopted with much benefit. And 
when mixed with dung and other fubftances, in the form 
of compoft, it is generally found capable of being repeat¬ 
ed, at fhort intervals, with the moll beneficial. effetts. 
From thefe fafts it would therefore feem probable, that 
fuch injuries are rather to be al'cribed t;o the mode of 
cropping, than to the nature of the manure. Something 
may alio, perhaps, depend on the manner in which it is 
applied, as it has been found to be more efficacious when 
well mixed and incorporated with the foil, than where 
this has not been the cale ; and, as it has been found 
highly advantageous in promoting and bettering the con¬ 
dition of the grafs-lands in fome diftri&s, while in others 
it has been obje&ed to as injuring them, it is ftill farther 
1 probable 
