agriculture. 
nature of the lands, which, if strong, will 
easily bear a hundred bolls per acre, while 
thin and gravelly ones will require only 
thirty or forty, and upon meadow ones 
fifty or sixty will be found sufficient. 
Marl is valuable as a manure in propor- 
tion to the quantity of calcareous earth 
which it contains, which in some instances 
amounts to one half. When of this qua- 
lity it may be regarded as the most sub- 
stantial of all manures, converting the 
weakest ground nearly into the most pro- 
ductive. It is the best of manure for clay 
soils, in which all agricultural writers are 
perfectly agreed. Before its application, 
the land should be cleared of weeds, and 
smoothed, that it may be evenly spread ; 
after which it should remain all winter on 
the surface. Its usefulness depends on its 
pulverization and close union with the soil 
to which it is applied. Frost, and a fre- 
quent alternation of dryness and humidity, 
contribute greatly to reduce it to powder, 
on which account it should, as much and 
as long as possible, be exposed to their in- 
fluence. The proper season for marling 
land is summer. The best grain for the 
first crop after marl is oats. But, whatever 
be tire crop, the furrow should be always 
ebbed, as otherwise the marl, which is a 
heavy body, sinks to the bottom of it. 
Gypsum, or plaister of Paris, is commonly 
used in Switzerland and North America as a 
manure, and has been tried in this country 
with stated results of a very different des- 
cription. Experiments, however, respecting 
its efficacy and advantages do not appear 
yet to have been made with sufficient accu- 
racy to justify a final opinion respecting it. 
In Cornwall, and other counties, sea sand is 
laid upon the land in considerable quantities, 
and found extremely useful in softening stiff 
clays, and rendering them pervious to the 
roots of plants. Chalk, or powdered limestone, 
will also answer this important end ; and sand, 
together with lime perfectly extinguished, 
will more effectually than any thing else 
open its texture, and prepare it for what- 
ever is intended to be sown on it. 
The true nourishment of vegetables con- 
sists of water, coal, salts, and different kinds 
of earths, which are ascertained to be the 
only substances common to vegetables, and 
the soils in which they grow. In favour- 
able weather, grasses and corn absorb and 
perspire nearly half their weight of water 
every day. The great problem with respect 
to manuring or fertilizing a soil, appears to 
be, how to render coal soluble in water for 
the purposes of vegetation, and to discover 
that composition of the different earths 
which is best adapted to detain the due pro- 
portion of moisture. With respect to the for- 
mer, the fermentation of dung appears to be 
the best method hitherto discovered; and as 
to the different kinds of earths to be applied 
for the improvement of particular soils, the 
experiments of Mr. Kirwan, to whom the 
world is indebted for much elaborate and 
ingenious analysis on the subject, have led 
him to several conclusions, which will be 
briefly noticed. Clay soils being defective 
in constitution and texture, want the calca- 
reous ingredient, and coarse sand. The for- 
mer is supplied by calcareous marl, and 
both are furnished by limestone gravel. 
Marl and dung are still more beneficial, as 
dung supplies the carbonaceous principle. 
Sand, Chalk, or powdered limestone will 
either of them answer this purpose, though 
less advantageously. Coal ashes, chips of 
wood, burnt clay, brick-dust, and even peb- 
bles, may be applied with this view. For 
clayey loam, if deficient in the calcareous 
ingredient, chalk is an excellent manure ; if 
in the sandy ingredient, sand is the obvious 
and easy remedy : a deficiency in both will 
be best supplied by siliceous marl, limestone 
gravel, or effete lime with sand. The most 
effectual application for the chalky soils, 
which want both the argillaceous and the 
sandy ingredients, is clayey or sandy loams. 
For chalky loam, the best manure is clay, 
because this soil is chiefly defective in the 
argillaceous ingredient. Calcareous marl is 
the best manure for sandy soils. For sandy 
loams, chalk should be followed by clay; and 
for vitriolic soils, lime, or limestone gravel, or 
calcareous clay, is peculiarly applicable. 
Not only sea-sand, but sea-weeds also 
may be employed to considerable advantage 
as manure. For lands on the coast it may be 
procured, not only in any quantities, but at 
a trifling expense. The weeds of rivers are 
also extremely useful for the same purpose. 
The refuse of slaughter-houses and oil cakes 
are well adapted to fertilize the soil, but in 
most situations not easily to be obtained at 
a reasonable rate. 
In almost all circumstances the industry 
and ingenuity of the occupier must be de- 
pended upon for raising on the spot an ade- 
quate quantity of dung for its manure, and 
for this purpose it is expedient that, in such 
circumstances, as little as possible of the 
hay and straw raised upon the premises 
should be sold from them. This tenaci- 
ousness on the part of the farmer will 
