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i ‘THE sot, - 27 
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cidentally washed down upon, or purposely brought to it. In fields, & 
and uncultivated place the -soil is almost as hard, and as 
coarse in its s texture, as the sub soil on which it rests; but in gardens 
which have been long in cultivation, the soles sail becomes so 
_ thoroughly pulverized by frequent diggings, and so mixed with the ® 
» Manure and decayed vegetables which have been added to it from + 
time to time, that it is changed imto the soft, light, fine, powdery 
substance, called garden-mould. If the sub-soil be naturally porous 
or well drained, this mould, however rich it may be made by the 
addition of decayed vegetable matter or animal manure, will always 
continue friable; and as long as it does so, it will be fitfor the 
growth of plants: but if no vent be allowed for the escape of the wa- 
ter, and it be continually enriched with manure, it will be changed 
in time into the black slimy substance that has gbeem already 
described. z 
Surface-soil is called peat-earth when it is composed of decayed 
vegetable matter, which has become partially decayed by time and 
immersion in water, but whichis not thoroughly decomposed. As 
this kind of earth cannot exist without abundance of stagnant mois- 
ture, it is almost always found on a clayey sub-soil, which prevents 
the water which falls upon it from escaping. Peat-earth has a 
spongy elastic feeling when trodden upon, arising from the quantity 
of water that it holds, and it can only be rendered fit for cultivation 
by draining ; or depriving it in some other manner of its superabun- 
dant moisture. In its elastic state it is what is called in Scotland a 
moss, and in England a peat-bog. Should the water, instead of being 
afforded a vent by drainage, be suffered to accumulate for many 
years, till it completely liquefies the peat, the soil becomes what is 
called a morass, or quagmire; and it can no longer be trodden on, as 
it will engulf any substance resting upon it. A still further accumu- ‘ 
lation of water will, in the course of years, cause the bog to burst its 
bounds, and overflow the surrounding country; as the Solway- 
moss did many years ago, and as bogs in Ireland have done frequent- 
ly. An excess of vegetable matter on a sandy or gravelly sub-soil, 
differs from the common black-peat in retaining less water; and in 
being mixed with a portion of the primitive earth, which, from its 
loose texture, becomes easily detached from the sub-soil and mixes 
with the surface-soil; which, when in this state, is called heath 
mould... . “ 
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