Causes of Fertility or Barrenness of Soils. 
179 
found in this country, exclusive of those formed by alluvial and 
drift deposit. As before stated, they present great variety of 
colour, texture, and physical properties, and consequently every 
grade of fertility from pure sand, which is perfectly barren, to 
the richest sandy loams. As a class, they may be termed free- 
working, porous, warm, dry, and quick soils ; but too frecjuently 
destitute or deficient in those important substances which are 
necessary to ensure the maturity of a crop. The very poorest 
are capable of great improvement by the addition of clay and 
lime ; though, when the sand is coarse-grained, it is to be feared 
that these substances would in time pass away, and be lost in 
the subsoil. Perhaps it would be more judicious to leave such 
soils to a state of nature, and expend our capital upon such as, 
containing the elements of fertility, only require mechanical aid 
to unlock their treasures, and gratefully afford an ample return 
for our investment. 
Calcareous Soils are those in which carbonate of lime predomi- 
nates, either in a fine state of division, as in chalk soils, or as 
calcareous gravel or even large irregular fragments. With few 
exceptions, all true calcareous soils are free from excess of 
moisture, light in colour, porous, and resting upon an open sub- 
soil, derived from disintegration of a hard rock or compact chalk ; 
often only a few inches in depth, they are liable to burn up in 
hot dry weather. Subsoil ploughing, by gradually deepening the 
surface, is very beneficial, and should not be neglected. Where 
a certain quantity of clay is present, the soil is termed a marl, 
and becomes of improved quality, capable of carrying heavy crops 
of wheat and beans. On the thinner lands, barley and root crops 
answer well, provided the surface is kept sufficiently firm by 
sheep treading and rolling. Limestone soils possess very little 
cohesive attraction, and though good absorbents, are bad retainers 
of water. As in the case of certain sandy soils, too frequent 
ploughing, especially for the root crop, is very injurious ; and I 
have seen an instance where the produce was reduced at least one- 
half from an extra ploughing. Calcareous soils, taken as a whole, 
are of a useful nature, adapted to a mixed husbandry, producing 
a sweet short grass suitable for sheep, and growing most crops, 
especially all those of a leguminous character. The root crop 
requires nice management, and is rather uncertain ; still with 
judicious treatment and the application of artificial manures it 
need seldom fail. The soils of the chalk formation, found prin- 
cipally in the South and Eastern counties of England, form 
perhaps the most considerable and collected examples of calca- 
reous nature. They are divided into two sorts, according as they 
are derived from the upper or lower beds : the former are usually 
poor, light, and full of flints ; the latter possess more tenacity, 
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