AGRICULTURE. 
373 
He who possesses on his estate the three earths, 
clay, sand, and lime of a good quality, with facili- 
ties for drainage or irrigation, has all the materials 
for permanent improvement ; the grand desiderata 
Ml agriculture being to render wet lands dry, to sup- 
ply dry lands with sufficient moisture, to make ad- 
hesive soils loose, and loose soils sufficiently ad- 
hesive. The intermixture of soils, where one kind 
of earth is either redundant or deficient, is practised 
in some countries with great advantage. Part of 
Lancashire is situated on the red sandstone. This 
rock, being principally composed of silicious earth 
and the oxide of iron, forms of itself very unpro- 
ductive land ; but, fortunately, in many situations it 
contains detached beds of calcareous marl near the 
surface. By an intermixture o/ this marl with the 
soil, it is converted into fertile land, and the neces- 
sity for manure is superseded. The effect of a 
good marl applied liberally to this land, lasts for 
more than 20 years. In some lands a mixture of 
light marl, which contains scarcely a trace of cal- 
careous earths, is found of great service. The 
good effect of this appears to depend on its giving 
to the sandy soil a sufficient degree of tenacity. 
The steril and gravelly soils in Wiltshire have 
been recently rendered productive by mixing them 
with chalk ; the most liberal application of manure 
having been found ineffective or injurious. In stiff 
clay soils, where lime is at a great distance, the 
land might frequently be improved by an intermix- 
ture with silicious sand. A proper knowledge of 
the quality of the subsoil, and the position of the 
sub-strata, is necessary to ascertain the capability 
of improvement which land may possess. It may 
frequently happen, that a valuable stratum of marl 
or stone, which lies at a great depth in one situa- 
tion, may rise near the surface in an adjoining part 
of the estate, and might be procured with little ex- 
pense. When earths are properly intermixed, in- 
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