32 MANURING THE SOIL. [chap. ii. 
sand. A poor sandy soil is necessarily a 
nearly barren one ; because it will not retain 
either water, or the nutritious juices from ma¬ 
nure, long enough to afford nourishment to 
the plants grown upon it; and it is obvious 
that a soil of this kind can only be rendered 
fertile by mixing it with clay; which would 
change it into a sandy loam. 
A stiff clay is unfertile from its attract¬ 
ing moisture and retaining it round the roots 
of the plants till they become swollen and 
unhealthy. It also retards the decomposi¬ 
tion of manure, and obstructs the progress of 
the roots, which waste their strength in the ef¬ 
forts they make to penetrate, or twine round, 
its adhesive clods. Soils of this description 
are improved by a mixture of sand, gravel, 
road grit, or any substance which tends to 
separate the particles of the clay, and to ren¬ 
der it light and friable. 
Chalky soils succeed better unmixed, than 
any of the other kinds; but chalk being 
a carbonate of lime, can hardly be called a 
primitive soil. The chalk, however, from its 
whiteness is colder than any other soil; as 
it does not absorb, but reflects back the rays 
