4 
Garden Work 
the rivers, and the silt is deposited as before described. 
We need not wonder now why alluvial soil is such a very 
fertile soil when we remember that there is so much 
available plant food in it and such a varied assortment 
of soil particles. 
B. LOAM SOILS 
These come next in order of fertility, but they are 
more important than the alluvial. Whereas the latter 
are only formed in certain places by the action of rivers, 
loam soils are fairly general. They may be divided into 
three classes: loams, clayey loams, and sandy loams. 
A clayey loam may contain from 50 to 60 per cent 
of clay, while a sandy loam contains not more than 
30 per cent. A loam, however, may contain from 40 to 
50 per cent. These have about equal proportions of 
very small particles which cling together very closely 
and are held in a compact mass by a sticky substance 
called silicate of alumina, and also of coarser and more 
porous materials. Now the advantages of a loam soil 
are obvious. First, it retains sufficient moisture for the 
use of the plants — except in periods of continued drought 
— through the retentive nature of the finer materials, and 
yet, through the liberal mixture of the coarser material, 
it does not hold too much moisture so as to render the 
roots of plants cold during the spring. The air also is 
able to have free access to the roots, a most necessary 
condition for the health of the plant. 
A loamy soil is also easy to cultivate, being neither 
too stiff nor yet too friable. 
