SOIL CONDITIONS. 25 
are those that are fine grained without much adhesive power, 
such as fine sand and some kinds of clays. When, however, 
such soils have a forest growth on them they are protected from 
washing by the forest floor, tree roots and the humus in the 
soil. Soil which contains large quantities of humus does not 
wash much, since the particles of organic matter bind it 
together; thus we find that newly-cleared timber land which 
contains large amounts of humus may not wash much for a 
number of years after the clearing, and then commence to wash 
very badly. The washing away then is due to the humus havy- 
ing become used up and there being nothing left to bind the soil 
particles together. In such cases the application of organic 
matter will help very materially. For this purpose manure, 
straw or other material may be applied, or crops like clover and 
the grasses, which leave considerable organic matter, may be 
grown on the land. Crops that leave very litthe humus in the 
ground, such as nursery stock, which is dug out by the roots, 
are most harmtul in exhausting the humus in the soil, and land 
used for this purpose needs heavy manuring with stable manure 
and an occasional seeding down to grass or clover. 
Alkali Soils. In the prairie portions and occasionally 
elsewhere in this section, we have a kind of soil in which there 
is a superabundance of carbonate and sulphate of soda. This 
kind of soil seldom extends over large areas and generally 
occurs in places lower than the surrounding land. In some 
places the alkali occurs in such abundance as to coat the surface 
of the soil with a white crust. On such land very few agricul- 
tural crops or trees grow well. The leaves of the trees growing 
there generally take on a yellowish color and the wood does 
not mature well in the autumn. Such land should be drained so 
that the surface water at least can run off. In this way the 
alkali can generally be washed out in a few years. It is seldom 
advisable to plant trees on these places, but if this seems desira- 
ble, as is sometimes the case on prairies, the best trees to plant 
are probably the Cottonwood and White Willow. 
