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 hav- 

 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 little humus in the 

 ground, such as nursery stock, which is dug out by the roots, 

 are most harmful 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. 



