in forest areas west from Lake Superior, and also in
other parts, the sandy soils of which sustain a growth of Jack Pine
(_Pinus murrayana_) trees, do not grow white clover with much vigor.
The prairie areas of Canada, westward from Lake Superior to the
mountains, do not grow white clover with much success, and the
adaptation for its growth would seem to lessen gradually until the Rocky
Mountains are approached.

=Soils.=--Small white clover will grow on almost any kind of soil, but
by no means equally well. Highest, probably, in adaptation, especially
when climatic conditions are considered along with those of soil, are
the clay loams west of the Cascade Mountains and northward from
California to Alaska. During the moist months of early summer, this
plant turns the pastures in these areas into a flower garden. Almost
equally high in adaptation are the volcanic ash soils of the Rocky
Mountain valleys. When amply supplied with water, the finest crops of
white clover can be grown even superior to those grown on the lands
described above. Almost the same may be said of what are termed the
hardwood timber soils, which are usually made up of clay loam lying upon
clay. Such areas abound in Minnesota, Wisconsin, Michigan, Ontario and
some States further south. In these soils it grows with much luxuriance,
more especially when lime and potash are abundant. Similar luxuriance
may be looked for in the deposit soils of river basins in which the clay
element predominates, but not in those that are largely made up of sand.
It will also grow well on the stiffest clays, whether white or red, when
moisture is present. On prairie soils, the success attending it is
dependent largely on their texture, composition and the moisture which
they contain under normal conditions. The more firm these soils are,
the better will the clover grow in them, and _vice versa_. This is
equivalent to saying that the more clay they contain, the better will
the white clover grow in them.

Where the humus soils of the prairies are deep and are underlaid with
clay, white clover will grow much better in the subsoil, if laid bare,
than in the surface soil. Prairie soils which lift with the wind are ill
adapted to the growth of this plant, whatsoever may be their
composition. Much of the soil in the semi-arid belt would grow this
plant in fine form, but want of moisture, where irrigation is absent
makes its growth prohibitory in a large portion of this area. On