cereals, corn, the sorghums, the millets
and cotton. But since these clover plants have the power to bring
nitrogen from the air, it must not be supposed that they will grow with
sufficient vigor in soils destitute of this element. They must be able
to appropriate enough from the seed soil to give them a good start
before they can draw nitrogen from the air, hence, though they may be
made to follow almost any kind of crop, it may sometimes be necessary to
apply some nitrogenous fertilizer before they will make a vigorous
growth.

The clovers, unless in the case of some of the smaller varieties, are
more commonly sown to provide hay than pasture in the first crops
obtained from them. The value of the hay is increased or lessened in
proportion as weeds are present. To insure cleanliness in the hay crop,
therefore, the system which aims to sow clover seed on land to which
clean cultivation has been given while growing on them a cultivated
crop, as corn or field roots, meets with much favor. The mechanical
condition of the soil immediately after growing these crops also favors
the vigorous growth of the young clover plants, more especially when
they are sown upon the surface of the land after some form of surface
cultivation, rather than upon a surface made by plowing the land after
cultivation has been given to it, but to this there may be some
exceptions.

Clover in some of its varieties is frequently grown from year to year in
orchards and for the two-fold purpose of gathering food for the trees
and providing for them a cover crop in winter. The medium red and
crimson varieties are preferred for such a use. The latter is the more
suitable of the two, since it does not draw on soil moisture needed by
the trees, owing to the season at which it is grown. Enough of the seed
of these crops may be allowed to mature to re-seed the land from year to
year, and thus keep it producing. The clover plants not only gather
nitrogen for the fruit trees, but in their decay they increase the power
of the soil to retain moisture for the benefit of the trees.

Some varieties of clover may be grown as catch crops, that is, as crops
which are grown in addition to some other crop produced the same season.
When thus grown, it is usually for purposes of soil improvement rather
than to furnish food. The varieties best adapted for this purpose in the
Northern States and Canada are the medium red and the crimson, the
latter being much more circu