Sweet clover thrives on the adobe and granitic soils of the Pacific
coast; upon the gumbo, hardpan, prairie, and sandy soils of the western
North-Central States; and upon the heavy clay, loam, limestone,
and sandy soils of the South and East. In fact, it has been grown
successfully on all the principal soil types of the United States where
the soils were not acid and were well inoculated. It grows luxuriantly
on the Selma chalk (rotten-limestone) soils of Alabama and upon soils
rich in calcium carbonate in many parts of the country where the
lack of nitrogen and humus has caused large numbers of farms to be
abandoned. The plants thrive on newly exposed heavy clay soils and
upon steep embankments where little else will grow. Sweet clover is
more tolerant of poor drainage, overflow, and seepage conditions than
alfalfa. In irrigated sections, especially where the reservoir system
is in use, large bodies of land are likely to become useless for the
growth of alfalfa because of the rising of the water table. On such
areas sweet clover will make a vigorous growth. However, maximum growth
is to be expected only on well-drained soil.
Sweet clover will do well on many soils which are not fertile enough
to grow red clover or alfalfa, and it is on these soils that it will
prove most valuable. Like many other plants, it makes its best growth
on fertile soils rich in calcium carbonate, although it will make
sufficient growth on poor soils which are not acid to warrant planting
it on them. Many hilly pastures may profitably be seeded to sweet
clover. It will not only make a valuable addition to the forage of
these pastures but will improve the soil so that grasses will grow more
abundantly. Some of the best pastures in the Middle West are composed
of bluegrass, timothy, and sweet clover.