and then harrowing it. Inoculations thus tried under the
supervision of the United States Department of Agriculture have proved
quite successful.

Where any legume is extensively grown surrounding soils come to be
inoculated through the agency of winds and water. The increase brought
to the yield of plants on various soils runs all the way from a slight
gain to 1000-fold. And when soil is once inoculated it remains so for a
long time, even though the proper legume should not be grown again on
the same soil.

The amount of nitrogen that may thus be brought to many soils by growing
clover and other legumes upon them is only hedged in practically by the
nature of the rotation fixed upon. An acre of clover when matured will
sometimes add 200 to 300 pounds of nitrogen to the soil under favorable
conditions. Where the soil contains the requisite bacteria, the young
plants begin to form tubercles when but a few weeks old, and continue to
do so while the plant is active until mature. That the plants use much
of the nitrogen while growing would seem to be clear, from the fact that
toward the close of the growing season the tubercles become more or less
broken down and shrunken.

CHAPTER III

MEDIUM RED CLOVER

Medium Red Clover (_Trifolium pratense_) is also known by the names
Common Red Clover, Broad-Leaved Clover and Meadow Trefoil. The term
medium has doubtless come to be applied to it because the plants are in
size intermediate between the Mammoth variety (_Trifolium magnum_) and
the smaller varieties, as the Alsike (_Trifolium hybridum_) and the
small white (_Trifolium repens_). But by no designation is it so
frequently referred to as that of Red Clover.

This plant is spreading and upright in its habit of growth. Several
branches rise up from the crown of each plant, and these in turn
frequently become branched more or less in their upward growth. The
heads which produce the flowers are nearly globular in shape, inclining
to ovate, and average about one inch in diameter. Each plant contains
several heads, and frequently a large number when the growth is not too
crowded. When in full flower these are of a beautiful purple crimson,
hence, a field of luxuriant red clover is beautiful to look upon. The
stems of the plants are slightly hairy, and ordinarily they stand at
least fairly erect and reach the height of about one foot or more; but
when the growth is rank, they will grow much higher, even as high as 4