hich should rather be used to preserve and sustain
life than to destroy it. The waste of nitrogen through the loss of
sewerage is enormous, nor does there seem to be any practicable way of
saving the bulk of it.

In many soils the germs which produce nodules are present when clovers
are first grown on them. But where they are not present, the clover
plants have no more power to gather nitrogen than wheat or other
non-leguminous crops. But since in other soils they are almost entirely
absent, how shall they be introduced? The process of introducing them is
generally referred to as a process of inoculation, and soils when
treated successfully are said to be inoculated.

Three methods have been adopted. By the first, as previously indicated,
the grower perseveres in sowing clover at short intervals in the
rotation. He may also add farmyard manure occasionally, and thus,
through the inherent power of multiplication in the bacteria, they
increase sufficiently to enable the land to grow good crops. By the
second method, inoculating is effected through soil which is possessed
of the requisite bacteria; and by the third, it is effected through the
aid of a prepared product named nitragin.

When fields are to be inoculated by using soil it is obtained from areas
which have grown clovers successfully quite recently, and which are,
therefore, likely to be well filled with the desired bacteria. In some
instances the seed is mixed with the soil and these are sown together.
To thus mix the seed with the soil and then sow both together broadcast
or with a seed drill is usually effective, and it is practicable when
minimum quantities of soil well laden with germs are used. In other
instances the soil containing germs is scattered broadcast before or
soon after the seed is sown. Considerable quantities of earth must needs
be applied by this method.

It should be remembered that each class of legumes has its own proper
bacteria. Because of this, inoculation can only, or at least chiefly, be
effected through the use of soils on which that particular class of
legumes have grown, or which are possessed of bacteria proper to that
particular species. In other words, bacteria necessary to the growth of
vetches will not answer for the growth of clovers, and _vice versa_. Nor
will the bacteria requisite to grow medium red clover answer for growing
alfalfa. In other words, the bacteria proper to the growth of one member
of even a family of pl