ay, and with a view to retain moisture. It is at least
questionable, however, if disking so frequently would not soon tend to
thin the plants too much, to say nothing of the labor while the work is
being done.

The idea of stirring the surface soil in alfalfa fields is by no means
new. In England the plan prevailed to some extent years ago of harrowing
the fields in the autumn with heavy harrows until, when the process was
completed, they would take on the appearance of the bare fallow for a
time. In the Eastern States and in some parts of Canada the harrow is
used instead of the disk, but usually the latter will do the work more
effectively and with less cost. Frequently, when the disk has been used
on alfalfa, it may also be advantageous to run a light harrow over the
ground to smoothen the surface.

With a view to renovate the crop and increase the yields, in some
sections, as in the Atlantic States, it has been recommended to
top-dress alfalfa fields with farmyard manure every autumn. This, no
doubt, would prove very effective, but it would also be very expensive,
unless in the neighborhood of large cities. It would be impracticable
without neglecting the needs of the other crops of the farm. In the
mountain areas of the West, it has been found that the cost of
fertilizing with farmyard manure is in the meantime greater than the
increased production in the alfalfa is worth, but it may not be always
thus, even on these rich lands. Some Eastern growers also apply more or
less gypsum. This is generally sown over the fields after the crop has
begun to grow in the spring.

Renovating alfalfa fields is much more easily and effectively done, as
would naturally be expected, in areas where conditions are highly
favorable to its growth than where these are only moderately favorable.
In some of the mountain valleys instances have occurred in which alfalfa
fields have been plowed and sown with oats, with a result, first that a
good crop of oats was reaped, and second, that fairly good crops of
alfalfa were harvested the following season without re-sowing the field.

=Sources of Injury to Alfalfa.=--Chief among the sources of injury to
alfalfa, after the plants have become established, are frost in
saturated ground, ice, floods, grasshoppers, gophers, dodder, and
pasturing by live stock in the late autumn or winter. When it happens
that two or three of these act in conjunction, the injury following is
just so much more rapid