THE RANCH
VOL. XXX. No. 5.
COVER CROPS FOR NORTHWEST
The term "cover crop"is commonly
applied to a crop grown to prevent
injruy and losses to soils and also to
improve them either directly or in
directly. It may be used as a soiling
crop or as a green manure orop. It
may be grown either in summer or
winter, whenever the land is idle or
not producing a regular crop. In
western Washington where rainfall is
heavy, it is especially desirable that
the land be covered during the long,
rainy season.
USES OF COVEK CROPS
Cover crops are used (1) to prevent
the soluble plant foods which have
accumulated during the late summer
and early fall from being leached out
and carried away by winter rains; (2)
to prevent the surface erosion of hill
sides or slopes by winter rains; and
(3) to supply humus.
Plant food is elaborated most rapid
ly in warm, well tilled, well drained
soils. These conditions are likely to
obtain in late summer after such
crops as wheat and oats and all or
dinary farm crops have ceased to draw
on the available supply. Cover crops,
sown in late summer or early fall, or
as soon after the regular crop is re
moved as the moisture contents of
the soil will insure germination and
growth, use this plant food and store
it up on their roots and tops and in
case of the roots, and also the tops
if turned under as green manure, re
turn it for the next crop. This is
especially true and important in the
case of nitrates, whicb are most ex
pensive and most easily washed away.
The network of fibrous roots as well
as the above-ground stems of the
cover crop,, protect the soil from the
erosive action of heavy rains. The
excess of water is stored up and com
pelled to run off slowly and in sheets,
rather than rapidly and in channels,
thus carrying away the finest and
most fertile part of the soil. The
humus which is added to the soil by
these cover crops renders the soil
KENT and SEATTLE, WASH, SEPTEMBER i, 191 1. SOC5 OC Per Year > 5c the Copy
BY L. J. CHAPIN
AGRONOMIST WESTERN WASH. EXP. STA.
more sponge like and thus a greater
amount of water is absorbed and
stored up for use.
The effect of the cover crop on the
soil will depend to some degree, on
the root habit of the crop. The
legumes are deep rooted plants and
are prized for this reason as well as
for other merits. Their roots open up
storage channels to a considerable
depth and so lessen the amount of
the run off.
Under the ordinary system of crop
ping in which the crop is not fed to
live stock on the farm and the manure
WESTERN WASHINGTON HAY FIKLU.
carefully preserved and returned to
the soil, the cover crop affords the
only method of supplying the humus
necessary to soil fertility. In such
cases it is well to turn under the
entire crop in the spring as a green
manure crop. The bacterial action
in the soil is dependent on its humus
—Courtesy Hociuiam Sawyer.
STRAWBERRY GROWING IN WESTERN WASHINGTON.
content, the humus serving as food
for the bacteria. So in order that
the soil may contain the necessary
elements for plant growth, the humus
content of the soil must be maintain
cd.
Humus looseus a heavy clay soil
and this drains and warms it. The
better circulation of air, together
with the increased temperature in
duces a more rapid bacterial action
and thus promotes the growth of
plants. The difference in temperature
between a heavy, poorly drained soil
and the same soil well drained and
well supplied with humus often
amounts to the normal change of
temperature of one month in spring.
This means that a soil properly tilled
will mature its crop a month earlier
than a poorly tilled one and thus miss
the drier portion of the summer.
It' a soil is too open, however, as is
often the case in a sandy soil, too
tree a circulation of air obtains and
nitrification goes on too rapidly. The
humus is soon all oxidized and the
soil becomes dry and overheated. It
is therefore very essential that the
supply of humus be maintained in v
sandy soil. This, humus, by tilling
the pores 01 spaces between the sand
particles and by serving as an absorb
ent, thus retaining moisture, prevents
the too rapid circulation of air and
maintains a more uniform tempera
ture.
METHOD OF HANDLING
A word with reference to the method
of handling a cover crop may be iv
order. It should be sown as soon
after the regular crop is removed as
it will germinate. This is important
in order that the growth may be as
large as possible to cover the soil dur-
(Continued on page 11.)