If you really care for the soil in your garden, you won’t want to
abandon it for the winter. One of the best things you can do for
it is to plant a winter cover crop in it.

Cover crops conserve nutrients, support a high biological
activity and produce a superior soil structure. When you plow
them into the soil, they’re sometimes called “green manures.”

Green manures offer succulent growth which decomposes easily in
the soil, releasing nutrients. While they’re smothering weeds,
they keep nutrients from leaching, too, and protect the soil over
the winter.

Cover Crops Improve Soil

Cover crops are any plant you sow into the garden that improves
the soil. The actual benefits depend on the plant type and how
much you grow.

Annual cover crops are usually grown as green manures. That is,
they are turned into the soil while still green, normally just
before they flower. Their greatest value is usually in the top
growth. But the roots are often beneficial, too.

Varieties of green manures are chosen for their fast, vigorous
growth and high production of green, succulent top growth.

The green matter decomposes quickly in the soil. When it does,
the result is a flush of biological activity and a quick release
of nutrients, some of which the roots may have accumulated from
the subsoil. The succulent residues replace some of the humus,
building a dynamic soil system.

The downside of growing a green manure is that it requires the
land be left idle for a time. That’s unpopular with many
gardeners.

However, crops other than legumes may be grown as “smother crops”
to control weeds. Commonly used as a winter cover and catch crop,
they protect the soil from erosion and conserve nutrients
otherwise lost.

Good Cover Choices

Traditional choices for green manures are buckwheat, small grains
such as rye and oats and annual grasses such as rye grass and
wheat.

Other crops are possible, however. Rapeseed, for instance, makes
a good green manure. But don’t follow it with another planting of
the cabbage family.

Sometimes legumes are grown. Austrian winter peas are commonly
planted in the fall for overwinter growth where winter
temperatures aren’t severe.

The green manure sod not only feeds soil organisms but protects
the soil from direct sun and rain.

Over the years, the combination of the high biological activity
and the extensive root system of grass leads to a superior soil
structure and a slow, but steady, increase in soil humus.

When a green manure sod is plowed under, a rapid breakdown occurs
with a sudden release of nutrients stored over a long time.
That’s why a cultivated crop following a green manure sod is
usually very successful.

To learn more about green manures and other cover crops, contact
the local county Extension Service office.