286 Sustainable Farming
3 common ways to use green manures
• Grow them together with main crops such as maize, millet, and cassava.
• Plant them when the land is going to be left to rest (fallow). A 1-year
fallow with green manure will improve soil and kill weeds just as well as
a 5-year fallow with no green manure.
• Grow them during the dry season, after the main crop is harvested.
The best cover crop is a mix of plants. A grain that grows fast and tall will add
organic matter to the soil, while a bean crop will add nitrogen and will cover
the ground. Talk to other farmers in your region to learn what works best on
your soils.
Grow the crop until
harvest. Use the beans
or grain for food or
fodder, and then cut
down the stalks.
Clear spaces in
the cover crop
and plant your
next crop right
into the ground.
Mulch
It is best to keep soil covered, even during the growing season. Mulch is
anything used to cover the soil. Mulch helps hold water, control weeds, and
prevent erosion. Plant wastes, such as maize stalks, bean vines, or grasses
make the best mulch, because they can be simply left to rot in the field, and
they add organic matter to the soil. Weeds can be used in the same way, but
they must be cut before they make seed to prevent them from growing back.
Mulch should not be more than 10 cm thick. A very thick mulch can hold
too much moisture and cause plant diseases.
Do not let
mulch touch
the stems of
plants. It can
cause plants
to rot.
Straw and grass cuttings make good
mulch because they break down slowly.
A Community Guide to Environmental Health 2012