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cautions that the soil must be left unplowed Suppress weeds: Cover crops use
to retain the carbon. Biomass also could be water and nutrients and block light that
lost through haying and grazing, he says. is needed by weeds. Cover crops also
Carbon sequestration rates depend on change the soil surface temperature or
temperature, latitude, soil texture and other possess herbicidal compounds in their
environmental and management factors. roots that can effectively prevent weeds.
Cereal rye, barley, oats and mixtures can
Reduced fertilizer costs: Cover crops be effective for keeping weeds at bay,
such as hairy vetch, medium red clover, SARE says.
Austrian winter peas and fibrous-rooted
cereal grains can contribute nitrogen to the Improve soil health and nutrient
following cash crops. Reducing nitrogen cycling: According to SARE, there are
usage, in turn, can reduce emissions of several ways that cover crops can improve
soil health. For example, rye
can add organic matter to
the soil, sorghum sudangrass
has deep roots that can help
relieve soil compaction and
ryegrass can “stabilize field
roads, inter-row areas and
borders when soil is wet.”
Conserve soil mois-
ture: Cover crops can help
increase water infiltration
and reduce evaporation.
Rye, wheat and sorghum-su-
dangrass hybrids can effec-
tively cover the soil surface,
while legumes like medic
and Indianhead lentils may
conserve more moisture
than conventional bare fal-
low in dryland areas.
Protect water quality:
nitrous oxide from fields, the largest source Cover crops can reduce pollution from
of greenhouse gas emissions from U.S. sediments, nutrients and chemicals by
agriculture. taking up excess soil nitrogen, reducing
erosion and slowing runoff. Authors of the
Reduce soil erosion: With enough stalk SARE report cite a study conducted on
and leaf growth, many cover crops can Georgia corn fields that found a rye cover
help prevent soil loss, particularly in winter crop “scavenged” from 25% to 100% of
months when nothing else will grow in fields. residual nitrogen.
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