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![NRCS This Week mast head](https://webarchive.library.unt.edu/eot2008/20090117125819im_/http://www.nrcs.usda.gov/news/thisweek/images/mastheaddshadow3.jpg)
Conservation Reserve Enhancement Program (CREP) Maryland Style
![an experimental soybean plot designed to simulate insect populations in fields buffered by different flower species or combinations of species](https://webarchive.library.unt.edu/eot2008/20090117125819im_/http://www.nrcs.usda.gov/news/thisweek/images/buffer2med.jpg)
an experimental soybean plot designed to simulate insect populations in
fields buffered by different flower species or combinations of species
(click to enlarge) |
Considering that erosion-prone areas are less productive for farming, and
Maryland’s Conservation Reserve Enhancement Program (CREP) assists landowners
who want to protect the Chesapeake Bay watershed, installation of buffers should
be a win-win situation. Yet, Galen Dively, Cooperative State Research,
Education, and Extension Service specialist and entomologist
at the University of Maryland, and his co-researchers are discovering that
designing the perfect riparian grass buffer is much more complex than previously
thought.
Funded by a USDA-Sustainable Agriculture Research and Education (SARE) grant,
Dively set out to build a grass buffer that would simultaneously attract the
fewest pests and the most natural enemies. Along with a team of graduate
students and other researchers, Dively is investigating different species of
forbs and grasses and plans to publish a series of recommendations for the
ideal buffer — one that will harbor a vast array of wildlife and beneficial
insects while still improving water quality.
Through his research, Dively has found that many commonly held assumptions about
buffers in the Chesapeake Bay region may not be true. For example, while Dively
first believed that warm-season grasses would promote greater insect diversity
since they are native, structurally diverse, and able to weather Maryland’s
scorching summers, his findings showed the opposite.
“Research indicates that insect diversity is often greater in non-native,
cool-season grasses,” says Dively, who has been studying buffers on twenty farms
within Maryland’s Eastern Shore. “These grasses have been bred for many years
and have lost a lot of their natural defenses against herbivorous insects.” Thus, they may serve as reservoirs for some harmful insects yet simultaneously
enhance populations of beneficial insects that could migrate into the field to
feed. Dively’s work is providing insights into the pest management consequences
of these two conflicting effects.
Warm-season grasses still have their benefits though — they harbor fewer aphids
and other cold-adapted pests than cool-season grasses. In late summer, insect
diversity evens out between the two types of grasses as hot, dry conditions
stress cool-season grasses, causing insects and mites to disperse.
Careful management of cool-season grasses in buffers is key. “Cool-season
grasses get an undeserved bad reputation in terms of pest control because of the
way they are managed,” Dively says. Under CREP contracts, landowners are not
allowed to mow from April 15, through August 15, to protect nesting birds. Many
farmers mow their cool-season grass buffers in late August, which could
inadvertently force pests to move onto crops.
Meanwhile, the work of graduate student Peter Blank — whose research is funded by
the NRCS Agricultural Wildlife Conservation Center through the Chesapeake
Watershed Cooperative Ecosystem Studies Unit — is also challenging conventional
wisdom on buffers. While most birds were thought to prefer native, warm-season
grasses over introduced plant species, Blank’s work suggests that during the
breeding season, most birds prefer to nest in a vegetative structure that is
vertically dense and provides good cover, rather than favoring a particular
grass type.
Blank also found that in the winter, cool-season grass buffers had lower bird
species density and richness than warm-season buffers, largely due to late
summer mowing, which leaves the buffer short and exposed throughout the winter.
He recommends mowing in March or April, just before breeding season, as fall
mowing may reduce cover from predators and availability of food.
Finally, Dively supports more incentives for landowners to plant flowering
perennials in buffers. Although more expensive, flowers produce pollen and
nectar which attract beneficial insects. Even planting flowers, however, must be
done with great care.
“At first we thought that the more attractive a flower is to insects, the better
that flower is suited to planting in buffers,” he says. However, too many
flowers or the wrong types may draw beneficial insects away from the crop
fields. Case in point is the partridge pea; when abundantly growing along the
edge of a field, it can be too effective, acting more as a beneficial insect
sink rather than a source.”
About SARE
Since 1988, SARE has helped advance farming
systems that are profitable, environmentally sound and good for communities
through a nationwide grants program. The program, administered by
CSREES and
USDA, funds projects and
conducts outreach designed to improve agricultural systems and natural
resources.
NRCS field office professionals frequently collaborate on SARE-funded projects
and are valuable partners to the SARE program. NRCS staff serve on SARE’s
national Operations Committee, on regional Administrative Councils, on State
committees and are actively engaged as technical advisers and collaborators on
SARE-funded research grants around the U.S.
For more information, visit
the SARE website or for more information about the regional SARE programs, click on the region
area of the map below.
Your contact is Diana Friedman, SARE
research associate, at 301-504-6422.
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