Vegetative Barriers to Prevent Soil Erosion and Increase Biological Pest Control in Agricultural Landscapes
Midland, Bay, and Tuscola Counties,
Michigan State University, Department of Entomology
Basin Program Funds:
Soil erosion and sedimentation from crop lands has been identified as a major
source of nonpoint source pollution in the Great Lakes basin. The U.S. Department
of Agriculture – Natural Resources Conservation Service (NRCS) identified
vegetative barriers as an effective measure for reducing sedimentation and
nonpoint source pollution. Recent Michigan State University, Department of
Entomology research has demonstrated that vegetative barriers also provide
habitat for weed seed and crop pest predators. The relative influence of this
benefit, however, has not yet been quantified.
In addition to creating a significant source of nonpoint source pollution,
agricultural land-use disturbs habitat, overwintering sites, refuge from pesticide
application and food resources for arthropods which prey on crop pests. The
lack of these habitats has been linked to increased crop losses which can,
in turn, lead to increased pesticide use and an attendant rise in nonpoint
source pollution. Including adequate habitat management in agricultural land-use
planning is the key to an ecosystem-based approach to managing these problems.
Properly managed vegetative barriers, such as cross wind trap strips within
fields and filter strips bordering fields, may serve multiple purposes including
wind and water erosion control and increased habitat for beneficial life forms.
In the Saginaw Bay region, high crop and tillage intensity
combined with inherent soil and landscape characteristics make soil erosion
and associated nutrient and pesticide loading in surface waters an acute problem.
Annual soil erosion into the Saginaw Bay watershed is estimated at nine million
tons. Under the Great Lakes Water Quality Agreement the watershed has been
designated an Area of Concern and become the focus of the U.S. Environmental
Protection Agency's first National Watershed Initiative Program. Under this
program, the NRCS is developing vegetative barriers as a component of a Conservation
Management System. These include technical guidelines for cross wind trap
strips to induce soil deposition and trap pollutants before they are deposited
downwind. At the same time the reduction in non-crop habitats, such as fence
and hedgerows, wood lots and riparian buffers has limited the abundance and
diversity of crop pest predators. One means of reintroducing the required
habitat into the landscape is through vegetative barriers. Michigan State
University research has developed natural enemy resource habitats comprised
of perennial grasses, legumes and flowering herbs most of which have also
been approved for use in vegetative barriers.
Three field test plots of varying composition, legume, switch grass and crops
(soybean in 1997 and corn in 1998), were established in Midland County, Bay
County and Tuscola County. At each site, researchers conducted bi-weekly pitfall
trapping for carabid ground beetles which are important insect and weed seed
predators. In addition, researchers conducted seed predation studies at the
Midland County site.
The research demonstrated that filter strips can contain a more diverse and
abundant carabid (ground beetle) community than the adjacent field. A total
of 36 species of carabids and 3360 individuals were found in the crop strip,
43 species and 4330 individuals in the legume plot and 50 species and 5247 individuals
in the switch grass test site with corresponding abundance following similar
trends. Carabids and other invertebrates were responsible for a significant
removal of weed seed. For instance, in one week they removed 84% of foxtail
seeds in the switch grass filter strip compared to 42% and 17%
in the legume and soybean filter strips respectively. An unexpected finding
was that crickets also consume large quantities of weed seeds.
The project team produced the following articles:
- Landis, Douglas and Lawrence Dyer, Conservation Buffers and Beneficial
Insects, Mites and Spiders, 1998, USDA--NRCS Conservation Information
Sheet. 4 pp.
- Menalled, Fabian and Landis, Carabid Beetles, Filter Strips and Biological
Control of Annual Weeds, Midwest Biological Control News 5 (December
1998): 4-5; www.wisc.edu/entomology/mbcn/weed512.html
- Landis, et.al., Habitat Management to Enhance Biological Control
in IPM, International Conference on Emerging Technologies in Integrated
Pest Management: Concepts, Research and Implementation. March 8-10, 1999
- Menalled, et.al., 2000. Ecology and Management of Weed Seed Predators
in Michigan Agroecosystems, MSU Extension Bulletin E 2716.
Additionally, project personnel hosted three field days which
attracted approximately 100 farmers, extension agents, and highschool students.
Midwest Biological Control News is received by all county extension offices
and extension entomologists in the 11 state north-central region meaning more
than 2,000 people saw the article. Another 2,000 people received the USDA NRCS
conservation information sheet as well.
Contact: Douglas Landis, (517) 353-1829