Leopold Center for Sustainable Agriculture

Agroecology work fuels landscape change; current interest turns to biomass

Back to Leopold Letter Spring 2007

By ANNE LARSON, Special to the Leopold Center

Nature’s lessons is “everything in its own time.” Among the most successful efforts supported by the Leopold Center in its first 20 years are conservation practices that prove the wisdom of that lesson.

The nationally-touted Bear Creek riparian (streamside) buffers are now the object of research on the timely issue of biomass production, fueling even greater interest in the soil-saving, nutrient-trapping buffers.

The project grew from researchers’ recognition of the need to reduce nonpoint source (NPS) pollution, while adding woody biomass to the farmer’s suite of cash crops. Funded by the Leopold Center from 1990 to 2002, the project continues to research soil, water quality, nutrient management, watershed improvement and wildlife habitat implications of the buffers.

The Leopold Center’s interdisciplinary Agroecology Research Team studied the economic, agronomic, biological and sociological impacts of conservation practices. The significant NPS pollution reduction that resulted from buffers quickly became apparent, and garnered recognition from regional and national conservation and environmental organizations.

On the other hand, Dick Schultz, professor and researcher in the Iowa State University Department of Natural Resource Ecology and Management (NREM), says that when the project began, analyses showed that markets for biomass just weren’t there.

Now, 17 years later, the silver maple, green ash, willow and poplar planted on the Bear Creek buffer strips have matured and can offer another avenue for research on the economic viability of generating income from biomass. As Schultz and his colleagues continue their efforts, they will be quantifying the potential of buffers for carbon sequestration and use in the burgeoning bio-energy field.

Such intense interest in bioeconomy opportunities may cause some acres to come out of Conservation Reserve Program (CRP) set-aside. “If more land is used for corn after corn for ethanol production,” Schultz says, “the existence of streamside buffers will become even more important.” So not only will the riparian filters potentially be part of the energy generation mix, they also may help ameliorate increased nonpoint source pollution.

Where the effort began
The Agroecology team concept was approved by the Leopold Center’s Advisory Board in 1988, and the team began work in 1990. The group, led by Schultz and Professor Emeritus Bruce Menzel, set out three goals:

  • To assess the impact of agriculture on the structure and function of regional agroecosystems,
  • To design and test small-scale agricultural landscape management systems that could reduce the negative impacts and improve natural ecosystems, and
  • To develop a holistic approach for management of regional agroecosystems that were environmentally sound, socially acceptable, and economically feasible.

Two watersheds were part of the early work: Storm Lake in Buena Vista County and Bear Creek in Story County. Work included using geographic information systems for assessing the landscape, monitoring water quality, surveying farmers and residents for socioeconomic information, and designing and testing buffer strips.

At the time, the buffer system installed on Ron Risdal’s farm was one of the few such restorations in the United States. The buffer design consisted of five rows of trees, two rows of shrubs, and a 24-foot swath of switchgrass. The idea was that fast-growing tree species could be harvested for biomass in short rotations of ten to 20 years, depending on the species. These species, which can resprout from the trunk, can be harvested three to four times before productivity decreases. The harvesting of the aboveground biomass also serves to remove the chemicals that are stored in the plants. The buffer design includes a small constructed wetland that intercepts and filters pollutants and examples of streambank bioengineering that stabilize eroding banks.

Telling the successes

In 1998, the Bear Creek riparian management project became one of 12 National Agricultural Restoration Demonstration sites identified by the U.S. Department of Agriculture. Countless tours have been conducted at Bear Creek by leaders of more than 50 conservation and farm organizations in Iowa and 30 countries abroad.

Since the inception of the Bear Creek project, more than 64,000 acres bordering Iowa streams have been protected by buffers. Iowa ranks third among all states in use of the riparian buffers, and accounts for 8 percent of all the acres currently classified by USDA as protecting streams. Many of those buffers are funded from the continuous CRP signup program. In the Bear Creek area alone, more than 15 landowners have installed woody and grass buffers since the pioneering efforts on Risdal’s farm.

Drawing on the early successes of Bear Creek, the Iowa Buffer Initiative was formed to encourage increased use of the practice along Iowa streams. The program, credited with spurring CRP sign-up by nearly 28 percent, was led by Iowa-based Trees Forever and sponsored by Novartis Crop Protection, the Iowa Farm Bureau Federation, Iowa Department of Natural Resources, the Environmental Protection Agency, Natural Resources Conservation Service, the ISU NREM department and the Leopold Center.

Research indicates that soil organic matter carbon and soil infiltration rates can increase in a relatively short time after the establishment of perennial vegetation in a multispecies riparian buffer. These changes should increase the ability of the buffer’s soil to process non-point source pollutants. Data also have shown that buffers can cut sediment in surface runoff by 90 percent, cut nitrogen and phosphorus in runoff by 80 percent and remove up to 90 percent of groundwater nitrate. Importantly, streambank stability is greatly improved by the practice.

In a song bird survey in the Bear Creek Watershed, narrow cool-season grass and weed strips typically left along unbuffered streams contained nine common species while a ten-year-old riparian forest buffer contained 43 species. Game species such as pheasants are present in large numbers making the buffers prime hunting areas. Aquatic life also has flourished in the protected streams.

CRP payments, wildlife enhancement and water quality improvement might be reasons enough for landowners to install the buffers. Now that the bio-fuels industry is on the verge of blossoming in Iowa, adding biomass crops to the farmer’s palette seems destined to seal the deal.

Accomplishments and project awards

  • 2005 White House Conference on Cooperative Conservation – Agroecology Issue Team of Iowa State University was recognized for outstanding leadership and personal stewardship in achieving results thorough cooperative conservation.
  • Trees Forever, President’s Award, 2004 – The award is presented annually to a small group of recipients that have played a special role on behalf of Trees Forever. Iowa State was cited for research at the National Bear Creek Research and Demonstration site, partnership on an outreach to landowners on water quality initiatives, research on urban forestry and collaboration on low impact development in forested areas.
  • Soil Conservation Award, 2000 – Iowa Department of Agriculture and Land Stewardship – Division of Soil Conservation and the Iowa State Soil Conservation Committee.
  • National Restoration Demonstration Watershed, 1999 – Clean Water Action Plan (United States Environmental Protection Agency), for showcasing the application of stream corridor restoration technology and for improving the community, the environment, and water quality in support of the Clean Water Action Plan.
  • National Riparian Buffer Research and Demonstration Area, 1998, United States Department of Agriculture – In recognition of the Agroecology Issue Team, landowners Ron and Sandy Risdal and Lon and Sandy Strum, and the many other landowners, agencies, organizations, and institutions involved in the project.
  • Ada Hayden Conservation Education Award, 1998, Iowa Association of Naturalists and the Iowa Conservation Education Council – For outstanding efforts in education of conservation professionals and private landowners about preservation, land management, and natural resource conservation.
  • Journal of Soil and Water Conservation Best Research Award, 2003 – For paper published: Lee, Kye-Han, T.M. Isenhart, and R.C. Schultz. 2003. Sediment and nutrient removal in an established multi-species riparian buffer. Journal of Soil and Water Conservation 58(1):1-8.

Back to Leopold Letter Spring 2007