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An integrated riparian management system was developed along a central Iowa stream to demonstrate the benefits of properly functioning riparian zones in the heavily row-cropped Midwestern United States. The system consists of three components; a multi-species riparian buffer strip, soil bioengineering technologies for streambank stabilization, and a constructed wetland to intercept and process non point-source pollutants in agricultural drainage tile water.
The general multi-species riparian buffer strip layout consists of three zones. Starting at the stream bank edge, the first zone includes a 9 m (30 ft) wide strip of 4-5 rows of trees, the second zone is a 4 m (13 ft) wide strip of 1-2 rows of shrubs, and the third zone is a 7 m (22 ft) wide strip of native warm-season grass. This design is important because the trees and shrubs provide perennial root systems and long-term nutrient storage close to the stream while the grass provides the high density of stems needed to dissipate the energy of surface runoff from the adjacent cropland.
Water and chemical movement across the buffer strip are being monitored using a combination of piezometers, tensiometers, and tension lysimeters. Initial results show that nutrient and pesticide concentrations in the unsaturated zone are much lower across the buffer strip than within the adjacent cultivated field. After six years, soil water in the unsaturated zone under the buffer strip never exceeded 3 ppm of NO3–N, or 1 ppb of atrazine, even though concentrations as high as 30 ppm and 8 ppb, respectively, are measured in the cropfield. However, nitrate concentrations in the shallow groundwater are highly variable between adjacent transects, suggesting that nitrate contained within shallow groundwater may be moving preferentially across the buffer strip. We are expanding our efforts to accurately characterize groundwater and chemical movement across the buffer strip.
Several streambank bioengineering technologies are being demonstrated at the project site. The first is a combination of live willow posts and dead, bundled, hardwood revetments. The other is a combination of live willow posts and geotextiles in combination with Eastern red cedar or rock rip-rap for protection of the streambank toe. These installations have been very effective in stabilizing the banks.
A small wetland was constructed to intercept and process agricultural chemicals contained in tile drainage. Nitrate loss rates per square meter of wetland sediment are comparable to those observed in experimental wetlands and are dependent upon temperature and residence time of the pollutant laden water. It is expected that the nitrate removal capacity of the wetland will increase as the wetland matures and accumulates a layer of dead plant material.
Establishment of the riparian management system has dramatically improved the wildlife habitat on the farm. Results demonstrate that nearly four times as many bird species are using the buffer strip than are using an adjacent, non-buffered stream reach.
Technology transfer efforts have been very successful. In the last two years over 30 formal tours (>1,000 persons) have visited the site. A self-guided trail has been established to provide information to visitors to the site. Thirteen papers have been prepared and 53 invited presentations have been made to local, regional and national groups. An extension bulletin series entitled “Stewards of Our Streams” is also being produced.
The overall objective of this research has been to develop a riparian management system (RiMS) to rehabilitate riparian zones in agricultural ecosystems and to transfer this information to landowners, resource agency personnel, and policy-makers. The integrated management system is intended to restore ecosystem functions associated with a healthy and diverse riparian zone. The system model includes the establishment of a multi-species riparian buffer strip (MRBS) of native tree, shrub, and grass vegetation to control the adverse effects of upland agriculture on stream water quality and to improve wildlife habitat. The initial MRBS was established in 1990 on the Ronald Risdal farm along Bear Creek in central Iowa. The ACE project has provided for the continued development of this site and has allowed for some of the initial quantification of the effects of a MRBS on surface and groundwater quality. In addition, the ACE project has provided for the demonstration of two other components of the RiMS model: soil bioengineering technologies to reduce streambank erosion and constructed wetlands to intercept and process nonpoint source pollution contained in agricultural tile drainage. The result is a unique riparian management system having three separate practices located on the Risdal farm. Other objectives of this project have been to evaluate the effects of the riparian management system on wildlife populations and to evaluate the costs of establishing and maintaining the three components of the RiMS. Finally, the ACE project has provided for extensive technology transfer efforts. The research is being conducted by the Iowa State Agroforestry Research Team and the Agroecology Issue Team of the Leopold Center for Sustainable Agriculture.
Specific objectives of the project are as follows:
Objective 1 – Demonstrate and quantify the ability of the MRBS to filter, transform, and act as a sink for nonpoint source pollutants.
Objective 2 – Develop a small wetland to intercept and process field tile drainage.
Objective 3 – Demonstrate the ability of soil bioengineering technologies to function as a durable and environmentally acceptable system for long-term stabilization of eroding stream banks.
Objective 4 – Evaluate the impact of the MRBS, the constructed wetland, and the soil bioengineering technologies on wildlife habitat and use.
Objective 5 – Evaluate the costs of establishing and maintaining the three components of the RiMS being demonstrated on the Risdal farm.
Objective 6 – Develop appropriate technology transfer materials and activities for farmers, policy-makers, farm groups, and others.
The project is located in the Bear Creek Watershed. The Bear Creek Watershed is located in North Central Iowa within the Des Moines Lobe, the depositional remnant of the late Wisconsinan glaciation in Iowa. On its eastern margin, the watershed is constrained by the Altamont moraine, which runs north-south in this area and is several miles west of the terminal Bemis moraine. The total length of Bear Creek is 34.8 km (21.6 mi) and it has 27.8 km (17.2 mi) of major tributaries before it empties into the Skunk River. The watershed drains 7160 ha (17,180 acres) of farmland, most of which has been subjected to tile-drainage during the last 40 years. About 85% of the watershed is devoted to corn and soybean agriculture. Prairie vegetation originally dominated most of the undulating to level topography, with the exception of forests that occurred along the lower end of the creek. Soils are well-drained to poorly drained and formed in till or local alluvium and colluvium derived from till. Roland, a town of 1,100 people, is the only community in the watershed and there are no major recreational areas.
Two different levels of research activity are taking place in the Bear Creek Watershed. The Leopold Center for Sustainable Agriculture’s Agroecology Issue Team is using the watershed to study the condition of the riparian zone at the watershed level. The team is developing a vulnerability map for the watershed that will identify critical riparian reaches along the creek that need restoration and/or modified management to reduce the impact of NPS pollution on Bear Creek. The long term goal of the project is to help farmers who own land along the creek develop riparian zone management systems that will intercept surface runoff and subsurface flow and will remove or immobilize sediment and agricultural chemicals before they enter the creek.
The Iowa State Agroforestry Research Team (IStART) is working on the Ronald Risdal farm in the watershed and developing a model riparian zone management system that includes a multi-species riparian buffer strip, a constructed wetland to intercept field tile water before it enters the creek, and soil bioengineering technologies to stabilize streambanks. This integrated management system could be used along the critical reaches of Bear Creek as well as other waterways in Iowa and the Midwest. The Agroecology Issue Team is using this site to demonstrate the riparian zone management system concept to farmers and to provide design specifications for similar buffer strip systems on their farms.
The MRBS site lies along a 1000 m (3300 ft) reach of Bear Creek on the 33 ha (80 ac) Risdal farm, approximately 2.4 km (1.5 mi) north of Roland. The farm has been owned by the Risdal family for several generations. As expected, there is a gentle topographic slope down to the creek. Corn, soybeans, and alfalfa hay are produced on this farm and the corn and soybeans are rotated on an annual basis. Pesticides applied on the farm have included Commence (chlomazone) in 1989 and 1991, Passport in 1993 and 1994, Pursuit Plus in 1995, Extrazine (atrazine and cyanazine) in 1990 – 1995, and Eradicane (EPTC) in 1990, 1992, 1994 and 1995. During the past 12 years, impregnated urea pellets have been applied at the rate of 134 kg /ha (120 lb /ac) on corn acres. On legume fields, 90 kg /ha (80 120 lb /ac) of 120-60-60 (N-P-K) are applied annually. Until 1988, livestock were also allowed to graze along parts of the stream riparian zone, which caused severe stream bank erosion and negatively impacted the riparian plant and animal community.
The MRBS site is set in Pleistocene sediment deposited by the Des Moines Lobe (Alden and Morgan Members) and Holocene age sediment overlying Mississippian age bedrock, which is composed primarily of limestone, dolomite, sandstone and shale. Perhaps the most surprising feature of the geology at the site is the depth to bedrock. Although maps provided by the Iowa Department of Natural Resources – Geological Service Bureau indicated that the Pleistocene sediment is probably 30 m (100 ft) thick and there are no visible bedrock outcrops near here, bedrock was encountered at depths of 6.7 m (22 ft) near the entrance to the farm and at depths of 3.7 to 4.6 m (12 to 15 ft) below the alluvium. Excavations of the creek bed for the weir installations indicated that weathered limestone and siltstone lie only 1.5 m (5 ft) below the channel. Shallow bedrock complicates the hydrogeology of the site to the extent that much of the hydrogeological research has been directed towards distinguishing groundwater flow in the shallow unconfined and the deeper bedrock aquifer.
Soils on this site belong to the Clarion-Storden-Coland association. Clarion soils are well drained and found on nearly level uplands. Storden soils are also well drained and found on sloping knobs and ridge tops. The Coland soils are poorly drained and found on nearly level riparian zones of small creeks. Terril and Zenor soils are minor components in this association. Most of the soils in this association can be farmed, if the slope is not too steep. This is the case on the project site, where all of the land, except that in the MRBS and in farm buildings, is being cultivated. Rill and sheet erosion on cultivated land and gully erosion in the drainage ways are major management concerns and can be major sources of NPS pollution.
The site has a continental climate typical of most of the Midwest. It is cold in winter and quite hot with occasional cool spells in summer. The average daily temperature in winter is -7 C (20°F) with an average daily minimum of -12 C (11° F). In summer the average temperature is 22 C (71° F) with the average daily maximum of 28 C (82° F). Five years in 10 the average growing season length is 157 days. Total precipitation is about 81 cm (32 in) per year although 1993 was an exceptional year with about twice the normal annual precipitation. About 75% of the annual precipitation falls in April through September, the growing season for most crops. There are frequent thunderstorms in summer and an average snowfall of 64 cm (25 in) each year. The sun shines 70% of the time in summer and 50% of the time in winter. The prevailing wind is from the northwest, although during the summer months the wind comes from the southwest. Tornadoes, intense thunderstorms, and hailstorms occasionally ruin crops.
Objective 1 – Demonstrate and quantify the ability of the multi-species, riparian buffer strip to filter, transform, and act as a sink for nonpoint source pollutants.
Description of the Riparian Management System
While a considerable body of evidence confirms that existing vegetated riparian zones have considerable ecological value and can be effective sinks for nonpoint source pollution (Castelle et al. 1994, Osborne and Kovacic 1993, Lowrance 1992, Cooper et al. 1987, Jacobs and Gilliam 1985, Lowrance et al. 1985, 1984, Peterjohn and Correll 1984), little information is available for restored or constructed riparian buffer systems. To demonstrate the benefits of properly functioning riparian zones in the heavily row-cropped midwestern United States, the Agroecology Issue Team of the Leopold Center for Sustainable Agriculture and the Iowa State Agroforestry Research Team are conducting research on the design and establishment of riparian management systems (RiMS). The purpose of these systems is to restore the essential ecological functions that these riparian areas once provided. Potential threats to water quality being addressed by these management systems include surface erosion (Figure 1), streambank and channel erosion (Figure 2), livestock grazing in the riparian zone (Figure 3), and agricultural tile drainage (Figure 4). Objectives of the riparian management system are to intercept eroding soil and agricultural chemicals from adjacent crop fields, slow flood waters, stabilize streambanks, provide wildlife habitat, and improve the biological integrity of aquatic ecosystems.
The initial research site is located on the Ronald Risdal farm along Bear Creek in a highly developed agricultural region of central Iowa. The farm has been owned by the Risdal family for several generations. Corn, soybeans, and alfalfa are produced on this farm with the corn and soybeans rotated on an annual basis. Until 1988, livestock were allowed to graze along parts of the riparian zone. Establishment of the RiMS on the Risdal farm began in 1990. The layout of the site is shown in Figure 5.
The riparian management system consists of three components; a, multi-species riparian buffer strip (MRBS), soil bioengineering technologies for streambank stabilization, and constructed wetlands to intercept and process nonpoint source pollutants in agricultural drainage tile water (Figure 6). The general multi-species riparian buffer strip layout consists of three zones (Figures 7 and 8). Starting at the stream bank edge, the first zone includes a 9 m (30 ft) wide strip of 4-5 rows of trees, the second zone is a 4 m (13 ft) wide strip of 1-2 rows of shrubs, and the third zone is a 7 m (22 ft) wide strip of native warm-season grass. This design is important because the trees and shrubs provide perennial root systems and long-term nutrient storage close to the stream while the grass provides the high density of stems needed to dissipate the energy of surface runoff from the adjacent cropland.
Fast-growing trees are recommended to provide a functioning multi-species riparian buffer strip in the shortest possible time. It is especially important that rows 1-3 (row 1 is closest to the streambank edge) in the tree zone include fast-growing, riparian species such as willow (Salix sp.), cottonwood (Populus deltoides), silver maple (Acer sacharinum), hybrid poplars (Populus sp.), green ash (Fraxinus pennsylvanica), and box elder (Acer negundo). The key to tree species selection is to observe native species growing along existing natural riparian zones and select the faster growing species. If height from the top of the streambank to the water level at normal flow (summer non-flood stage) is more than 1 m (3.2 ft) and soils are well drained, species such as black walnut (Juglans nigra), red oak (Quercus rubra), white oak (Quercus alba), white ash (Fraxinus americana) or even selected conifers can be planted in rows 4 and 5. The slower growing species will not begin to function as significant nutrient sinks as quickly as faster growing species. Other selections could be made based on species growing in neighboring uplands.
Shrubs are included in the design because of their permanent roots and because they add biodiversity and wildlife habitat. Their multiple stems also function to slow flood flows. The mixture of species that have been used by IStART include ninebark (Physocarpus opulifolius), red-osier (Cornus stonifera) and gray dogwood (Cornus racemosa), chokecherry (Prunus virginiana), Nanking cherry (Prunus tomentosa), hazel (Corylus americana), and nannyberry (Viburnm lentago). Other shrubs can be used, especially if they are native species and provide the desired wildlife/aesthetic objectives.
The grass zone functions to intercept and dissipate the energy of surface runoff, trap sediment and agricultural chemicals in the surface runoff, and provide a source of soil organic matter for microbes, which can metabolize the nonpoint source pollutants. A minimum width of 7 m (22 ft) of switchgrass (Panicum virgatum) is recommended because it produces a uniform cover and has dense, stiff stems that
provide a highly frictional surface to intercept surface runoff and facilitate infiltration. Other warm season grasses, such as Indian grass (Sorghastrum nutans) and big bluestem (Andropogon gerardii) and native perennial forbs also may be part of the mix. Because of its growth habit, switchgrass should be used where surface runoff is most severe.
One of the best ways to demonstrate the results of a restoration project is to keep a visual record of the progress of restoration from the beginning of the project. To that end two sets of photos (Figures 9-12) are provided to show visible changes on the site. Because this site was devoid of any significant plant cover other than closely grazed grass and cultivated fields, the change in vertical and horizontal structure of the vegetation community over the first six growing seasons has been very dramatic. This change in structure serves as a physical barrier to both water and wind movement across the buffer strip, provides a diverse wildlife habitat, dramatically changes the aesthetic impressions that visitors have of the site, and suggests that significant biomass can be produced that could provide potential commercial products for the landowner.
Water Quality Monitoring
An important goal of this project is to document and quantify the ability of the MRBS to filter, transform, and act as a sink for nonpoint source pollutants. To accomplish this, water quality is being monitored on a routine basis in the stream, agricultural drainage tiles, groundwater, and within the unsaturated (vadose) zone under the buffer strip. Stream samples are collected twice monthly during the growing season (March through October) and monthly during November through February from three locations within the research site. Samples are collected at the same time from five agricultural field tiles located within the research site. Samples are assayed for nitrate-nitrogen, atrazine, pH, dissolved oxygen, and total suspended solids. Stream and drainage tile discharge are determined at the time of sampling. Deeper piezometers are sampled on a quarterly basis and assayed for nitrate-nitrogen, atrazine, and chloride.
Five transects across one section of the MRBS are being intensively monitored to examine the physical, chemical, and biological processes that occur there. Each of these transects has three nests of sampling devices consisting of a “mini-piezometer” located below the water table, a zero-tension lysimeter at 15-25 cm (6-10 in) below the surface, two porous-cup tension lysimeters at 0.3 m (1 ft) and 1 m (3 ft), and a soil tensiometer at 30 cm (12 in). These nests are located at the crop field-switchgrass interface, within the shrub zone of the buffer strip, and within the tree zone of the buffer strip. During the growing season an additional set of lysimeters is installed within the cropped field along each of the five transects. During 1995, three additional transects containing tension lysimeters at two depths were established in a crop field adjacent to the Risdal farm where the operator cultivates nearly to the streambank edge. Lysimeter nests were installed at the same distances from the stream as those within the MRBS. These transects allow for the comparison of buffer strip function to an area where cropping occurs immediately adjacent to the stream.
During the growing season all instruments within the intensively monitored plots are sampled repeatedly after large precipitation events until the water content of the soil has returned to near field capacity. At other times, samples are collected on the same schedule as stream samples. Water level within the mini-piezometers and several piezometers is measured weekly during the growing season and twice monthy during the months of December – February. Water samples are also collected at the same time from these instruments.
Plant samples of each species in the MRBS, the crop plants growing adjacent to the MRBS, and the cool season grasses within the control plots are collected at the end of each growing season. These samples are assayed for nitrate-nitrogen, ammonia, total (Kjeldahl) nitrogen, and atrazine. A continuously-recording, CR-10 controlled weather station monitors solar radiation, air and soil temperature, relative humidity, wind speed and direction, precipitation, and soil moisture.
Initial results show that nitrate concentrations in the vadose zone are much lower across the buffer strip than within the adjacent cultivated field during both 1994 and 1995 (Figures 13 and 14). Concentrations of nitrate-nitrogen measured within the cropped field were much higher during 1995 than 1994, likely due to the application of urea fertilizer to corn planted in 1995. Regardless of the nitrate-nitrogen concentration measured within fields, however, average concentrations measured within the unsaturated zone nearest the stream never exceeded 3 mg /L.
In contrast, concentrations of nitrate-nitrogen measured in the vadose zone within a field cropped nearly to the stream edge showed no reduction nearer the stream (Figure 15). Differences in the absolute values of nitrate-nitrogen within crop fields (Figures 13 – 14) are likely the result of differences in fertilizer management and soil types. The important distinction between these two sites is the buffering of nitrate-nitrogen concentrations within the vadose zone near the stream provided by the MRBS. In areas where shallow groundwater contributes significantly to stream flow, this buffering function is important in reducing nitrate-nitrogen loads to streams. The lower nitrate-nitrogen concentrations in the vadose zone across the buffer strip are likely combination of the lack of cultivation and fertilizer application within this zone as well the transformation and loss of nitrogen moving through the buffer strip.
Atrazine concentrations in the vadose zone were also much lower across the buffer strip than within the adjacent cultivated field during both 1994 and 1995 (Figures 16 and 17). Atrazine concentrations within the cropped field were much higher in 1995, due to the application of Extrazine when the field was planted to corn. Again, the lower atrazine concentrations in the vadose zone across the buffer strip are likely a combination of the lack of application within this zone, as well the transformation and loss of atrazine moving through the buffer strip. In both cases, in areas where this vadose zone water contributes to streamflow, the presence of the buffer strip will greatly reduce atrazine and nitrogen loadings to the stream. These data do not necessarily reflect the quality of water moving through the shallow groundwater table below the vadose zone. It is possible that agricultural chemicals are leaching through the vadose zones into the groundwater in the crop field and the moving below the MRBS to enter the stream with baseflow.
In assessing the importance of shallow groundwater contributions of agricultural chemicals to the stream, it is important to document the dynamics of the shallow groundwater that may be moving below the MRBS. To accomplish this, minipiezometers were installed in the summer of 1994 across each of the five intensively monitored transects. These instruments are monitored for water level and water quality as described above. The goal of this monitoring is to produce a detailed flow model describing water and chemical movement in the shallow groundwater under the MRBS.
Initial monitoring has provided data to construct preliminary contour maps of groundwater table elevations across the buffer strip (Figures 18 and 19). These maps illustrate that during most times of the year the water table slopes gradually upward away from the stream, under the MRBS and adjacent crop field. During these times this reach of stream would be gaining groundwater as baseflow as indicated by flowlines moving perpendicular to the water table contour lines. In this reach the stream would be considered an effluent stream. A full season of water level monitoring during 1995 also indicates a substantial seasonal flux in the water table with depths to groundwater varying by nearly 1m (3.2 ft). Continued and expanded monitoring is required in order to construct the detailed flow models necessary to accurately describe the shallow groundwater flow beneath the buffer strip.
Nitrate concentrations in the shallow groundwater are highly variable between adjacent transects, and suggest that nitrate contained within shallow groundwater may be moving preferentially across the buffer strip at a depth below the zone sampled by the lysimeters (Figure 20). In contrast, atrazine concentrations are always near detection limits, suggesting little movement of this chemical with the shallow groundwater.
We are expanding our efforts to accurately characterize groundwater and chemical movement across the buffer strip. To this end, we have been successful in obtaining a three-year grant through the USDA National Research Initiative Competitive Grants Program to support these efforts. Initial data collection supported through the Agriculture in Concert With the Environment Program has been instrumental in obtaining these additional resources. The ultimate goal of this research is to characterize the site specificity of nitrate retention and transformation within the streamside buffer strip in order to make credible management recommendations as to their placement and effectiveness.
Objective 2 – Develop a small wetland to intercept and process field tile drainage.
A characteristic of North Central Iowa and much of the prairie pothole region is the presence of an extensive network of subsurface tile drainage. Such tile drains often dominate increases in stream discharge and provide a direct path to surface water for nitrate or other agricultural chemicals that move with shallow groundwater. In such instances, constructed wetlands that are integrated into new or existing drainage systems may have considerable potential to remove nitrate from shallow subsurface drainage (Crumpton and Baker 1993, Crumpton et al. 1993).
To demonstrate this technology, a small, 270 m2 (2900 ft2) wetland was constructed to process field drainage tile water from a 4.9 ha (12 ac) cropped field. The size and shape of the wetland were designed to fit into the 20 m (66 ft) MRBS. Construction of the wetland was completed in early June, 1994. The wetland was constructed by excavating soil near the creek and raising a low berm (Figure 21). Because the site chosen for the wetland contained some alluvial sand, the bottom of the wetland was sealed with clay. Organic soil was then replaced as the top layer. An agricultural drainage tile was excavated and rerouted to enter the wetland at a point furthest from the creek, forcing the water to travel through the wetland before entering the surface waters. A gated water level control structure at the wetland outlet provides complete control of the level of water maintained within the wetland. Cattail (Typha glauca) rhizomes were collected from a nearby wetland during early spring when the shoots had just begun to elongate, and stored in a cooler until planting. These cattails were planted in early June at a spacing of approximately 0.6 x 0.6 m (2 x 2 ft) (Figures 22 and 23). Growth during the initial season was dramatic (Figure 24). The cattails spread rapidly throughout the wetland and many achieved heights in excess of 2 m (6.4 ft). During the following winter and early spring however, many of these cattails were removed by muskrats. As a result, much of the wetland had to be replanted during the spring of 1995. Big bluestem (Andropogon gerardii), Indiangrass (Sorghastrum nutans), gray-headed coneflower (Ratibda pinnata), and black-eyed susan (Rudbeckia hirta) were planted on the constructed berm to provide vegetation diversity. Establishment of these native grasses and forbs was very successful with all species flowering by the second year. Willow cuttings (Salix sp.) were installed on the side of the berm facing the stream for stabilization.
Water samples at the inlet and outlet of the wetland are collected through the use of automated water samplers. When temperatures prohibit the use of the automated samplers, the inlet and outlet of the wetland are sampled along with routine stream and tile sampling. In 1994, when the field being drained by the tile feeding the wetland was in corn, water samples are assayed for nitrate-nitrogen and atrazine. In 1995, when the drained field was in soybeans, water samples were assayed for nitrate only.
In 1994, inflow concentrations of nitrate-nitrogen in the tile drainage fluctuated between 5 and 10 mg /L NO3–N (Figure 25). In contrast, outflow concentrations were substantially lower during most times. Exceptions to this were in early August and mid-September when large precipitation events increased tile discharge substantially and reduced the residence time of nitrate laden waters within the wetland. Note also that nitrate concentration in the outflow consistently increased during late September and October, reflecting the effects of colder temperatures on denitrifying bacteria.
In 1995, inflow concentrations of nitrate-nitrogen in the drainage tile water fluctuated between 7 and 11 mg /L NO3–N (Figure 26). Similar to 1994, outflow concentrations were substantially lower during most times. Notable exceptions were during early May and early July, again when large precipitation events increased tile discharge substantially and reduced the residence time of nitrate laden waters within the wetland. Precipitation at the research site during the months of July and August, 1995 was substantially below normal. As a result, outflow from the wetland ceased by September 1, and the wetland was dry shortly thereafter.
Concentrations of nitrate-nitrogen in the both the drainage tile water and the outflow decreased rapidly over this period.
Experimental studies by the Iowa State University Wetlands Research Group using wetland mesocosms have confirmed the considerable capacity of freshwater wetlands to remove nitrate (Crumpton et al. 1993) and confirmed that denitrification is the dominant loss process for externally loaded nitrate (Isenhart 1992, Isenhart and Crumpton in prep.). The studies also demonstrate that wetlands containing a large amount of standing vegetation and a large buildup of decaying plant litter will be more efficient in nitrate removal, given sufficient contact time between pollutant laden water and the substrate (Crumpton and Isenhart in prep.). This indicates that wetlands will likely become more efficient at removing nitrate after several growing seasons worth of litter accumulation and may likely take several years to reach a steady state with respect to their nitrate removal capacity.
Rates of nitrate loss in the wetland at the Risdal research site during 1994 and 1995 ranged from 0.3 to nearly 1 gram of NO3–N per square meter of wetland per day. These are comparable to loss rates observed within the wetland mesocoms during the first year after establishment. However, there was little increase observed in nitrate loss rate in the Risdal wetland during 1995. One factor contributing to this was the loss of vegetation within the wetland to muskrats. This prevented the expansion of standing vegetation and buildup of dead plant litter, which would promote higher nitrate loss rates. It is expected that the nitrate removal capacity of the wetland will increase as the wetland matures and accumulates this litter layer of dead plant material. Removal rates of nitrate within the wetland can be expected to increase in 1996 as the vegetation density increases.
The ratio of wetland surface area to area of crop field drained for the Risdal wetland is 1:180. Previous studies suggest that a mature, one hectare wetland could remove significant amounts of the nitrate in water draining approximately 100 ha of corn at moderately high N application rates (Crumpton et al. 1993, Isenhart 1992). The Risdal wetland is, therefore, below this benchmark ratio, and it remains to be seen what the maximum retention capacity for nitrate will be once the wetland reaches maturity. Models have subsequently been developed of areal nitrate flux which can be combined with models of wetland hydrology to produce general models of nitrate loss and assimilative capacity for freshwater wetlands (Crumpton and Baker 1993). These models will be utilized to interpret data from the Risdal wetland.
In the case of atrazine, concentrations were very low (< 0.5 μg /L) in both the tile inflow and outflow to the stream for most of the monitoring period during 1994 (Figure 27). The notable exception to this was in late September, when inflow concentrations in the drainage tile increased to over 1.5 μg /L. During this time atrazine concentrations in the wetland outflow remained below 0.75 μg /L as a result of both dilution and retention within the wetland.
Objective 3 – Demonstrate the ability of a combination of willow posts, stakes, and cuttings to act as a durable and environmentally acceptable system for long-term stabilization of eroding stream banks.
The objectives of streambank stabilization efforts are to reduce sediment loading to the stream originating from streambank erosion, and to stop the movement of the bank. In some cases, bank movement may be encroaching on fields, bridges, and roads. In other cases, channelized stream sections may start to again meander. The stabilization of streambanks is accomplished by changing the steep angle on actively eroding banks to a gradual slope on which woody or other perennial plants may seed themselves or be planted. Deeply-rooted plant material will help hold the soil of the streambank in place. Woody plant roots have the advantage that they are perennial and provide long-term strength to the soil, even during the winter and early spring. Woody stems of willow and other species provide a dense frictional surface that slows the water impacting the bank and moves the rapidly moving current out away from the streambank. The slower water moving through the stems drops sediment. The accumulating sediment changes the slope of the bank and provides sites for other native plant establishment. A characteristic of perennial grasses that become established along the bank is that they do not slow the water as much and typically lay down along the bank, allowing rapid movement of water while yet protecting the bank. This use of grasses may be important in reaches where there is concern that channel flow should not be slowed.
Stabilization of streambanks using bioengineering methods also provides wildlife habitat improvements. Aquatic habitats may be improved when shaded conditions stabilize water temperature. Inputs of organic matter from the litter of the overhanging plants also provide substrate for aquatic invertebrates. In some cases, woody debris dams, which may develop from fallen stems or beaver dams, may be beneficial. In other cases, especially in some cold water fisheries, the presence of woody stems provides material for beaver dams that produce pools in which accumulating sediment covers gravel streambeds.
Streambank bioengineering projects must consider the objectives of the landowner, the size of the stream, the stream fishery, the stability of the channel bottom, and the severity of the streambank erosion. Each design must be site specific. The goal of this project has therefore been to demonstrate a number of different designs to address the many variables that must be considered at each project site.
For small streams, those in which the top of the bank is 1.2 m to 1.8 m (4 ft to 6 ft) above the normal water surface, stabilization can often be accomplished simply by installing live posts, stakes, and cuttings along the bank toe and in the vertical wall of the streambank. On slightly higher banks or larger streams, dead tree revetments can also be installed to stabilize the toe of the bank. Willows are recommended because they root easily and multiply quickly under the often harsh conditions found along an eroding streambank. However, other species can be used. Cottonwood (Populus deltoides) cuttings may root well in the upper banks and dogwoods (Cornus spp.) may be used above the willow posts. Use of dogwood reduces the shading of the stream and may discourage beaver activity.
For this grant, variants of two different methods of bioengineering were developed on four sites. To demonstrate the use of willow posts and tree revetments, two 80-100 meter long stream bank willow plantings and revetments have been established on the outside bends of two severely eroding stream banks on the Risdal project site (Figure 5). On the first site, willow stakes and posts were manually pounded into the stream bottom, the toe of the bank, and on the vertical wall (Figures 28 and 29). The willow cuttings were collected during the dormant season by harvesting willow stems and cutting them into 0.6 – 1.2 m (2 – 4 ft) lengths. During the second year, a revetment of silver maple bundles was added along the toe of the bank. The silver maple revetments are composed of bundles of 3-8 year old trees that were wired together and then piled and anchored to fence posts that were pounded into the bottom of the stream bank. On the first site, revetments were only added along the toe of the bank. Figures 30 and 31 show the response of this bioengineering technique after 2 and 4 years.
On the second site, the revetments were piled higher to protect the 2.1 – 2.4 m (7-8 ft) high vertical bank (Figure 32 and 33). On both sites, willow posts and stakes were manually installed into and around the revetments and in the rest of the vertical bank. These revetments of living and dead trees provide a dense frictional surface to dissipate the energy of the stream and allow the willow cuttings to become established. The willow posts and stakes sprout quickly (Figure 34 and 35), producing a vegetated surface that adds a living and dynamic frictional surface to slow the flow and protect the bank. Both of these sites have withstood major flood events, including the major floods of 1993. Costs associated with installation of these systems are presented under Objective 5.
Along streambanks that are greater than 1.8 m (6 ft) in height or on larger streams, additional techniques may have to be used, including the use of some non-biological material. To demonstrate these techniques, two additional sites, a 76 m (250 ft) long site on the Larson property and a 46 m (150 ft) site on the Risdal property, have been installed. Figures 36 – 43 show the installation of the system on the Larson property. Major considerations for that installation are listed below.
• Because the streambank was steep (Figure 36), a backhoe was used to slope it to a 1:1 (horizontal:vertical) angle (Figure 37). A slope of 2:1 may be required for taller streambanks.
• The toe of the slope was stabilized by cabling Eastern redcedar to fence posts (Figure 38). Alternatively, the Eastern redcedar could have been cabled to willow posts installed in the streambed. After the first storm event the redcedars are buried with enough sediment that they will no longer move. A shallow trench 45 – 60 cm (1.5 – 2 ft) wide and 15 – 20 cm (6 – 8 in) deep was dug at the base of the slope in which to bury the end of the geotextile installed to protect the face of the slope. A waterway grass seed mixture was spread over the exposed bank at a rate of 5.6 Kg /ha (5 lbs /ac).
• The geotextile was installed up and down the slope, beginning at the downstream end of the site. The top sheet of geotextile was overlapped 15 – 30 cm (1/2-1 ft) over the bottom sheet and degradable staples were inserted along the overlapped area. Additional wire staples were installed on a 0.6 x 0.6 m (2 x 2 ft) spacing over the whole slope (Figure 39). If the slopes had been sloped to 2:1, geotextile may not have been necessary. Alternatively, more willow and/or dogwood cuttings would be planted.
• Live willow fascines were prepared and placed in the trench along the bottom of the slope (Figure 40). This securely anchors the geotextile to the soil. The fascines were covered with soil allowing only a small portion of the willow to be exposed to light. The willow in the fascines developed roots and sprouts, which effectively anchored the mat to the bottom of the bank. Figure 41 shows the streambank stabilization structure during higher water that occurred during construction.
• Willow posts were installed through the fascines and in three rows along the bottom of the bank at a spacing of 0.9 m (3 ft) between trees and 0.9 – 1.2 m (3 – 4 ft) between rows. Additional stakes were installed above the posts to the top of the slope. Another shallow trench was prepared at the top of the slope, into which the top end of the geotextile was buried. Finally, a multi-species buffer strip was planted along the top of the slope (Figure 42). Growth after two months showed grass coming through the mat and sprouting of the willow (Figure 43).
Installation of the soil bioengineering demonstration on the Risdal property is shown in Figures 44-49. The major differences in this installation are that rock rip rap was used to stabilize the toe of the slope instead of Eastern redcedar, and no fascines were used to tie the geotextile to the slope. Instead, the geotextile was buried in a trench dug along the bottom of the slope and willow posts installed along the trench. The trench is wide enough to form a lip on which a person could walk to fish the stream. The grass and willows on this installation have grown exceptionally well. While this installation may be more than was necessary to protect this streambank, it was installed to provide a demonstration on the Risdal property where most of the field tours are taken and where the other RiMS components are demonstrated.
The effectiveness of these streambank bioengineering options is being monitored by comparing treated stream sections with several unprotected banks of similar curvature and length along Bear Creek. Permanent cross sections have been established and surveyed in order to measure the movement of the creek. Initial results are very encouraging and visual observations suggest bank collapse has been dramatically reduced.
Three other uses of bioengineering have also been demonstrated on the project sites. Figure 50 shows the use of only Eastern redcedar as a bank stabilization technique. After installing rock rip rap for toe control, Eastern redcedar trees were cabled to the vertical bank. This system was installed in 1995 and seems to be holding. Figure 51 shows both the more intensive design that includes the geotextile and the simpler Eastern redcedar installation. Both systems are being monitored to see how effective each is in maintaining streambank stability.
Figure 52 shows the effectiveness of willow stakes that were installed on a four foot high bank just downstream from a bridge on the Risdal farm. The bridge was washed out after the 1993 storms. After it was rebuilt, the channel cross-section was changed enough so that the bank on the right started to show accelerated erosion. Willow stakes of 0.6 – 0.9 m (2-3 ft) length were installed to slow the erosion. This low cost method is very effective, if installed when the problem is first evident.
Figure 53 shows the use of willow posts installed across a gully. The posts are installed as close together as possible and bound together with twine. An Eastern redcedar is cabled into the gully upslope of the willow to slow the water before it reaches the willow posts. This installation was completed in May of 1995.
Soil bioengineering technologies are proving to be very effective at streambank stabilization on second and third order streams. Further testing and demonstrations are needed, however, on larger size rivers. We will be conducting such a test in 1996 on the Volga River in Northeast Iowa. Costs for the soil bioengineering systems that have been described are presented under objective 5.
Objective 4 – Evaluate the impact of the MRBS, the field tile wetland, and the stream bank willow planting on wildlife habitat and use.
Wildlife habitat in much of the corn belt of the Midwest has been impacted greatly by intensive row crop agriculture. Riparian areas that once had diverse tree, shrub, and native grass cover are now grazed or cultivated. Such areas provide little nesting cover or food to maintain a diverse wildlife population. The riparian management system being developed on Bear Creek was specifically designed in part to enhance wildlife habitat. For example, shrubs have been incorporated in the design for their diversity in habitat as well as for their food production.
To document its habitat value, bird species composition within the MRBS was assessed and compared with species composition in a contiguous, channelized section of stream with little riparian cover (downstream) and in an upstream section which was planted to a MRBS early in 1994 (Strum farm). The newly planted site contains some tight meanders along which willows and other trees and shrubs were established. It therefore had some available habitat even before the MRBS was planted.
The three study areas were divided into 17 fixed observation points beginning with the Strum farm and numbering downstream (Figure 54). Location of observation sites were based on differences in dominant cover, i.e. Site 1 was located in unmanaged, mixed grasses; Site 12 was located in an area of willows and a wetland. Observations were extended to a radius of 50 m (160 ft) from the center of each site except for sites 16 and 17. This exception was made because of the homogenous plant structure and unbroken visual distance along this portion of Bear Creek (brome grass buffer strip 5 m wide).
Observations were made over a total of 10 days beginning 15 June 1994 and ending 11 July, 1994. Starting observation sites were varied each day as a means of balancing patterns in bird species activity associated with microclimate and onset activities (Karr and Freemark 1983). Species observations were noted from two points within each site for a total of 10 to 15 minutes. Species were counted as present if either visually observed or their song was heard. All observations were made by the same individual, and only those species positively identified were counted. No attempt was made to measure species density. The presence of nesting was noted, but no intensive search for nests was undertaken.
Results demonstrate that MRBS construction increased bird species diversity dramatically and in a short period of time. On average, four species per day were found on the channelized section, 14 species per day were found on the newly planted MRBS (Strum farm), and 18 species per day were found in the four-year old MRBS on the Risdal farm (Figure 55). These observations translate into nearly 4.5 times more bird species using the MRBS site compared to the channelized reach. A two-sample comparison at the p<0.05 level indicate that these differences in bird species diversity are significant.
The total number of bird species observed throughout the study period was also much greater within the MRBS site (Table 1). Within the channelized section, a total of 8 species were observed throughout the study period. Within the newly planted MRBS site (Strum farm) and the four-year old MRBS (Risdal farm), these numbers increased to 24 and 30 species, respectively.
Sorenson’s coefficient of community was applied to assess differences in bird communities observed in each of the three management areas along Bear Creek. Sorenson’s index is defined as cc=2c/(s1 +s2), where cc is the coefficient of community, c is the number of bird species held in common in two sites to be compared, s1 and s2 are the total numbers of species accounted for in each site. Results indicate that there was a strong similarity between bird communities using the Strum and Risdal sites, as indicated by a Sorenson value over 86%. In contrast, there was little similarity in bird communities observed within the channelized area compared to the Strum and Risdal sites, as indicated by Sorenson values of only 42% and 41%, respectively.
Many factors will affect the diversity of bird species observed in a given area. These include the size of the habitat area, individual species’ habits, land management practices, predation, time of day, weather, and others (Smith and Shugart 1987). Analysis of community similarity infers that the Strum and Risdal areas share factors that may be influencing bird species. These factors might include the width of habitat area, vegetative structure and species diversity, similarities in older, woody vegetation, increased foraging areas, or even less tangible influences attributed to such factors as increased invertebrate assemblages (Smith and Shugart 1987, Rafe et al. 1985). One factor contributing to similarity between the Risdal and Strum sites is the presence of existing woody (tree and shrub) vegetation on the Strum site.
Dissimilarity in bird species composition between the channelized area and the Risdal area may be attributed to the width and structure of the riparian vegetation. The MRBS established on the Risdal farm is nearly four times as wide as the grass-only buffer of the channelized area. These results would agree with those of Stauffer and Best (1980) who found that “bird species richness increased with the width of wooded riparian habitat.” The lower vegetation complexity found along the channelized portion of Bear Creek may also negatively affect bird species by exposure to greater daily temperature/precipitation changes, decreased food availability, increased vulnerability to predation, and other microhabitat variations (Ambuel and Temple 1983, Stauffer and Best 1980).
Several factors that may have affected observed species diversity were neither vegetational nor climatic. For example, several locations within the study area were periodically mowed to aid the establishment and growth of planted tree and shrub species. Another factor to be considered is the presence of several free-roaming dogs within the Risdal area. The ability of the dogs to locate and rouse nesting species was witnessed several times during the observation period. On observation days, care was taken to avoid attracting the dogs by entering the study area away from the Risdal site proper. Both of these factors may have negatively impacted ground-nesting bird species on the managed areas; thus we regard these species diversity measures to be conservative.
Vegetation diversity within the MRBS appeared to directly effect the patterns in diversity. For example, observation sites situated on either side of Risdal wetland possessed a greater species richness. Similarly, an observation site containing two large, standing dead trees attracted a very diverse composition of birds. Also, bird species observed in and around the dense willow plantings established for streambank stabilization were seldom found elsewhere. These species include Parus atricapillus (Black-capped Chicadee), Carduelis tristis (American Goldfinch), and Spiza americana (Dickcissel). These findings are consistent with other studies (Rafe et al. 1985)
Although community indices are not widely accepted as the sole indicators of habitat complexity, this study strongly suggests that the multi-species riparian management system positively influences bird species diversity. Future areas of study should include analysis of management effects on breeding birds as well as examination of the correlation that apparently exist between bird species diversity and the various vegetation components of multi-species management.
[Table 1 shows bird species noted in each study area in early summer along Bear Creek in central Iowa. Since it is not possible to render this table here, we offer a list of all the species observed at all sites:]
Agelaius phoeniceus, Red-winged Blackbird
Anas discors, Blue-winged Teal
Carduelis tristis, American Goldfinch
Ceryle alcyo, Belted Kingfisher
Charadrius vociferus, Kildeer
Cistothorus platensis, Sedge Wren
Cyanocitta cristana, Blue Jay
Dendroica petechia, Yellow Warbler
Dolichonyx oryzivorus, Bobolink
Geothlypis trichas, Common Yellowthroat
Hirundo rustica, Barn Swallow
Melospiza melodia, Song Sparrow
Molothrus ater, Brown-headed Cowbird
Parus atricapillus, Black-capped Chickadee
Passerculus sandwicensis, Savannah Sparrow Phasianus colchicus, Ring-necked Pheasant
Pooecetes gramineus, Vesper Sparrow
Progne subis, Purple Martin
Quiscalus quiscula, Common Grackle
Sayornis phoebe, Eastern Phoebe
Spiza americana, Dickcissel
Spizella passerina, Chipping sparrow
Spizella pusilla, Field Sparrow
Sturnella magna, Eastern Meadowlark
Sturnus vulgaris, Euopean Starling
Tachycineta bicolor, Tree Swallow
Toxostoma rufum, Brown Thrasher
Turdus migratorius, American Robin
Zenaida macroura, Mourning Dove
Mean species per day:
Objective 5 – Evaluate the costs of establishing and maintaining the three riparian management systems being demonstrated on the Risdal farm.
Multi-species Riparian Buffer Strip
Costs of establishment and maintenance of each of the components of the RiMS are being determined on an ongoing basis. In addition, Mr. Risdal is continuing to supply his costs for producing corn and soybeans. Costs for establishment and maintenance of the multi-species riparian buffer strip have been estimated using 1994 and 1995 costs and prices. Tree seedling costs were based on prices from the Iowa Department of Natural Resources State Forest Nursery. Switchgrass seed costs were based on local agricultural seed supplier prices. Site preparation costs were based on the Iowa State University Extension Service 1994 Iowa Custom Farm Rates adjusted for inflation. The site preparation for trees and shrubs assumes a 1.5% concentration of glyphosate applied in a narrow strip and for switchgrass either cultivation and disking or a broadcast of glyphosate before drilling. Planting and maintenance costs were based on 1994 local custom prices for those services. Maintenance costs were based on spot spraying glyphosate and some mowing for competition control in the tree and shrub rows for the first 5 to 8 years and harvesting (or burning) of switchgrass on an annual basis.
Establishment costs reported here are for a 66 ft (20 m) wide multi-species riparian buffer strip which has 8 ft. (2.4 m) between rows and 4 ft (1.2 m) between trees within a row. The total establishment cost is approximately $538 /ac. To provide a conservative estimate, the costs used are “high-end” costs. For example, it is assumed that the seedling cost is $0.22 each. Some Midwestern private nurseries charge $0.12 for the same tree seedling. The cost of planting varies as well from a high of $0.20 per seedling to $0.105 per seedling. Because the plant material and planting costs are the predominant cost components, actual per acre costs are likely to not exceed the stated costs. Tables 2a and 2b present the establishment costs for various riparian buffer strip designs to be established on agricultural land that is currently being cropped or pasture land.
The estimated establishment and maintenance cost does not include any existing governmental cost-share or other subsidy. Currently, there are several cost-share programs available that will cover up to 75% of these expenses. The Stewardship Incentive Program (SIP) administered by the Iowa Department of Natural Resources will cost-share up to 75% of the establishment cost of a buffer strip not to exceed $315 per acre. Also, SIP will provide 75% of the cost of fencing the buffer strip to keep out livestock, if necessary, not to exceed $45 per acre. Finally, SIP will provide 75% of the cost of shelters for trees planted in the buffer strip, not to exceed $150 per acre. Additionally, in Story County, IA, Pheasants Forever (a non-governmental organization) will cost share another 15% for the purchase of plant materials used in a buffer strip.
A multi-species riparian buffer strip can qualify as a “Forest Reserve” under the Iowa Forest Reserve Law. This means that the land on which a qualifying buffer strip exists will not have property taxes. To qualify a multi-species riparian buffer strip must contain the equivalent of 200 trees /ac, be more than 2 ac (0.8 ha) in size, and have livestock kept out of it. For Iowa this means a cost-savings of roughly $15 – 20 per acre per year.
Tables 3 a and 3b present the discounted costs of establishing 1 acre of riparian buffer strip on cropped land and grazed (pasture) land over a 20 year period. Note that the 1994-5 average rental rates for cropped and pasture lands for Central Iowa were used to determine the total present value of costs. By including the rental rates, the primary opportunity cost of installing a riparian buffer strip on existing agricultural land is included.
If a riparian buffer strip was established along the main channel and tributaries of Bear Creek at either 33 ft., 66 ft., or 100 ft wide on both sides of the stream, how much would the farmers and society have to pay? Table 4a presents the estimates of establishing and maintaining such buffer strips over a 20 year period. Clearly, the wider the buffer along Bear Creek, the greater the cost. The question then becomes whether the value associated with the expected flow of environmental and market benefits from the buffer strip greater than this cost, including the opportunity cost of not farming the land immediately adjacent to Bear Creek. When biomass from trees and switchgrass are valued over a 20 year period at $15 per ton, total present value of cost is reduced by 6 percent at a 5% discount rate. Although not included in the analysis, hunting and aesthetic value, and cost-share options from non-governmental organizations such as Pheasants Forever can further reduce the total cost to the farmers and society for buffer strip protection that complements best management practices on the uplands. Establishing a 66 ft wide buffer on Bear Creek would convert about 445 acres of currently cropped or pastured land.
Table 4b illustrates what the cost would be if the protection effort was focused on the lands adjacent to Bear Creek that are classified as potential or highly erodible lands (HEL). Establishing the 66 ft wide buffer would convert only 45 acres of cropped or pastured lands in the watershed. Obviously the costs of protecting HEL lands within the watershed are much smaller and so too are the expected benefits from reducing non-point source pollutants.
The following cost estimates are based on the streambank bioengineering portions of the RiMS project located in rural Story County, Iowa. Over the preceding three years, IStART and the Agroecology Issue Team have installed seven different streambank bioengineering systems on Bear Creek, a second order stream that is a part of the Skunk River watershed. The streambank bioengineering systems that were added to Bear Creek were designed and installed by Richard Schultz, Joe Colletti, Tom Isenhart, Chuck Rodrigues, and numerous Iowa State University students. Material and installation costs were recorded during the installation of each of the different streambank bioengineering systems.
This portion of the report is organized by presenting a short explanation of how and why to install each system followed by a table listing all materials required to install such a system. The materials are then converted to a cost per linear foot of streambank. Each table is followed by a list of the citations of sources that were used for the costs cited.
Some assumptions were made for transportation, cost of tools, and labor. Transportation is based upon the number of miles that willow, Eastern redcedar, and silver maple are carried to the installation site. It is assumed that these trees can be found within five miles of the installation site. If they are not within five miles, the cost per linear foot will increase. Likewise if they can be located closer than five miles the cost per linear foot will decrease.
The cost of the small tools, hammers, gloves, shovels, etc., are calculated on the basis of the average life expectancy of each tool. For example, hammer costs are based on a five-year life expectancy. A small equipment cost was calculated for each different component of the streambank bioengineering systems and added into the cost per linear foot. For example, separate costs were calculated for willow post cutting and installation, preparation and installation of fascines, cutting and installation of Eastern redcedar, and installation of the geotextile. For each of the seven streambank bioengineering systems that were installed, equipment costs were added based on the number of components that were used in the system. For example, if a fascine and willow posts were used, the cost of small equipment for each of them was added into the total cost of the system. This accounting for the same small equipment twice would increase the cost per linear foot when actually the cost per linear foot should go down. The cost for small equipment should decrease, because the equipment was already purchased and available for use with both components. When summing the cost per linear foot for a streambank bioengineering system that has several different components, the cost per linear foot may be inflated. Costs per linear foot were calculated in this manner to best show estimates of cost per linear foot for each individual component of the system.
Costs that are incurred for labor to collect, prepare, and install streambank bioengineering systems can be greatly decreased if volunteers can be found. Labor can come from hiring persons at an hourly rate or contacting local conservation groups that may volunteer their time. Conservation groups and interested private persons may help install a streambank bioengineering system so that they gain experience with constructing such a system. Whenever possible conservation groups should be contacted for help with installation so that the cost is reduced. However, as acceptance of these systems becomes more widespread, there will be a need for training contractors who will routinely and professionally install these systems.
All of the listed streambank bioengineering systems should be planted in the spring, from late March to early May. Nearly all systems use live willow and other material that should be planted early to survive through the summer.
Geotextiles, or fabric manufactured from natural fibers such as coconut fiber, are used to protect the exposed streambank from rainfall impact and high channel flows after reshaping has occurred. Reshaped streambanks are very susceptible to erosion because the soil has been disturbed. To reduce damage by erosion, the newly sloped streambanks may be covered with a natural fiber fabric. Trenches are dug at the top and bottom of the streambank to install the edges of the fabric so that it cannot be ripped out during high streamflow. Willow posts or stakes are planted through the fabric in the trenches and waterway grass seed mixes are sown under the fabric to ensure quick revegetation of the site. The fabric is designed to decompose in two or three years, well after the grasses, shrubs, or trees have become established.
The use of geotextiles as a component of streambank bioengineering constitutes a major cost per linear foot. The cost of the fabric, based on two projects in central Iowa established in 1995 on Bear Creek, was $2.34 per linear foot. This represents 62% of the total cost of a particular installation. Another substantial cost in this component of a streambank bioengineering system is the labor. The labor cost for installing a geotextile is $1.01 per linear foot or twenty-seven percent of the total cost per linear foot. While there are other fabrics that could be used, we only have data on the coconut geotextile.
Site Preparation Costs
Site preparation entails reshaping the streambank with a backhoe. If the top of the streambank is higher than 6 ft above low flow in the channel and the walls are vertical or nearly so, then the streambank must be reshaped. Without reshaping, the streambank will continue to slough until a slope angle develops on which vegetation can become established. Stability can be achieved through natural processes over time as the stream and streambank have time to equilibrate. This process of equilibrating takes a very long time during which the channel may move significantly. It is also possible that the system will continue to be in a state of flux and stability may never occur, especially if the banks are high and vertical. To hasten stabilization a backhoe can be used. The streambank is usually reconstructed to a 2:1 ratio of horizontal to vertical length. At this ratio and with vegetation cover, a stable slope can be developed.
The cost per linear foot of reshaping the streambank varies with the contractor. Expect to pay between $0.55 to $1.00 per linear foot. These costs are estimated from the IStART project that was installed in the spring of 1995. The cost varies with the ratio of horizontal to vertical slope that is desired. If a 1:1 ratio will suffice, then less soil has to be moved and less time will be spent with the backhoe reducing the cost.
Costs for Eastern redcedar Tree Revetments
Eastern redcedar (Juniperus virginiana) trees can be used to reduce the erosive power of stream flow along the toe of streambanks. Eastern redcedar trees are preferred because they have a high leaf surface area that is retained for long period of time after harvest. Some consider Eastern redcedar to be an undesirable species throughout much of the Midwest, and, therefore, it can usually be obtained for free.
Eastern redcedar trees are installed along the toe of the streambank, which is susceptible to scour. If the toe of the streambank is not stable, then any bank work done above it has a high possibility of being undercut and eroding into the channel. Willow posts and metal fence “T-posts” are a small selection of the many methods to secure the trees to the toe of the streambank. The Eastern redcedar trees are anchored to the willow posts or T-posts using wire or twine, making sure to have the butts of the trees pointed upstream. Open grown Eastern redcedars, at least 10 ft in height, are best suited to this practice because they have a full complement of branches and needles along the main stem of the tree.
It is imperative to get the Eastern redcedar anchored into the bottom of the streambed right along the toe of the bank to insure that undercutting does not occur. It is also very important to tie the Eastern redcedar into the streambank at the upstream end of the bioengineering system. If this is not done high velocity streamflow will get behind the installed Eastern redcedar and undercut the bank. To decrease the possibility of the stream cutting behind the Eastern redcedar trees, it is necessary to lengthen the upstream end of the Eastern redcedar tree installation as well as the rest of the streambank bioengineering system past the point of streambank failure by 10 to 15 feet. The same precautions should be taken on the downstream end of the bioengineering system, although given time and budget limits the upstream end is more critical. Once the Eastern redcedar trees have been installed, it is good to install one row of willow posts within the trees at a spacing of 2 to 3 ft between willows.
Costs for this portion of a streambank bioengineering system are dependent on distance, method of hauling, and size of the trees. Before selecting this component for a streambank bioengineering project, be sure that a source is located five miles or less from the project site. Labor can constitute between 50% and 60% of the cost of an Eastern redcedar tree streambank bioengineering component based on costs incurred in the IStART projects.
Fascines can be an important component of a streambank bioengineering system. Fascines are long bundles of willow tops, the small unused sections of the thinner stems of the willow trees that were harvested for posts and cuttings. Fascines are placed into a shallow trench at or above the normal flow stream depth. The purpose of using fascines is to produce many willow shoots and roots in the area where the fascine is placed. Within one month after placement of a fascine, willow shoots emerge producing a carpet of grass-like willow sprouts that root into the streambank and stabilize the soil and anchor the geotextile.
Construction of fascines is accomplished by grouping the dormant willow tops into a one-foot diameter by twenty foot long bundle. Twine is wrapped around the bundle to aid in stability when moving the fascines into the streambank bioengineering system. A shallow trench, into which the fascine is placed, is dug in the bank just above normal streamflow. To ensure that the fascine does not move during high stream flows, just after planting, willow posts or wooden stakes are driven into the fascine at 4 ft intervals. Soil is spread over the fascines to reduce the possibility of drying out. Care must be taken to cover the fascine lightly with soil. Growth will not occur if too thick a layer of soil is used. At least the top few twigs of the bundle should have access to daylight.
Fascine costs are dominated by the cost of labor, as calculated from the installation of a fascine in the IStART project. Thirty to fifty percent of the cost of installing a fascine can be accounted by the cost of labor. The price for willow can also greatly affect the cost per linear foot of a fascine component in a streambank bioengineering system. The willow used in a project like this can come from the tops of the willows harvested for the posts or cuttings that are usually used in conjunction with the fascine. If the tops from willows harvested for posts and cuttings are utilized, then the cost of the fascines are greatly reduced.
Costs for Installing Willow Posts and Cuttings
Willow posts and cuttings are the most common components of a streambank bioengineering system. Willow posts and cuttings are simple to prepare and install. They are used because they root easily from hardwood cuttings. Groves of willow can be found within five miles of a project site along nearly every waterway, though not all may have the size of trees needed for longer and larger posts. Collection of the willow occurs during the dormant season, late fall until the middle of March depending on the location of the project and the weather. Once the willow has been harvested, it should be stored in the dark at temperatures of 40° F or lower and kept moist. If the stated conditions for storage are met, the willow material will last well into the spring planting season.
Willow trees can be easily prepared for installation. The trees are cut into three different types of planting material depending on the project. There are posts, cuttings and material for fascines. Posts are larger in diameter, greater than two inches in diameter and four feet or more in length. Posts may be up to six inches in diameter and 8-10 ft in length. Cuttings are smaller than two inches in diameter and up to four feet in length. Cuttings and posts should be free of all branches before planting. If the posts and cuttings are to be stored for three or more weeks before planting they are best left in whole tree lengths or the longest length that can be transported. This will reduce any drying of the stems that might occur during long periods of storage. Trees can be cut to the proper length just before installation. Before a post or cutting can be planted, they should be soaked in water for up to twenty-four hours. The posts should be sharpened on the end that will be driven into the streambank. Once the planting material has been soaked and sharpened it is ready for planting. Willow posts and stakes and cuttings should be planted with the correct end up so that rooting and sprouting can occur. In other words, the willow will not grow if planted upside down.
Posts are planted in the streambed and the toe of the streambank because they are stronger and longer. They should be planted as deep as needed to reach a solid streambed material that will not be influenced by the turbulence of streamflow. The deeper the post is planted, the less chance the post will be removed by flood waters. The rows of posts planted in the streambed will probably only live for two to three years. During this time they serve the important purpose of slowing the water until the posts at the toe of the bank have become established.
Installing the posts is achieved by one of the following methods: pounding the post with a sledge hammer, drilling holes with an auger and placing the posts into the holes, or punching a hole into the streambank with a metal probe and then placing the post into the hole. The auger and metal probe in the last two methods are usually mounted on a backhoe. Whatever method is used, be sure the post is planted deep enough so that it will not be removed by flood waters and the buds are pointed up. Usually two rows of posts are planted in the streambed with one or two more planted in the toe of the strreambank. These plantings are on a 3 x 3 ft spacing.
Willow cuttings are planted into the streambank above the posts all the way up to the top of the streambank on a 3 x 3 ft spacing. The cuttings are inserted into the streambank as far as possible, at least two feet or more deep. Only two or three buds should to be above ground for the cutting to survive. The deeper the material, post or cutting, is inserted the better.
The cost of labor constitutes the majority of the cost per linear foot when collecting, constructing, or installing willow posts or cuttings. If willow material can be found that is free of charge, the cost per linear foot can be reduced considerably.
The following tables give numerous possible combinations of willow posts and cuttings. An example of how to calculate the cost of a willow post and cutting system follows in the last table.
The following is an example to show how to add costs for three rows of posts and four rows of cuttings, if they are planted together on the same day and the willow is obtained free of charge. Costs are presented on a per-linear-foot of streambank.
Collection and Installation
* three rows of posts: $2.26
* four rows of cuttings: $1.53
Cost of willow material
* three rows of posts: $0.44
* four rows of cuttings: $0.58
Total for three rows of posts: $2.70
Total for four rows of cuttings: $2.11
Total per linear foot for three rows of posts and three rows of cuttings: $4.81
Rock Rip Rap
Rock rip rap is used in streambank bioengineering systems to stabilize the toe of the streambank in situations where Eastern redcedar is not available or where a stronger toe control system is desired. The rock is hauled to the site and a backhoe places the rocks into the stream. The rock should be placed in the streambed at the base of the toe of the bank and extend two to three feet up the toe of the slope above normal stream flow levels. In some cases it may be necessary to dig a trench in the streambed to assure that the rock makes contact with solid streambed material. It is also important to assure that the upstream and downstream ends of the rip rap are tied into the streambank so that streamflow cannot scour behind the rip rap. The size of the rock should be large enough so that the rock is not moved during flood flow. There are many charts and tables that will determine the size of the rock that should be used for a certain sizes of streams.
The cost per linear foot is most influenced by the cost to haul the material to the site. A local source of rock should be located before using this component of a streambank bioengineering system. Hauling the rock for the system installed in Story County accounted for 30% of the cost per linear foot.
Maple Bundle Costs
Silver maple (Acer saccharinum) is used to create bundles that act to armor vertical streambanks and allow for planting of willow posts and cuttings. These bundles are composed of dead trees that are not expected to sprout, but provide temporary protection until they decompose or the associated willow plantings have become established. The bundles have gaps that allow willow posts and cuttings to be planted right through the bundles and into the streambed and streambank. Armoring the streambank acts to reduce the stream velocity of water that directly hits the streambank. If the velocity is reduced, then there is less erosive energy that could damage the streambank.
Silver maples were used in constructing bundles in the IStART projects because they were available and of the correct size (three to six inches in diameter and 15 to 20 feet long), but any multi-stemmed trees would work. The key is getting large amounts of material with as little effort and cost as possible. Multi-stemmed trees yield large amounts of material with little work. Once the trees have been cut, bundles of five to seven trees are wired together with electric fence one-fourth gage or similar wire, every five to seven feet. Be sure the wire is tight so that when in the stream flood water will not tear the bundles apart.
To install the bundles, metal T-posts or willow posts must be driven into the streambank about every five feet from upstream of the eroding streambank to down stream of the eroding streambank to be protected. The bundles are placed next to the posts and wired to them. The posts can also be driven through the bundles, instead of next to them to increase the stability of the bundles against flood flows. The first bundle row must be at the toe of the streambank. The bundles should cover one-third to one-half of the streambank to ensure streambank stability. The tighter the bundles are placed next to the streambank, the lower the risk of scouring under and around the bundles. Bundles should be used in conjunction with installing willow posts and cuttings.
The cost of using tree bundles is expensive on a per-linear-foot basis. Costs are high because this form of streambank bioengineering is labor intensive. One-half of the cost to install a bundle system is spent on labor, based upon costs incurred on the bundle systems installed in the IStART projects. Constructing, installing, and positioning the bundles is difficult because of the size and awkwardness of the material.
Establishment of the wetland cost approximately $2800. Most of this cost ($2400) was associated with excavation charges. As mentioned, due to the presence of some alluvial sands at the chosen site, several truckloads of clay were required to seal the bottom of the wetland. In many areas this may not be required and construction cost would be substantially reduced.
Objective 6 – Develop appropriate technology transfer materials and activities for farmers, policy-makers, farm groups, and others.
Another objective of this project has been the encouragement of the adoption of the riparian management system through a number of technology transfer activities. We have been very active in trying to get the story told to as many audiences as possible. A complete list of technical and news articles published, presentations, workshops, conferences and other means of educating diverse audiences on project findings is included below under Section B – Dissemination of Findings. Additional technology transfer activities include:
Educational brochures. A integrated series of educational brochures is being developed to be distributed through the ISU Cooperative Extension Service and USDA-Forest Service – Northeast State and Private Forestry. These brochures will also be distributed at all field days and presentations. The series is entitled “Stewards of our Streams” and will include the following publications:
Stewards of our Streams: Riparian Buffer Systems. Pm-1626a
Stewards of our Streams: Buffer Strip Design, Establishment, and Maintenance.
Stewards of our Streams: Streambank Stabilization. Pm-1626c
Stewards of our Streams: Restoring Wetland Buffer
Stewards of our Streams: Financing Riparian Restoration Projects. Pm-1626e
The initial brochure, Stewards of our Streams: Riparian Buffer Systems is an introduction to the series and gives an overview of riparian zone function and management. This twelve page, four-color brochure is complete, with 5,000 copies printed. A copy has been included in Appendix IV.
The subsequent two-color brochures will provide technical detail on each of the specific topics related to riparian zone management and restoration. The second brochure in the series, Stewards of our Streams: Buffer Strip Design, Establishment, and Maintenance, is in the final production stages. The final draft of this publication is currently being reviewed by the Iowa Department of Natural Resources and the USEPA Region 7 Office. A copy of the final draft of this publication is included in Appendix IV.
A preliminary draft of the third publication in the series, Stewards of our Streams: Streambank Stabilization, is complete. This publication is being co-sponsored by the Leopold Center for Sustainable Agriculture.
Prior to the development of the Stewards of our Streams series, preliminary versions of the educational brochures were distributed to all field day attendees, made available at all presentations, and mailed upon request. These preliminary educational brochures were entitled “Your guide on how to make a riparian buffer strip” and “Design and establishment of a multi-species riparian buffer strip.” We estimate that over 5000 copies of these materials have been distributed.
Field Days. We estimate that over 800 individuals have visited the project site during the last two years as part of the more than 30 formal tours that have been hosted. Two of these tours have been field days organized for local landowners and citizens. One field day, jointly sponsored by the Leopold Center for Sustainable Agriculture, Iowa State University Extension, and the USDA-NRCS offices of four Central Iowa counties, was held on August 30, 1994 and was attended by nearly 80 people. Attitudes and impressions of field day participants were assessed through the means of a follow-up questionnaire mailed to all attendees and are summarized in Farmer Evaluations/Testimonials [not available online]. A second field day, in the form of a streamside tour and dinner for landowners and farmer/operators in the Bear Creek watershed, was held on September 7, 1995. Copies of the invitation notices for these two field days are included in Appendix IV.
Among others, the project site was also visited by the State of Iowa Natural Resources Commission, the State of Iowa Soil Conservation Commission, 45 farmers attending a crop production workshop sponsored by Iowa State Cooperative Extension Service, 60 people attending the Leopold Center for Sustainable Agriculture Annual Conference, 50 conservation professionals attending the Annual Meeting of the Soil and Water Conservation Society, and 34 individuals attending the National Conference of Landscape Architecture Educators. A complete list of tours, field days and educational visits to research sites is included under Publications/Outreach.
Self-guided Trail. A self-guided trail has been established at the Risdal research site, which includes stops illustrating the buffer strip, steambank stabilization technologies, and the wetland. In addition, the trail has stops at a two-year old buffer strip immediately upstream from the Risdal site (on the Strum farm) and at small prairie restoration. A copy of the self-guided trail brochure is included in Appendix IV. An information kiosk with a 4′ by 8′ display area is used to provide further information to individuals touring the site. This kiosk can also be used to present information specific to each tour being hosted.
Video and Slide Set Production. A 70-slide set has been developed and is used extensively by project personnel. This slide set has been duplicated and has been sent to numerous persons or groups around the country for use. In addition, plans for the next year include the development of a 15-20 minute video. The video will assess present conditions of mismanaged riparian zones, describe how an effective buffer strip functions, show before-and-after footage of successful MRBS (from the Bear Creek site), and describe how to construct a MRBS management system. This video will be used by extension specialists, coop agronomists, FFA and high school teachers, and others to make meaningful presentations to a wide variety of audiences. This video would be a part of displays at major meetings such as the 1996 Farm Progress Show to be held in Amana, IA and the Iowa State Fair. This video will be supplemented with the various bulletins produced in the objectives described above. These initiatives are also being supported by the Agriculture in Concert With the Environment Program through Project Number LWF 62-016-03028.
While the project has taken about eight acres of land out of grazing or row-crop production, Mr. Risdal, the landowner, feels that the positive benefits of the altered land management have compensated for this loss. One of his major objectives in cooperating with the project was to establish habitat for wildlife, including improving the in-stream environment for fish. He has seen a dramatic increase in wildlife (see objective 4) along the buffer strip and around the constructed wetland. In the severe cold weather and deep snow of late January 1996 he saw over 40 pheasants using the switchgrass and shrubs of the buffer strip. He views this as very positive and likes to spend time along the buffer strip walking and fishing with his grandson.
Mr. Risdal likes the results enough that he has planted an additional 3/4 acre to conifers, which he hopes to sell for Christmas trees. He is also reestablishing a small prairie with over 20 forbs and native grasses on a 0.2 ha (1/2 ac) site in a bend of the buffer strip. He frequently asks us when we are going to finish planting the rest of the control plots (plots left in pasture grass) to trees, shrubs, and switchgrass. He has closed several access roads, requiring him to take longer routes to his fields, so that the areas can be planted to more native plants. He sees this as ideal bird habitat and is getting an increasing number of requests for permission to hunt from friends and neighbors. He sees this project as a model for improving the quality of life in the rural agricultural landscape.
Because of the enthusiastic support for the project by the landowner, the upstream landowner, Mr. Lon Strum, asked us to establish a 1.6 km (1 mi) long demonstration site on his farm.
Establishment of the MRBS on this site was completed in 1994. This year, Mr. Jordan Larson, a landowner two farms upstream from the Strum farm, has also planted a 1 km (0.6 mi) long MRBS on both sides of Bear Creek as it runs through his land. In each of these cases the major objective of the landowners and farmers were to re-establish wildlife habitat along the creek even at the cost of losing some productive crop ground.
The components of the RiMS act as a permanent corridor within the cropping system matrix of the agricultural landscape. As such, the corridor provides wildlife habitat, is beginning to improve the in-stream environment, reduces winds on the downwind landscape, provides habitat for beneficial insects and birds that prey on several major corn and soybean pests, and sequesters carbon that would otherwise contribute to global warming. A proposal to study corn insect dynamics around the buffer strip has been submitted by a team of entomologists.
This system addresses a major recommendation made by the National Research Council (Soil and Water Quality: An Agenda for Agriculture, National Academy Press, 1993) that the agricultural landscape must be made more resistant to erosion and runoff by increasing the use of field and landscape buffer zones. These buffer zones improve soil quality, which allows them to intercept and immobilize nonpoint source pollutants generated in adjacent row-cropped fields.
Estimates of reduced sediment entering into the stream because of the MRBS can be made from visual estimates of sediment movement. These visual estimates suggest that at least 90 percent of the sediment leaving the cropland in surface runoff is being trapped by the buffer strip. If a conservative estimate of 10 tons of soil erosion per acre is used (using RUSLE) from approximately 30 acres that slope directly toward the creek along the farm, then the buffer strip is potentially keeping 270 tons of soil from entering the creek from this farm each year.
Similarly, inputs of nitrate and atrazine from the vadose zone and shallow groundwater to the creek have been reduced by 80-90% each year by the buffer strip. The wetland is also substantially reducing chemical loading from the agricultural drainage tile that it intercepts These reductions in chemical loading not only benefit the in-stream organisms but reduce the cost of removal by communities downstream, which may use the water for domestic use. For example, the city of Des Moines, Iowa, has had to install a nitrate removal system in its drinking water purification system because it uses water from the Raccoon River, which drains similar agricultural landscapes.
The soil bioengineering system that has been installed along about 400 ft of bank has greatly reduced bank collapse. Prior to installation of the willow post system, a 16 foot length of bank, 6 feet high, collapsed into the creek in a three year period. This amounted to about 25,600 ft of soil. Assuming a bulk density of 1.5 this is equivalent to about 20 tons of soil. Since the willow post system has been installed, less than one additional foot of bank has been lost and most of that has slumped in place. Additional sediment from high flow events is also being trapped in the vegetated stream banks. Similar kinds of reductions can be seen in the willow post/silver maple revetment system and in the willow post/geotextile/rock rip-rap system that were installed. In the latter system the grass and natural geotextile have totally eliminated production of sediment from the streambank. This was accomplished in one growing season.
This riparian zone integrated management system protects the ecosystem by improving soil and water quality. It also improves wildlife habitat and local microclimates, and improves the quality of life for rural residents, which will help to foster much needed rural development.
While only one model of the riparian zone management system is being studied at this site, the system has many variants that will benefit almost any riparian zone in the agricultural landscape. Our work has been expanded and now protects about 2.2 stream miles along Bear Creek. As a result of this work, many additional miles of similar systems are being installed by professionals and landowners throughout Iowa and the Midwest.
1. The system being studied on the Risdal farm is of one basic design, namely five rows of trees, two rows of shrubs, and a zone of switchgrass all in a 20 m (66 ft) wide strip. This system was selected because of the desire to fit cost-share programs that were available to landowners. While we feel this system is of adequate width to trap sediment from surface runoff and intercept and immobilize agricultural chemicals in the surface and subsurface water, we also believe that other plant configurations and other widths of strips can be effective.
Additional systems should be tested that vary the plant combinations. Examples of these include:
* More rows of trees, with those furthest away from the stream being slower growing, high quality hardwoods such as oak and walnut that can provide more diversified income to the landowner;
* No trees and more shrubs, in situations where there is concern for trees shading the stream, blocking views, providing fewer perches for raptors, or where the landowner simply doesn’t want trees;
* Wider zones of grass and other mixtures of native grasses and forbs;
* Zones of grass adjacent to the creek with trees and/or shrubs placed further back away from the stream. We feel a minimum of 7 m (20 ft) of native grass is needed at the interface of the buffer strip with the row-crop field to act as a sediment trap for overland flow.
2. Different MRBS widths should be tested with the design based on slope and upslope cropping practices. We hypothesize that a minimum of 15.2 m (50 ft) is needed to intercept and immobilize the chemicals moving in the surface and subsurface water. However, a minimum of only 9 m (30 ft) may be needed to trap any surface runoff from cropped fields of less than 5% slope or if no-till cultivation is used.
3. The MRBS model must be demonstrated within grazing systems. The technology of installing grazing systems on Midwestern streams is available and consists primarily of fencing the livestock out of the stream, providing controlled crossings, and providing alternative watering systems. A feature that is missing from most of these demonstrations is how to manage the area between the fence and the stream, including the streambank. By removing cattle pressure, grasses may be invaded by noxious weeds. Work must be done to develop native grass, shrub and tree mixtures that will help to provide a stable plant community with attractive features. In addition, streambank bioengineering techniques must also become an integral part of the grazing systems.
4. Basic and applied research is needed to determine the fate of removed chemicals. We must determine how much of the removed nitrogen, for example, is being sequestered in the various plant components, and how much is denitrified by microbial activity within the buffer strip. Similar work is needed for pesticides such as atrazine and nutrients such as phosphorus. While some of these studies can be made in isolated columns in laboratories, field research has to be conducted to develop a nutrient and pesticide budget for riparian zone management systems.
5. Work is needed to quantify changes in soil quality over time as a result of the establishment of a MRBS. To accomplish this, above- and below-ground organic matter dynamics must be studied and changes documented in infiltration rates and hydraulic conductivity of the soil profiles.
6. The sizing of wetlands to treat chemical loading from specific field sizes must be verified. The model that is presently being used is the result of experimental work under very controlled conditions. The results of this work must be verified at the landscape level. The work with our constructed wetland is an early field example based on the experimental models.
7. Proper placement of wetlands in the agricultural landscape must be identified. Although there are many small tiles draining individual fields, it is often the large collector tiles that provide the measurable inputs of some agricultural chemicals to the stream. Models for the design and placement of these larger wetlands must be developed and demonstrations must be installed to test their relative effectiveness at improving water quality.
8. Soil bioengineering models must be further developed. At present, most of the work has been based on empirical observations and trial-and-error in real life situations. These must be continued, but well monitored demonstrations must be installed to determine the size of cuttings, planting density, species success, and actual sediment trapping abilities of these systems. Systems of various “guaranteed” stability must be designed and tested on streams larger than Bear Creek. Fourth and fifth order streams must be found where larger willow and other plant material are used, in conjunction with hard engineering methods, to stabilize the banks. Additional species of shrubs must be identified that can be used in place of willow, especially where beaver may become a nuisance to the system.
9. Willow posts and stakes can be used to stop gully development. Designs must be developed that will fit various sizes and depths of gullies found in varying soil types.
10. We believe the riparian zone management system that we are developing is adaptable to the urban environment, but research is needed to identify the different inputs and problems found in that environment.
11. There is a need to conduct research on the benefits and costs of these systems, especially on the numerous intangible benefits of the system. Research also is needed on the perceptions of landowners to the need for riparian zone management systems and their willingness to adopt such systems. We strongly believe that these systems should be voluntarily installed in the landscape rather than mandated. The problem with many mandates is that their specifications are very restrictive and often are not flexible enough to fit the broad range of conditions found in the landscape. We must impress on farmers that if riparian zone management systems are not voluntarily adopted, the chance is great that the urban population of the country will support mandated systems. Focus groups and one-on-one discussions with farmers and landowners are needed to develop a broad-based model for voluntary adoption.
12. Watershed level studies are needed to assess the amount of land that would actually be taken out of row-crop or grazing production with the installation of a riparian zone management system. A 66 ft wide system, on both sides of a stream, encompasses 16 acres of land in a mile length of stream. It is doubtful that this much land is taken out of row-crop production because of meanders and crop loss from flood events that occur in more than two or three years out of every five. These studies also should include estimates of the reduction in sediment and chemical loading to the stream if vulnerable riparian areas were managed by the model system. Estimates should include the percentage reduction that would occur with various widths of buffers and various numbers of soil bioengineering systems applied. These kinds of information are needed for policy makers who are looking for the positive impacts of cost-share programs, etc.
Evaluation of the costs of establishing and maintaining the three riparian management systems being demonstrated has been a specific objective of this project. Thus, a summary and analysis of financial costs, returns, and risks of adopting MRBS technologies are included under Objective 5 within Results and Discussion/Milestones.
Changes in Practice
The adoption of the riparian zone management system has begun to gain momentum. The model has been subscribed to by the USDA-Forest Service/USDA-NRCS National Agroforestry Center and the National Arbor Day Foundation. IStART has become partners with scientists at the National Agroforestry Center and at the University of Nebraska to adapt riparian management models to the Midwestern and Great Plains regions. Members of IStART took part in helping draft the National Resource Conservation Service’s Forest Buffer technical guidelines and will be working with the State of Iowa of the USDA-NRCS to adapt those guidelines to the state.
Locally the practice has been adopted by Mr. Lon Strum on the farm adjacent to the Risdal project site. On this farm, an additional 1.6 km (1 mi) of Bear Creek was planted to the buffer strip model during 1994, several hundred feet of stream bank soil bioengineering practices were installed in 1995, and two wetlands will be constructed in 1996. In 1995, we also established another 1 km (0.6 mi) of riparian management system on the Jordan Larson farm, two farms upstream from the Strum farm.
The practice is being demonstrated in the Loess Hills State Forest in western Iowa where about 0.8 km (0.5 mi) of stream received a buffer strip in 1994.
Mr. Robert German installed about 0.8 km (0.5 mi) of the buffer strip on a creek running into the Raccoon River on his land in Dallas County, IA.
We are working closely with the District Conservationists and their staffs in the Beed’s Lake watershed, near Hampton, IA, the Pine Creek watershed near Eldora, IA, and the Storm Lake watershed near Storm Lake, IA.
In the Storm Lake watershed we have installed a 1 km (0.6 mi) MRBS demonstration along Powell Creek and will install another 1.6 km (1 mi) further downstream in the coming year. In addition, a MRBS will be established along a 1.2 km (0.75 mi) reach of Episcopal Creek, which also feeds Storm Lake.
We are working with USDA-NRCS, IDNR and USFWS to establish a riparian management system on the Volga River in northeast Iowa.
We are working with the Iowa Natural Heritage Foundation and the Nature Conservancy in designing riparian management systems on private farms as part of the Raccoon River Watershed Project.
We are working closely with Hertz Farm Management Corporation to stabilize streambanks on one of the farms they manage near Garden City, IA.
All of our demonstrations are located on private farms. We have reviewed numerous other plans for farmers and professionals who are installing buffer strips and streambank bioengineering systems on their farms. We have provided review and discussion to numerous planners from the Dakotas to Wisconsin.
In addition to the “on the ground” work that is being done, we have sent packets of information to 51 persons.
We believe that at least a portion of these professionals are recommending buffer strip systems that include parts of the RiMS model. In discussions with professionals from Minnesota, North and South Dakota, Nebraska, Missouri, and Kansas, we believe that this model is being used in total or in modified forms. In all of our discussions and presentations we stress that there are many variants to this model that will fit the numerous landscapes that are encountered across the mid-section of the country.
Our general recommendations are that farmers should not cultivate row crops within 9-30 m (30-100 ft) of a stream channel. This recommendation should be applied to ephemeral, intermittent, and perennial channels of all orders of streams. In place of cultivation, a permanent vegetation community should be established that is similar to the model that IStART is developing. This model addresses not only the need for multi-species buffer strips, but also the need for streambank bioengineering and constructed wetlands for agricultural drainage tiles. Where grazing is being done in the riparian zone, livestock should be excluded from the streambanks and channel, except under very controlled conditions. The operational recommendations for establishment of the riparian management system are included in the extension bulletin series entitled Stewards of Our Streams which is described under Objective 6 in the report.
Educational & Outreach Activities
The development of appropriate technology transfer materials and activities for farmers, policy-makers, farm groups, and others has been one of the explicit objectives of this project. Progress to date is briefly summarized above under Objective 6 of Results and Discussion/Milestones.
Isenhart, T.M, R.C. Schultz, and J.P. Colletti. 1996. Riparian management for water quality: the Bear Creek example. Pages 5-23 – 5-30 in Proceedings of Agriculture and Environment: Building Local Partnerships Conference. Ames, IA. January, 1996.
Schultz, R.C., J.P. Colletti and R.R. Faltonson. 1995. Agroforestry opportunities for the United States of America. Agroforestry Systems 31:117-132.
Schultz, R.C., J.P. Colletti, T.M. Isenhart, W.W. Simpkins, C.W. Mize and M.L. Thompson. 1995. Design and placement of a multi-species riparian buffer strip system. Agroforestry Systems 29:201-226.
Colletti, J.P., R.C. Schultz, R.R. Faltonson and T.M. Isenhart. 1995. Creating a buffer. Iowa Conservationist. July/August, 1995.
Schultz, R.C. and T.M. Isenhart. 1995.
Streamside buffers to protect water quality. Pages 193-200 in Proceedings of the 1995 Integrated Crop Management Conference. Ames, IA. November, 1995.
Isenhart, T.M., R.C. Schultz, J.P. Colletti, and C.A. Rodrigues. 1995. Design, function, and management of integrated riparian management systems. Pages 93-102 in Proceedings of the National Symposium on Using Ecological Restoration to Meet Clean Water Act Goals. USEPA. Chicago, IL. March, 1995.
Schultz, R.C., J.P. Colletti, T.M. Isenhart, W.W. Simpkins, C.A. Rodrigues, P. Wray, M.L. Thompson, and J. Pease. 1995. Riparian buffer strip systems that improve water quality. Pages 235-238 in Proceedings of the Clean Water-Clean Environment-21st Century Conference. Kansas City, MO. March, 1995.
Isenhart, T.M, R.C. Schultz, and J.P. Colletti. 1995. Design, function, and management of multi-species, riparian buffer strip systems. Pages 4-5 in Proceedings of the Watershed Management Workshop for the James, Vermillion, and Big Sioux Rivers. Huron, SD. February, 1995.
Schultz, R.C., T.M. Isenhart and J.P. Colletti. 1995. Riparian buffer systems in crop and rangelands. Pages 13-27 in Agroforestry and Sustainable Systems: Symposium Proceedings. USDA-Forest Service General Technical Report RM-GTR-261.
Schultz, R.C., J.P. Colletti, W.W. Simpkins, C.W. Mize, and M.L. Thompson. 1994. Design and placement of a multi-species riparian buffer strip system. Pages 109-120 in Schultz, R.C. and J.P. Colletti (eds) Proceedings of the Third North American Agroforestry Conference. Ames, IA. August, 1993.
Schultz, R.C. 1994. Iowa State Evaluates Buffer Best Management Practices. USEPA Nonpoint Source News-Notes. July/August 1994.
Schultz, R.C., J.P. Colletti, C.W. Mize, W.W. Simpkins, and M.L. Thompson. 1994. Developing a riparian buffer strip agroforestry system. Abstracts of Society of Range Management Annual Meeting. Colorado Springs, CO. Feb. 13-18, 1994.
Schultz, R.C., J.P. Colletti, W.W. Simpkins, C.W. Mize, and M.L. Thompson. 1994. Water Quality Benefits of Agroforestry – Constructed Multi-species Riparian Buffer Strips. Pages 14-35 in Proceedings of the Minnesota Agroforestry Conference: “Working Trees – Farming in the 1990’s.” Owatonna, MN. March 3, 1994.
Articles in preparation
Schultz, R.C. and T.M. Isenhart. Agricultural Watershed Management Research: Bear Creek , Iowa. Chapter 15 in J.E. Williams, (ed.) Watershed Restoration: Principles and Practices. American Fisheries Society.
Isenhart, T.M. and R.C. Schultz. Integrated riparian management systems to protect water quality. To be included in Proceedings of the Workshop on Filter and Buffer Strip Research. USDA-ARS. Temple, TX. September, 1995.
Colletti, J.P., C.J. Ball and R.C. Schultz. Benefits and costs from stream protection using an integrated riparian management system. To be included in the Proceedings of the 4th North American Agroforestry Conference. Boise, ID. August, 1995.
Schultz, R.C., T.M. Isenhart, J.P. Colletti, and C.A. Rodrigues. Integrated riparian management in row-crop ecosystems. To be included in the Proceedings of the 4th North American Agroforestry Conference. Boise, ID. August, 1995.
Schultz, R.C., J.P. Colletti, T.M. Isenhart, R.R. Faltonson, and C.A. Rodrigues. 1996. Energy crops: an opportunity for restoring riparian zone functions. To be included in the Proceedings of the Conference – Environmental Effects of Biomass Crop Production. Oak Ridge, TN. August 7-8, 1995.
Manuscripts to be submitted to peer-reviewed journals
1) Overall description of integrated riparian management system function.
2) Results of water quality investigations quantifying the effectiveness of a constructed multi-species riparian buffer strip to act as a sink for nonpoint source pollutants.
3) Results of five years of overall watershed water quality monitoring.
4) Soil quality changes after five growing seasons.
Newspaper and magazine articles:
December, 1995 Restoring Iowa’s Streambanks. Trees Forever News.
Fall, 1995 Corridors for water and wildlife. Pheasants Forever: The Journal of Upland Game Conservation.
Oct. 25, 1995 Roland buffer strip project attracts international attention. The Story City Herald.
Spring, 1995. Better care for creeks. The Furrow, John Deere Inc. Volume 100, Issue 4.
February, 1995 Streambank buffer strips. Wallaces Farmer.
Jan. 1, 1995 Streamside filter strips work. Des Moines Register.
Sep. 27, 1994 Storm Lake studying tree-filter project. Iowa State University Daily.
Sep. 17, 1994 Buffer strips: effective pollution control. Ames Daily Tribune.
Sep. 14, 1994 Bear Creek: plantings along creek slow runoff from fields. AGRI-TIMES.
Dec. 1993 Strips filter runoff: grass, trees reduce contamination. Farm Journal
Presentations at workshops and conferences and other events:
Streamside buffers to protect water quality. R.C. Schultz and T.M. Isenhart. 1995.. Invited presentation by R.C. Schultz at the 1995 Integrated Crop Management Conference. Ames, IA. November 30, 1995. (~80 attendees)
Use of buffer strips for protecting water quality. R.C. Schultz. Presentation to the Vocational Agriculture Class at Roland Story High School in Story City, Iowa. November 22, 1995 (~20 students)
A multi-species riparian buffer strip system for reducing nonpoint source pollution. R.C. Schultz, J.P. Colletti, T.M. Isenhart, W.W. Simpkins, C.W. Mize, M.L. Thompson, and J. Pease. Poster Presentation at the 87th Annual Meeting of the American Society of Agronomy. St. Louis, MO. October 29-November 3, 1995.
Prevention of nitrate contamination of surface and ground waters: the role of landscape buffers. T.M. Isenhart. Invited presentation to the Iowa State Department of Agronomy Soil Science Seminar. October 4, 1995. (~30 attendees)
Riparian buffer strips – establishment and management. T.M. Isenhart. Invited presentation to the 1995 Iowa Master Woodland Managers Program. Yellow River State Forest, Allamakee, County IA. September 21, 1995. (~35 attendees)
Integrated riparian management systems to protect water quality. T.M. Isenhart. Presentation at the “Workshop on Filter and Buffer Strip Research.” Hosted by the USDA-NRCS Blackland Research Center. Temple, TX. September 13-14, 1995. (~50 attendees)
Benefits and costs from stream protection using an integrated riparian management system. J.P. Colletti. Presentation at the “Workshop on Filter and Buffer Strip Research.” Hosted by the USDA-NRCS Blackland Research Center. Temple, TX. September 13-14, 1995. (~50 attendees)
Riparian zone management and streambank stabilization using soil bioengineering technologies. C.A. Rodrigues. Invited presentation to the “Workshop on Vegetative Approach to Streambank Stabilization” hosted by the USDA-NRCS. August 29, 1995. Marquette, IA. (~30 attendees)
Integrated riparian zone management in the Storm Lake watershed. T.M. Isenhart. Invited presentation to the USDA-NRCS Iowa Special Projects Tour. August 29, 1995. Storm Lake, IA (~12 attendees).
Using biomass crops to provide riparian zone and water quality protection. R.C. Schultz. Invited presentation at the “Environmental Effects of Biomass Crop Production” Conference sponsored by Oak Ridge National Laboratory. Oak Ridge, TN. August 7-8, 1995. (~250 attendees)
Integrated riparian management systems to protect water quality. R.C. Schultz, T.M. Isenhart, J.P. Colletti, W.W. Simpkins, C.A. Rodrigues, and J.R. Thompson. Poster presentation at the Soil and Water Conservation Society 50th Annual Meeting. Des Moines, IA. August 6-9, 1995. (~900 attendees)
Design options for riparian zone management systems. R.C. Schultz, J.P. Colletti, T.M. Isenhart, C.A. Rodrigues, R.R. Faltonson, W.W. Simpkins, and M.L. Thompson. Presentation at the 4th North American Agroforestry Conference. Boise, ID. July 23-26, 1995. (~300 attendees)
Reduction of nitrate and atrazine concentrations by a multi-species buffer strip. C.A. Rodrigues, R.C. Schultz, T.M. Isenhart, J.P. Colletti, W.W. Simpkins, and M.L. Thompson. Presentation at the 4th North American Agroforestry Conference. Boise, ID. July 23-26, 1995. (~300 attendees)
Constructed wetlands and streambank stabilization as components of integrated riparian management systems. T.M. Isenhart, R.C. Schultz, J.P. Colletti, and C.A. Rodrigues. Presentation at the 4th North American Agroforestry Conference. Boise, ID. July 23-26, 1995. (~300 attendees)
Benefits and costs from stream protection using an integrated riparian management system. J.P. Colletti, C.J. Ball, and R.C. Schultz. Presentation at the 4th North American Agroforestry Conference. Boise, ID. July 23-26, 1995. (~300 attendees)
Riparian buffer strip systems that improve water quality. R.C. Schultz, J.P. Colletti, T.M. Isenhart, W.W. Simpkins, C.A. Rodrigues, P. Wray, M.L. Thompson, and J. Pease. Poster presentation at the symposium “Clean Water-Clean Environment-21st Century” sponsored by the USDA. Kansas City, MO. March 6-8, 1995. (~500 attendees)
Agricultural floodplain and stream management. Agroecology Issue Team. Poster presentation at the Leopold Center for Sustainable Agriculture Annual Meeting. Ames, IA. March 3, 1995. (~200 attendees)
Riparian buffer strip systems that improve water quality Poster presentation at the Leopold Center for Sustainable Agriculture Annual Meeting. Ames, IA. March 3, 1995. (~200 attendees)
Function of riparian zones and methods for remediating problems. R.C. Schultz. Invited 1/2 day presentation at EPA Workshop in March 20-23, 1995. (~100 attendees)
Design, Function, and Management of Multi-species Riparian Buffer Strip Systems. T.M. Isenhart. Invited presentation to the symposium on “Using Ecological Restoration to Meet Clean Water Act Goals.” Chicago, IL. March 13-16, 1995. (~250 attendees)
Design and function of riparian buffer strips for midwest streams. R.C. Schultz and T.M. Isenhart. Presentation at the Iowa Department of Natural Resources Fisheries Bureau Statewide Meeting. Guthrie Center, IA. March 1, 1995. (~50 attendees)
The Bear Creek Buffer Strip Management System. T.M. Isenhart. Invited presentation to the “Watershed Management Workshop for the James, Vermillion, and Big Sioux Rivers.” Huron, SD. Feburary 7-8, 1995. (~90 attendees).
The value of riparian buffer strip systems in Iowa. R.C. Schultz. Invited presentation to the Annual Convention of the Iowa Soil and Water Conservation District Commissioners. Ames, IA. January 17, 1995. (~500 attendees)
Root development and soil quality changes under a multi-species riparian buffer strip. R.C. Schultz, J.P. Colletti, M.L. Thompson, T.M. Isenhart, C.A. Rodrigues, and J.R. Thompson. Poster presentation at the Hamilton Soil and Water Conservation District and SCS Conservation Farmer Appreciation Breakfast and Open House. Webster City, IA. December 3, 1994.
Root development and soil quality changes under a multi-species riparian buffer strip. R.C. Schultz, J.P. Colletti, M.L. Thompson, T.M. Isenhart, C.A. Rodrigues, and J.R. Thompson. Poster presentation at the American Society of Agronomy Annual Meeting. Seattle, WA. November 14-17, 1994.
Riparian buffer strip systems for Iowa. R.C. Schultz. Invited break-out session presentation at the Annual Conference of Iowa Agriculture and Home Economics Extension Service. November 15, 1994. (~20 attendees).
Trees for protection of riparian and wetland areas. R.C. Schultz and J.P. Colletti. Invited presentations at “New Reforestation Technologies: SIP Applications” Workshop sponsored by the US Forest Service. Attendees were invited members of Soil Conservation Service, State Department of Natural Resources and other agencies from an eight state region. Halsey, NE. October 11-13, 1994. (~70 attendees)
Water quality functions of wetlands in agricultural landscapes. T.M. Isenhart. Invited presentation to the Fall Meeting of the Iowa Groundwater Association. Des Moines, IA. October, 1994. (~70 attendees)
Design, establishment, and costs of multi-species riparian buffer strip systems. R.C. Schultz, J.P. Colletti, T.M. Isenhart presented a 1/2 day workshop including field trip to the Iowa Department of Natural Resources, Forestry Division Staff, Ames, IA. September 20, 1994. (~30 attendees)
Functions, problems and solutions for riparian zones. R.C. Schultz. Invited presentation during the Des Moines, IA Parks and Recreation Raccoon River Float Trip. September 10, 1994. (~20 attendees).
Agroforestry research. M.S. Schoeneberger and R.C. Schultz, facilitators. Workshop at the symposium “Agroforestry and Sustainable Systems” sponsored by the USDA Forest Service, Center for Semiarid Agroforestry and USDA-SCS. Fort Collins, CO. August 8-10, 1994. (~150 attendees)
Riparian buffer systems in crop and rangeland. R.C. Schultz. Invited presentation at the symposium “Agroforestry and Sustainable Systems” sponsored by the USDA Forest Service, Center for Semiarid Agroforestry and USDA-SCS. Fort Collins, CO. August 8-10, 1994. (~150 attendees)
Design, establishment, and costs of multi-species riparian buffer strip systems. R.C. Schultz presented a 1/2 day workshop including field trip to help a North Dakota consortium of organizations kick off a major riparian project on numerous sites in the Red River watershed. Grand Forks, ND July 26-27, 1994. (~40 attendees)
Design, establishment, and costs of multi-species riparian buffer strip systems. R.C. Schultz and J.P. Colletti. Invited presentation to the annual meeting of Iowa Soil Conservation Service District Conservationists. Springbrook State Park Conference Center, IA. July 21, 1994. (~ 50 attendees).
Workshop to “Develop a Framework for a Coordinated National Agroforestry Program” R.C. Schultz represented riparian zone interests in developing “Agroforestry for Sustainable Development: A National Strategy to Develop and Implement Agroforestry.” Workshop of 19 Agroforestry Leaders in the US held at the Arbor Day Foundation, Nebraska City, NE, June 29-30, 1994. (19 attendees).
Agroforestry opportunities for the United States of America. R.C. Schultz. Invited presentation at International Symposium on “Agroforestry and land use change in industrialized nations” held in Berlin, Germany, May 30 – June 2, 1994. (~150 attendees)
Riparian buffer strip systems for Iowa. R.C. Schultz. Invited presentation to the Hertz Farm Management Corporation Annual Meeting. May 12, 1994. (~45 attendees).
Agroforestry for the temperate zone. R.C. Schultz. Invited presentation to the ISU Agronomy Forum. April 27, 1994. (~25 attendees)
The role of trees in global climate change. R.C. Schultz. Invited presentation to Agronomy 404 – Global Climate Change Class. April 22, 1994. (~45 attendees).
What’s going on along your streambank? R.C. Schultz. Invited presentation to the Buena Vista County Isaac Walton League. Storm Lake, IA. April 20, 1994. (~35 attendees)
Developing a riparian zone management system. R.C. Schultz. Invited presentation to the School of Natural Resources Seminar, University of Missouri, Columbia, MO. April 8, 1994. (~40 attendees)
Riparian zone buffer strip systems for Iowa streams. R.C. Schultz. Invited presentation to Southeast Iowa Woodland Stewardship Workshop in Burlington, IA. Apr. 7, 1994. (~70 attendees)
Riparian zone function and management. R.C. Schultz. Invited presentation to the Animal Ecology Senior Seminar. April 5, 1994. (~35 attendees)
Forages and trees for producing biomass and improving soil and water quality. R.C. Schultz. Invited presentation to the ISU Forages Group. March 22, 1994. (~15 attendees)
What’s going on along your streambank? R.C. Schultz. Invited presentation to the Nevada, IA Rotary Club. March 16, 1994. (~40 attendees)
Water Quality Benefits of Agroforestry – Constructed Multi-species Riparian Buffer Strips. R.C. Schultz. Invited presentation at the Minnesota Agroforestry Conference: “Working Trees – Farming in the 1990’s.” Owatonna, MN. March 3, 1994.
Developing a riparian buffer strip agroforestry system. R.C. Schultz. Invited presentation at the Annual Meeting of the Society for Range Management, Colorado Springs, CO. February 13-18, 1994.
Restoring riparian zones in Northcentral Iowa. R.C. Schultz. Invited presentation to the Iowa State University Department of Botany Seminar. Feb. 11, 1994.
An interdisciplinary approach to riparian zone management. R.C. Schultz. Invited presentation to the 1994 Fish, Forestry, and Wildlife Conference of the Missouri Department of Conservation at the Lake of the Ozarks, MO. February 3, 1994. (~300 attendees)
Developing a riparian buffer strip agroforestry system. R.C. Schultz. Invited presentation at the Annual Meeting of the National Association of Conservation Districts in Phoenix, AZ Feb. 2, 1994.
Developing a multi-species riparian filter strip agroforestry system. R.C. Schultz. Presented at the Society of American Foresters National Convention. Indianapolis, IN. November 7-10, 1993.
Public attitudes and economic values of a riparian buffer strip. J.P. Colletti. Presented at the Society of American Foresters National Convention. Indianapolis, IN. November 7-10, 1993.
Agroforestry poster including the Bear Creek Project at the 1993 Farm Progress Show. Amana, IA. September 28-30, 1993.
Tours, field days and educational visits to research site or other sites:
Nov. 8, 1995 State of Iowa Natural Resources Commission. (~12 attendees)
Oct. 30, 1995 Restored Wetlands Briefing and Tour. Organized by USDA-NRCS, Iowa Department of Agriculture and Land Stewardship, and Iowa Association of Soil and Water District Commissioners. (~40 attendees)
Oct. 23, 1995 Delegation from the Chinese Ministry of Water Resources.
Oct. 13, 1994 R.C. Schultz and T.M. Isenhart invited on-site assessment with Raccoon River Watershed Project on riparian zone options for the watershed. Bagley, IA. (~5 attendees)
Sep. 11, 1995 National Conference of Landscape Architecture Educators.
Sep. 7, 1995 Streamside Tour and Dinner hosted for landowners/operators in the Bear Creek Watershed. (~15 attendees)
Aug. 19, 1995 Pheasants Forever Summer Habitat Workshop “A New Approach to Habitat – Buffer Strips for Wildlife.” (~25 attendees)
Aug. 9, 1995 1995 Soil and Water Conservation Society Annual Meeting Conservation Tour. (~50 attendees)
July 24, 1995 Australian Midwest Grain and Livestock Tour. (~26 attendees)
July 18, 1995 Minnesota Department of Natural Resources, Natural Resources Conservation Service, and Minnesota Soil and Water Conservation District Commissioners. (~40 attendees)
July 6, 1995 State of Iowa Soil Conservation Committee. (~20 attendees)
June 14, 1995 Tour by visiting delegation of water resource professionals from the Republic of Russia. Organized by the Iowa State University Center for Agricultural and Rural Development. (~11 attendees)
June 13, 1995 Minnesota Department of Natural Resources, Natural Resources Conservation Service, and Minnesota Soil and Water Conservation District Commissioners. (~45 attendees)
June 6, 1995 USDA Forest Service from Radnor, PA. (~5 attendees)
May 11, 1995 Forest Stewards Field Day sponsored by Trees Forever. (~25 attendees)
May 5, 1995 Iowa Department of Transportation delegation of bridge design engineers and vegetation management specialists involved in stream stabilization (~10 attendees)
Nov. 29, 1994 Iowa Department of Agriculture and Land Stewardship, Iowa Natural Heritage Foundation, Center for Agriculture Rural Development, ISU, and Soil Conservation Service. Tour to establish a consortium of agencies in Iowa to foster riparian zone management. (~ 15 attendees)
Nov. 17, 1994 Roland-Story Community School District. High School Vocational Agriculture Class. (~ 20 attendees)
Nov. 5, 1994 CSRS NCR-22 working group comprised of researchers involved with small fruit and viticulture. (~25 attendees)
Nov. 3, 1994. Minnesota Department of Natural Resources, USDA Forest Service State and Private Foresters, and Soil Conservation Service. (~20 attendees)
Nov. 3, 1994 Tour by visiting scientist Dr. Zhang Taolin, Head, Research Center for Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences.
Oct. 20, 1994 R.C. Schultz, J.P. Colletti, and T.M. Isenhart invited on-site assessment with Pine Creek Watershed group on riparian zone options for the watershed. Eldora, IA. (~8 attendees)
Sept. 29, 1994 R.C. Schultz, J.P. Colletti, and T.M. Isenhart invited on-site assessment with Storm Lake Watershed group on riparian zone options for the watershed. Storm Lake, IA. (~8 attendees)
Sept. 20, 1994 Iowa Department of Natural Resources. All Forestry Division Staff.(~30 attendees)
Sept. 1, 1994 Storm Lake Watershed Project Managers visited to learn about options for their project at Storm Lake, IA. (~10 attendees)
Aug. 31, 1994 ISU Cooperative Extension Crop Production Workshop – Profitability & The Environment. (~50 attendees)
Aug. 30, 1994 Field Day sponsored by ISU Cooperative Extension, USDA-SCS, Leopold Center for Sustainable Agriculture. (~80 attendees)
Aug. 4, 1994 Tour in coordination with the Leopold Center for Sustainable Agriculture’s 1994 Annual Conference. (~60 attendees)
July 21, 1994 USDA-SCS District Conservationists and Area Resource Conservationists (~25 attendees)
May 9, 1994 Agriculture Research Service Scientists from Tifton, GA (~8 attendees)
May 6, 1994 Mimi Askew, NRCS Landscape Architect.
Apr. 12, 1994 Midwest Soil Conservation Foresters Annual Meeting Tour and slide presentation (~25 attendees)
Oct. 31, 1993 Tour for program review team for Leopold Center for Sustainable Agriculture. (5 attendees)
Sept. 18, 1993 Tri-State Geological Tour (~40 attendees)
Iowa State University classes utilizing site:
Animal Ecology 300 Seminar in Animal Ecology (~10 students)
Forestry 205 Integrated Forestry Laboratory (~35 students)
Forestry 301 Forest Ecology – 3 hour laboratory (~40 students)
Forestry 407 Forest Watershed Management (~30 students).
Forestry 504 Advanced Forest Ecology and Silviculture (~15 students).
Geological and Atmospheric Sciences 511 Hydrogeology (~15 students)
Geological and Atmospheric Sciences 510 Field Methods in Hydrogeology (~12 students)
Landscape Architecture 461 Resource Conservation and Management (~24 students)
Areas needing additional study
1.Other plant configurations of the multi-species buffer strip should be tested. Examples of these include:
* More rows of trees, with those farthest away from the stream being slower growing, high quality hardwoods such as oak and walnut that can provide more diversified income to the landowner;
* No trees and more shrubs in situations where there is concern for trees shading the stream, blocking views, providing fewer perches for raptors, or where the landowner simply doesn’t want trees;
* Wider zones of grass and other mixtures of native grasses and forbs;
* Zones of grass adjacent to the creek with trees and/or shrubs placed farther away from the stream. We feel a minimum of 7 m (20 ft) of native grass is needed at the interface of the buffer strip with the row-crop field to act as a sediment trap for overland flow.
2. Various widths of the MRBS should be tested based on slope and upslope cropping practices. Widths varying from 7 m (20 ft) to over 30 m (100 ft) should be tested on different soils and slopes.
3. Riparian grazing systems conjunction with the MRBS should be studied. Simply removing cattle from these areas may result in the invasion of undesirable plant species. While livestock should be fenced out of the stream, only a narrow corridor needs to be created, allowing the remainder of the riparian zone can be grazed. Work must be done to develop native grass, shrub and/or tree mixtures that will help to provide a stable plant community in the narrow fenced off corridors. In addition, streambank bioengineering techniques must become an integral part of the grazing systems. Studies should be conducted in the Midwest on allowing rotational grazing of the entire riparian zone to determine if proper rotations could minimize sediment production from impacted streambanks.
4. Basic and applied research is needed to determine the fate of removed chemicals. We must determine how much of the removed nitrogen, for example, is being sequestered in the various plant components and how much is denitrified by microbial activity within the buffer strip. Similar work is needed for pesticides such as atrazine and nutrients such as phosphorus. While some of these studies can be made in isolated columns in laboratories, field research has to be conducted to develop a nutrient and pesticide budget for riparian zone management systems. This work must lead to models that can predict reductions that can be gained from various configurations of RiMS in the wide variety of regions found in the Midwest and the Great Plains.
5. Work is needed to quantify the changes in soil quality that can be expected over time as a result of the establishment of a riparian integrated management system. Once again models must be developed that predict the changes in the rate of infiltration following establishment of RiMS.
6. Proper sizing and placement of wetlands in the agricultural landscape must be identified. Although there are many small tiles draining individual fields, it is often the large collector tiles that provide the measurable inputs of some agricultural chemicals to the stream. Models for the design and placement of these larger wetlands must be developed and demonstrations must be installed to test their relative effectiveness at improving water quality.
7. Soil bioengineering models must be further developed. Systems of various “guaranteed” effectiveness must be designed and tested on streams larger and smaller than Bear Creek. Additional species of shrubs must be identified that can be used in place of willow, especially where beaver may become a nuisance to the system.
8. Willow posts can be used to slow gully erosion, but designs must be developed that will fit various sizes and depths of gullies found in varying soil types.
9. We believe the riparian zone management system that we are developing is adaptable to the urban environment, but research is needed to identify the different inputs and problems found in that environment.
10. There is a need to conduct research on the benefits and costs of these systems, especially on the numerous intangible benefits of the system. Research is also needed on the perceptions of landowners to the need for riparian zone management systems and their willingness to adopt such systems.
11. Watershed level studies are needed to assess the amount of land that would actually be taken out of row-crop or grazing production with the installation of a riparian zone management system. A 66 ft wide system, on both sides of a stream, encompasses 16 acres of land in a mile length of stream. It is doubtful that this much land is taken out of row-crop production because of meanders and crop loss from flood events that occur in more than two or three years out of every five. These studies also should include estimates of the reduction in sediment and chemical loading to the stream if vulnerable riparian areas were managed by the model system. Estimates should include the percentage reduction that would occur with various widths of buffers, and various numbers of soil bioengineering systems applied. These kinds of information are needed for policy makers who are looking for the positive impacts of cost-share programs, etc.
Ambuel, B and S.A. Temple. 1983. Area-dependent changes in the bird communities and vegetation of southern Wisconsin forests. Ecology 64:1057-1068.
Castelle, A.J., A.W. Johnson, and C. Conolly. 1994. Wetland and stream buffer size requirements – a review. J. Environ. Qual. 23:878-882.
Cooper, J.R., J. W. Gilliam, R.B. Daniels, and W.P. Robarge. 1987. Riparian areas as filters for agricultural sediment. Soil Sci. Soc. Am. J. 51:416-420.
Crumpton, W.G. and J.L. Baker. 1993. Integrating wetlands into agricultural drainage systems: predictions of nitrate loading and loss in wetlands receiving agricultural subsurface drainage. Pages 118-126 in J.K. Mitchell, editor. Integrated Resource Management and Landscape Modification for Environmental Protection. American Society of Agricultural Engineers. St. Joseph, MI.
Crumpton, W.G., T.M. Isenhart, and S.W. Fisher. 1993. Transformation and fate of nitrate in wetlands receiving nonpoint source agricultural inputs. In G.A. Moshiri, editor. Constructed Wetlands for Water Quality Improvement. Lewis Publishers. Chelsea, MI.
Finch, D.M. 1989. Habitat use and habitat overlap of riparian birds in three elevational zones. Ecology 70:866-880.
Isenhart, T.M. 1992. Transformation and fate of nitrate in northern prairie wetlands. Ph.D. Dissertation. Iowa State University. Ames, IA.
Jacobs, T.C. and J.W. Gilliam. 1985. Riparian losses of nitrate from agricultural drainage waters. J. Environ. Qual. 22:467-473.
Karr, J.R. and K.E. Freemark. 1983. Habitat selection and environmental gradients: dynamics in the Astable@ tropics. Ecology 64:1481-1494.
Lowrance, R.R. 1992. Groundwater nitrate and denitrification in a coastal plain riparian forest. J. Environ. Qual. 21:401-405.
Lowrance, R.R., R. Leonard, and J. Sheridan. 1985. Managing riparian ecosystems to control nonpoint source pollution. J. Soil Water Conserv. 40:87-91.
Lowrance, R.R., R. Todd, J. Fail, Jr., O. Hendrickson, Jr., R. Leonard, and L. Asmussen. 1984. Riparian forests as nutrient filters in agricultural watersheds. BioSci. 34:374-377.
Margules, C and M.B. Usher. 1981. Criteria used in assessing wildlife conservation potential: a review. Biological Conservation 21:79-109.
Osborne, L.L. and D.A. Kovacic. 1993. Riparian vegetated buffer strips in water-quality restoration and stream management. Freshwater Biol. 29:243-258.
Peterjohn, W.T. and D.L. Correll. 1984. Nutrient dynamics in an agricultural watershed: observations on the role of a riparian forest. Ecology 65:1466-1475.
Rafe, R.E., M.B. Usher and R.G. Jefferson. 1985. Birds on reserves: the influence of area and habitat on species richness. Journal of Applied Ecology 22:327-335.
Ratcliffe, D.A. 1977. A Nature Conservation Review. Cambridge University Press. Cambridge, MA.
Smith, T.M. and H.H Shugart. 1987. Territory size variation in the ovenbird: the role of habitat structure. Ecology 68:695-704.
Stauffer, D.F. and L.B. Best. 1980. Habitat selection by birds of riparian communities: evaluating effects of habitat alterations. J. of Wildlife Management 44:1-15.