Tulelake is a high mountain valley on the California Oregon border where irrigated agriculture coexists adjacent to the Tulelake National Wildlife Refuge. The refuge is a critical part of the Pacific flyway and with Lower Klamath Refuge supports 1 million migrating waterfowl, annual waterfowl production of 40,000, and habitat for 411 wildlife species. Concerns facing the basin include; degeneration of wetland habitat, hypereutrophication, pesticide use, declining populations of endangered fish and declining crop productivity due to build up of nematodes and other soil pathogens.
Improved management strategies to sustain agriculture and provide high quality wildlife habitat are needed. One strategy proposed is to flood areas of existing cropland to create new diverse wetlands, and drain areas of existing wetland to create cropland free of soil borne pathogens. In this project we established pilot studies to assess the feasibility of cropland/wetland rotations in terms of crop production, pest control, quality of wildlife habitat created, effects on water quality, and socioeconomic impacts. A major goal was to communicate with different sectors of the local community, Federal/State agencies, researchers, and other organizations active in Klamath Basin issues, and to incorporate different perspectives into this study as it developed.
During the course of this grant we completed baseline soil and water sampling of all the pilot sites, and initiated wetland/cropland rotational management at each location. Vegetation development, impacts on water quality and seasonal water use were monitored at selected sites. While variation in vegetation development across pilot sites was observed, abundance of desired wetland species was achieved in most sites by the second year of seasonal flooding. Water quality impacts of seasonal wetlands depended upon time of drainage and the degree of subsurface to surface drainage. A GIS based hydrological model is being developed to predict water use and quality impacts of different rotational land use schemes. Preliminary data suggest that newly created permanent marshes can improve surface water quality for much of the season, and significantly reduced nematode populations.
A digitized base map of the basin was developed in cooperation with the US Bureau of Reclamation office in Klamath Falls. Multiple layers of inherited physical and socioeconomic information together with data collected from the pilot sites have been entered to create a spatial database for the area. This GIS database is being used to develop models to assess the impacts of various management options on economic and environmental aspects of the ecosystem.
• To conduct pilot studies to assess the feasibility of wetland/cropland rotation (flooding of existing cropland to create new wetlands, and drainage of existing wetland to create new farmland) as a long term management option for sustainable coexistence of irrigated agriculture and wetland reserves in the Tulelake basin.
• To determine the impacts of wetland/agriculture rotations using various management strategies on: water quality, seasonal dynamics of nutrient release/immobilization, pesticide residue movement, crop productivity, development of marshland vegetation and the quality of wildlife habitat created.
• To compare the ability of managed wetland systems and irrigated cropland to remove or immobilize nutrients and other residues from agricultural drainage water.
• To test the utility of short term flooding cycles to control soil borne pathogen and nematode populations within irrigated cropland rotations, and determine the extent of use of these temporary wetlands by wildlife.
• To assess the socioeconomic impacts and policy implications associated with rotational wetland/agriculture management systems.
• To coordinate this project with other research/planning activities in the Klamath Basin, and facilitate involvement of different community groups, State and Federal Agencies and other organizations in the development of the pilot projects.
Creation of pilot study sites
We have established the following pilot sites:
• Short cycle rotation: 3 years wetland / 3-4 years cropland
• Two locations: one with 3 x 40 ac units and one with 2 x 40 ac units.
• Long cycle: 20+ years in wetland / 20+ years in cropland
• Transition from cropland to wetland: 3 locations of 100, 120 and 240 ac.
Baseline soil samples were collected in a nested pattern, with the main grid 200′ by 200′. These data are being used to generate baseline soil maps, and to determine spatial variability patterns of key soil characteristics. During the cropping phase of the rotations, land is leased by farmers and managed in accordance with agreed upon project guidelines. During the wetland phase, the sites are managed by the USFWS staff of the Tulelake Wildlife Refuge. The timetable of management for each short cycle site is given below.
Nutrient and water budgets are being developed for each site. Water quality, nutrient contents and inflows/outflows were monitored biweekly throughout the year. Soil nutrient pools and plant productivity and nutrient uptake were also monitored each growing season, Results to date have shown that the rate of establishment of wetland vegetation varies with location, but that productive seasonal wetlands can be created in the first or second season after flooding cropland. This seasonal marsh effectively reduced available N and P in the surface water, however, when water levels were drawn down in June to establish the desired annual moist soil vegetation, movement of water through the soil profile resulted in significant reductions in water quality associated with lower dissolved oxygen and higher available P in subsurface drainage water. The severity of this effect depended on timing, with dissolved oxygen falling markedly after approximately 130 degree days above 5º F were accumulated. Further, water moving through the subsoil showed greatly decreased dissolved oxygen and peaks of high ammonia. Thus net water quality impacts of seasonal marshes will depend on timing of release of water from them, the balance of surface and subsurface drainage, and the volume flows and background water quality of the drainage canals or wetlands they are drained into. To address the latter, and to model patterns of water consumption and flows under different land management options, we developed a hydrologic model for a large section of the refuge. This model, called “Flatland” is still being tested and refined. It is based upon network analysis to route water flows, with the amount of inflow determined by water consumption within each cell, and drainage outflow by soil water content and inflow rates. This model will be used to evaluate seasonal water use and water quality effects of different refuge management options under different water availability scenarios.
• Development of digitized base map and GIS database for the refuge area
In cooperation with the USBR, we developed a digitized base map of the study area, and a GIS database that includes topographic data, infrastructural information, cropping histories, crop management data, historical economic and water allocation data, water flows, soil characteristics etc. This is being used to model the economic and environmental costs/benefits of different management options using a combination of existing information and data from the pilot studies. Current modeling efforts are focusing on hydrological and water quality (see above), and economic productivity and management relationships.
Conceptually this project has broad implications, since it explicitly aims to develop management options that enable agriculture and wetland habitat to coexist in a healthy and sustainable way within the same landscape. It is a unique approach to wetland refuge management, and ideas and lessons learned in the process of the pilot research may have applications in other multiple use conflicts. Specific results to date indicate that seasonal flooding as tested in the short cycle wetland rotations has the potential to reclaim nematode-infested fields while also providing improved wetland habitat for waterfowl within a short time frame (1-2 years). Water quality effects of seasonally-managed wetlands appear to be highly dependent on the balance between surface and subsurface water flow through the wetland. Initial data showed an improvement in surface water quality in the wetland, but a deterioration in water quality as water moved through the soil profile and left the wetland in drainage water.
At this point data from this project will be used by a planning and implementation team recently appointed by the USFWS refuge staff to develop a phased implementation plan for wetland cropland rotation in the Tulelake National Wildlife Refuge. Plans are already underway to initiate a short cycle flooding fallow on a number of lease lots in the refuge with serious nematode and white rot problems in 1999-2000. Producer involvement continues to be significant, through the advisory committee (7 growers), and leasing of pilot sites during cropping phases (6 growers to date).
Educational & Outreach Activities
Presentations made based on project, 1994-98:
1994. Wetland/Cropland rotational management for the Tulelake basin. Presentation, Tulelake Growers breakfast meeting, Tulelake, CA.
1994 Wetland/Cropland rotational management for the Tulelake basin. Presentation, Annual Potato Day, Fairgrounds, Tulelake, CA.
1994. Wetland/Cropland rotational management for the Tulelake basin. Annual Vegetable Crops workshop, Davis, CA
1995. Scale, scope and a hierarchical view of agroecological research. Invited lecture, Board of Environmental Studies, UCSC,
1995. Sustainable Agriculture Research Presentation to U.S. Representative Riggs and members of the House of Representatives Agriculture Appropriations Committee, Napa CA.
1997. Costa, F., C. Shennan and W. M. Jarrell. 1997. Use of GIS to create spatial indices of soil quality. ASA CSA SSSA meeting, Los Angeles, CA.
1997. Jarrell, W.M. C. Shennan, F. Costa and M.M. Abrams. 1997. Water quality in wetland agricultural rotation. ASA CSA SSSA meeting, Los Angeles, CA.
1997. Shennan, C; W.M. Jarrell and F. Costa. Wetland/cropland rotational management to improve wetlands and sustainable agricultural production in the Tulelake basin. In: Proceedings of “Interactions: Investigating ecosystem dynamics at a watershed level” Soil and Water Conservation Society Conference, Athens, GA. April 13-16, 1997.
1998. Wetland cropland rotational management to improve wetlands and sustain agricultural production in the Tulelake basin. Presentation, SARE 10th Anniversary conference. Austin, TX
1998. Wetland/cropland management in the Tulelake basin: issues of multiple land use. Invited public lecture Humboldt State University.
1998. Methodological approaches for assessment of ecosystem health as applied to agriculture in a multi land use environment. Seminar, Humboldt State University.
1998. Assessing sustainability of a managed multi use ecosystem: a case study of wetland and cropland management in the Tulelake National Wildlife Refuge, California. Presentation at the “Asia Pacific High Level Conference on Sustainable Agriculture,” Beijing, October 1998. AAAS CAST.
1999. Assessing sustainability of a managed Multi use ecosystem: at the interface between cropland and wetlands. Invited presentation at “Ecologies of the Coast” symposium, Monterey Bay Regional Studies program, UCSC.
1996 Shennan, C. (Ed). Sump rotation newsletter, Vol 2. Spring/summer 1996. Potential for we of cover crops in the Tulelake basin; call for on farm research participants; and testing of onsite technique for monitoring potato N status.
1996 Shennan, C. (Ed). Sump rotation newsletter, Vol 1. Winter 1996. Overview of cropland/wetland rotation research in the Tulelake basin.
1997 Shennan, C. et al. Rotational management of wetlands and croplands in the Tulelake basin. Report to UC Intermountain Research and Extension Center.
1997 Shennan, C., W.M. Jarrell and F. Costa. Wetland/cropland rotational management to improve wetlands and sustainable agricultural production in the Tulelake basin. In: Proceedings of “Interactions: Investigating ecosystem dynamics at a watershed level,” Soil and Water Conservation Society Conference, Athens, GA. April 13-16, 1997.
1998 Assessing sustainability of a managed multi use ecosystem: a case study of wetland and cropland management in the Tulelake National Wildlife Refuge, California. In Proceedings of the Asia Pacific High Level Conference on Sustainable Agriculture”, Beijing, October 1998. AAAS-CAST.
1998 Bode, C.A. et al. Sump Rotation Research Report. Flatland: a hydrologic model for the Tulelake NWR.
1999 Shennan, C. et al. Sump Rotation Research Report: Research Overview.
1998 Gjerde, M.G. et al. Sump rotation Research Report: Economic analysis.
1999 C. Shennan. (In preparation). Evaluation of wetland cropland rotations as a multi use landscape management option. (For submission to Ecological Applications)
1999. Jarrell, W.M. et al. (In preparation). Water quality impacts of seasonal wetland management in the Tulelake basin, CA. (For submission to Journal of Environmental Quality)
1996 Costa, F., M. Abrams, W. M. Jarrell and C. Shennan. Spatial variability of soil quality parameters from a wetland/cropland rotation system. “Critical Methodologies for the Study of Ecosystem Health” conference, UCD, CA.
1996 C. Shennan, F. Costa, and M. Abrams. Spatial variability analysis of soil fertility parameters from alternative cropping systems. Annual Meeting ASA/CSSA/SSSA, November.
1996 Costa, F., M. Abrams, W. M. Jarrell and C. Shennan. Spatial variability of soil quality parameters from a wetland/cropland rotation management scheme. Annual Meeting ASA/CSSA/SSSA, November.
1997 Costa, F., C. Shennan C. M. Bode and W. M. Jarrell. Use of GIS to create spatial indices of soil quality. ASA-CSA-SSSA meeting, Los Angeles, CA.
1997 Jarrell, W.M. C. Shennan, F. Costa and M.M. Abrams. Water quality in wetland agricultural rotation. ASA-CSA-SSSA annual meeting, Los Angeles, CA.
1998. Wetland cropland rotational management to improve wetlands and sustain agricultural production in the Tulelake basin. In Proceedings of SARE 10th Anniversary conference, Austin, TX.
1998 Costa, F., C. Shennan and W. M. Jarrell. 1998. ASA-CSA-SSSA annual meeting, Baltimore, MD.
Areas needing additional study
Sample analysis and publication efforts were impeded in 1997 by the relocation of the project director to a new position, and by the subsequent delays in Rind transfer which put much of the project on hold. A conceptual overview paper is in preparation for submission to Ecological Applications, two additional papers are also being drafted, and we have been invited to contribute a chapter to a book on agriculture and conservation. The bulk of the backlog of ample analysis has been completed and with data from the 1998 field season now available we have sufficient replication over time and completion of wetland cycles in two pilot sites to justify publication. We have continued to monitor the transition back into fanning on these sites in 1999. We will continue providing updates on the research through the newsletters and presentations to a wide range of groups: farmers, environmental groups, agency personnel, politicians, researchers, extension agents and students.