1993 Annual Report for AW93-013
A High-Input Crop Production System in Coastal California as a Model for Developing Indicators of Agroecosystems Sustainability
Summary
Develop a baseline characterization of potential indicators of agroecosystem health at a long-term agricultural research site in the Elkhorn Slouch watershed, Monterey County, California.
Abstract of Results
Our original proposal to the USDA-ACE Program was for a three year project to examine the influence of vegetated buffer strips on nonpoint source pollution from crop lands and its influence on an adjacent wetland. We received one year of funding which allowed us to complete a baseline characterization of the site. Planting of vegetated buffer strips will begin in 1995, with funding from another source. Data from this study will be used to assess the relative effectiveness of different vegetated buffer strips treatments.
The Azevedo Ranch research site encompasses 150 acres, approximately 120 of which are currently in strawberry cultivation. The land, which is owned jointly by The Nature Conservancy and the Monterey County Agricultural and Historical Land Conservancy, will be managed in perpetuity as a research and demonstration site for sustainable land management practices. The property will be divided into a wetlands buffer zone surrounding three "pocket marshes" and an upland agricultural zone. The buffer zone, which is currently in cultivation, will be restored with native vegetative cover including native bunch grasses, Coast Live Oaks, and maritime chaparral. The upper agricultural zone will encompass 83 acres and will eventually be converted to low-input sustainable agriculture. The overall goal is to develop models, for the greater watershed, of ecologically and economically sustainable methods for crop production. Because this is a report of baseline characterization of the study site, our emphasis is on findings, rather than applications or farmer adoption, which will come in a later phase of the long-term project for which funding is being actively sought.
The land-use history, site and soil characteristics, infiltration rates, earthworm abundance, nitrogen and phosphorous in runoff, nitrate in soil water, and sediment transport, and arthropod populations were collected and quantified for the upland portions of the site. In the wetlands we quantified benthic invertebrates, salt-marsh plants, and water quality (temperature, salinity, oxygen, turbidity, pH, and nutrients, including total phosphorous, phosphate, nitrate, nitrite, and ammonium).
New Hypotheses
Our work to date at the Elkhorn Slough has generated increased interest in examining the potential benefits of vegetated buffer strips between the cultivated portions of the Azevedo Ranch and the wetlands. With additional funding, we will study the mechanisms by which vegetated buffer strips can be used to reduce the movement of nonpoint source pollutants from farmland to wetland. We are specifically interested in the transport and fate of sediment, nitrogen and phosphorous in surface water, and nitrate-nitrogen in sub-surface water. We will compare native perennial bunch grass vegetated buffer strips with vegetated buffer strips comprised of annual grasses. We will measure nitrogen pools and pathways in order to contribute to our understanding of nitrogen budgets in the row-crop/vegetated buffer strips systems. Results of this study will be used in the design of vegetated buffer strips for Mediterranean climates, with the goal of protecting wetlands while developing ecologically sound agricultural practices. This study will also contribute to the regionally important goal of restoring native wetland and upland habitat at Elkhorn Slough, and in other California wetland areas.
Reported in 1995