Water Quality Effects of Multifunctional Working Buffers for Seasonally Wet Farmland

The use of private land for agricultural production includes regulations governing specified distances from watercourses, waterbodies, wetlands, or tidal shorelines. Most states and localities adopted these practices in the 1960s, calling these specified distances “setbacks” or “buffers”, serving to protect critical areas from pollution, for preservation of habitat, and the protection of structures from flooding or erosion. These buffers are intended to separate waterbodies from potentially polluting activities. For commercial agricultural lands, these distances are typically lesser distances for the purposes of production.

While buffers are quite common in regulations across the United States, very little research has been done regarding the effectiveness of these setbacks in preventing contamination from non-point source pollution.

Measurements of soil and water resources in their existing condition, or quality, are typically collected within the top six inches of soils. These top six inches are the most important indicators for non-point source pollution runoff, where surface waters mix with soil. Runoff becomes more important relative to the nutrient load within seasonally-wet areas and other critical areas, where nutrient loading may be significant for aquifer recharge, transport via subsurface drainage, and/or downstream discharge into waterways.

The scientific efficacy of working buffers is largely unknown due to a lack of scientific research providing soil- and water-quality data. It is the intention of this research to lay the foundation for obtaining the necessary metrics for both policy decision-makers and producers, to find a win-win situation between buffer regulation and production for farmers.

During this three-year grant, we utilized three pilot sites, one within each of the Skagit, Snohomish, and Whidbey Island Conservation Districts’ boundaries. In approximately the first six months of the grant, we performed literature and desktop reviews to establish optimal location placement and equipment type for each individual pilot site, based upon hydrogeography and soil type, to maximize the efficiency of soil- and water-quality data collection. Prior to any field alterations we will install all research-related equipment, take appropriate samples, and collect a year of baseline data. Immediately following we installed agroforestry orchards within known seasonally-wet buffers on the commercial agricultural pilot sites, collect a year’s worth of data downstream of the installed working buffer and continue collecting baseline data upstream of the altered area, as a control. In the last six months of the grant, with the first-ever data set collected, we began compiling data for future analysis at a later stage of research. Our long-term goal was to provide sufficient research in a multi-phased project, to obtain sufficient data and information over many years, to elicit local policy change for the benefit of both the environment and agriculture producers.

Objective 1: Strategy identification

The intention of this objective was to complete an analysis of the conditions of each of the three pilot sites, to ensure that the selection of equipment, sampling locations, quality assurance, and a Quality Assurance Project Plan (QAPP) are thoroughly examined. A hypothesis and null hypothesis was identified for each location, as each site was treated as independent pilot sites.

• We selected three fields for this experiment based on the following criteria: 1) landowner willingness; 2) presence of wet areas; 3) geographic distribution for visibility across all conservation districts. We conducted a desktop review to establish watershed characteristics including topography, drainage patterns, climate data, water table, and available geohydrology data. We analyzed pre-existing soil and/or water quality impairments for each site and highlight noted impairments in relation to current regional standards.
• Through desktop review and on-site visits, we determined the appropriate data collection equipment for purchase and installation at each pilot location. We used both automated samplers and manual sampling for more comprehensive data collection and to keep costs down. The strategy identification intended to clarify:
  • Hydrogeology
  • Climate data
  • Drainage flow
  • Water table
  • Watershed boundaries
  • Soil type
  • Anticipated equipment includes water-level loggers and in-situ nutrient collection for water-quality; shovels, containers, and personal protective equipment for soil-quality sampling.
• Field personnel were trained on soil- and water-quality QA/QC methodology, equipment operation, basic hydrology, and safety considerations. Field personnel made monthly trips to the sites to collect data and retrieve soil and water samples.
  • We followed USGS runoff methodology and sampling protocol. 
• QAPP
  • USGS methodologies were followed for each individual pilot site.

Objective 2: Establishing baseline data through the installation of water quality monitoring equipment prior to the installation of working buffers

The intention of this objective was to obtain data upstream and downstream of each buffer prior to any alterations, to provide relative analysis of  impacts of  installation of the working buffer on soil and water resources. Installation of in-situ temperature and water-loggers, nutrient collection, and ongoing soil and water testing prior to installation of the working buffer allowed for relative analysis of potential benefits of a working buffer and existing buffer

• We established a twelve-month baseline dataset for each site prior to installation of working buffers.
• We supported the Education Team in their video production showcasing the process.

Objective 3: Working buffer installation

The intention of this objective was to install an agroforestry orchard within each working buffer, as the parameter of change to be measured.

• Based upon information obtained in the previous objective, an agroforestry orchard was installed within the buffer of the seasonally wet areas at all three trial sites.
• A desktop review was conducted to ensure that plant selection was suitable for soil and water conditions. Components identified include:
  • Best implementation period to suit producer needs, while considering environmental sensitivities, such as the wet-season
  • Density of plantings
  • Number of plantings
  • Types of grafting, if necessary, for suitability in saturated soils
  • Mulch and amended soils for increased planting success
• Location of the plantings was carefully considered, to include areas that leave upstream soil- and water-quality sampling locations, that continue to serve as the hypothesis control throughout the grant.
• Success of plantings was identified as a percentage of plants established vs. failed, within the working buffer of each pilot location.
• We collaborated with the Education Team to tie in opportunities for producer and volunteer participation.
• We continued to support the Education Team in their video production showcasing the process.

Objective 4: Measure soil- and water-quality effects of a working buffer at each of the three newly established trial sites 

The intention of this objective was to measure soil- and water-quality changes downstream of installed working buffer, to examine the hypothesis.

• We collected samples in waterways, drainage pathways, or points of concentrated flow, with at least two (2) temperature and water-logger stations, one upstream and one downstream, and at least ten (10) soil sampling locations, at each pilot site. Soil-quality sampling stations were located in-field or at drainage outlets, depending on the topography, as assessed in the desktop review. Each of these pilot sites were easily accessible to allow for year-round sampling, and to include at least one storm-event sampling at each pilot site, as well as meteorological data from the nearest WSU weather station.
  • Periodic soil sampling included: percent solids, percent water, total phosphorus, Fe-bound phosphorus, Fe-iron, nitrate plus nitrite-N, ammonium-N.
  • Soil sampling occurred monthly and included total phosphorus, total nitrogen, total potassium, pH, and alkalinity. 
  • Water sampling included: total solids, total suspended solids, suspended sediment, dissolved reactive phosphorus, total dissolved phosphorus, total dissolved solids, nitrate plus nitrite-N, ammonium-N, total phosphorus, and specific conductance. Total Kjeldahl nitrogen was also measured. 
  • Ongoing water sampling will occur monthly and include: total phosphorus, total nitrogen, total potassium, pH, and alkalinity. 
  • Total working buffer sampling included ~12-18 months’ worth of data for initial analysis
• We supported the Education Team for farm walks.
• We continued to support the Education Team in their video production showcasing the process.

Objective 5: Compile the data

The intention of this objective was to collate and synthesize the data collected into written and visual representation for initial data collection, during the first phase of research attempting to address the hypotheses and null hypotheses identified during Objective 1, for each individual pilot site

• Through data analysis, we identified unexpected results or data gaps that future research may need to address.
• Maps, charts, and a summary of the initial impacts after the installation of each working buffer were developed.
• Success of the research was identified at this stage–e.g, were we able to successfully capture data in soil- and/or water-quality, as a direct result of the working buffer AND were the results repeatable at all three pilot sites.
• Peer review by stakeholders and volunteer scientists

Objective 6: Identify what changes are observable within the timeline of this grant and where further research is needed

The intention of this objective was to review the data to identify what changes are necessary in the next phase of the project, to ensure future success in identifying whether or not working buffers can sustain or improve soil- and water-quality while also increasing production margins for farmers; a check and balance to ensure that the research design is capable of meeting the objectives identified in this grant.

• Data analysis began to show challenges or successes of new in-field buffer systems, but are unlikely to be conclusive.
• The above analysis began to show us a comparison of newly established in-field working buffer systems and initial effects of the first year, on soil- and water-quality.
• Further data collection to observe soil- and water-quality data on agroforestry working buffers as they age, to include more established systems with larger root volumes, will be necessary for a comprehensive look at these systems.
• As this project is the first step in a multi-phased project, no final conclusions about the efficacy of multifunctional working buffers can be identified as a result of the present data set.
• We submitted our findings for peer review stakeholders and volunteer scientists.
• We continued to provide support to the Education Team to promote public awareness of multifunctional working buffers.

Objective 7: Identify “Lessons Learned” with possible benefits/limitations of working buffer systems to improve water-quality

The intention of this objective was to reflect upon the first phase of this multi-phase project to ensure that “lessons learned” are shared and identified throughout its duration, and not just at the end. We anticipate significant interest in this research as it is the first of its kind.

• Analysis of data for outliers identifying potential causes/sources was done by comparing automatic temperature and water-logger equipment data, field notes, sample data sheets, and laboratory data results.
• We organized data by soil- and water-quality, and -quantity by laboratory code constituent concentrations. When we received results, we matched them with time and location data for each individual pilot site. All information was placed in a data-summary spreadsheet for each station, checked, and finalized at the end of each water year.
• Analysis of the weather stations, producer experience, baseline data, and constituent loads were determine whether the first years data represents a “typical” runoff event or is anomalous, potentially influenced by upstream activities. We compared our findings with “typical weather” as defined by an analysis of 10 years worth of data to establish prior information on a “typical” weather year, using the WSU agronomical weather stations, closest to each pilot site location.
• We provided support to the Education Team to promote public awareness through public events and/or webinars.
• Continued to support the Education Team with video production.
• While the overall goal was to assess whether working buffers are efficacious at reducing pollutants, this phase of the grant focused on the collection of baseline data with descriptions of soil- and water-quality to be used statistically during later phases of continued research.