Performing Department
(N/A)
Non Technical Summary
Soil contamination with PFAS (perfluoroalkyl and polyfluoroalkyl substances) from historical sludge applications is an emerging crisis in agricultural. Maine is at the forefront of this crisis, and forage producers (dairy, beef, and hay) are one of the most impacted groups. The goal of this project is to equip farmers, in Maine and elsewhere, with management strategies to reduce risks associated with growing forages on PFAS-contaminated land. Specific objectives are to 1. investigate if crop management practices (altering species, harvest timing, harvested products, and cutting height) can reduce PFAS concentrations in harvested forages, 2. facilitate farmer-driven research to "field truth" these PFAS mitigation strategies on their farms, and 3. support adoption of PFAS mitigation strategies by farmers. We expect to see the largest differences in PFOS uptake rates among forage species and among harvested products, making these viable PFAS mitigation strategies for farmers with moderately contaminated soil. For farms with lower soil concentrations (but above screening levels), we expect that harvesting at later growth stages and maintaining a low cutting height will be shown to be viable PFAS mitigation strategies. This project will produce actionable information for farmers, farm advisors, and policymakers to use in short-term responses to PFAS contamination and contribute critically needed data for longer-term responses to this widespread emerging pollutant.
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The project goal is to equip farmers, in Maine, the U.S. and elsewhere, with management strategies to reduce the risks associated with growing forages on soil contaminated with PFAS. Specific objectives are to:Investigate the effect of species selection, crop type, harvest timing, and cutting height on PFAS uptake by forage crops.Facilitate farmer-driven research on PFAS mitigation strategies for forages.Support adoption of PFAS mitigation strategies for forages.
Project Methods
Objective 1This project leverages and expands the scope of a one-year trial funded by the American Farmland Trust's Rapid Response Funds. The proposed project will allow us to:1)Add plant partition analysis to help explain possible harvest timing effects,2)Add an assessment of how cutting height affects PFAS concentrations of harvested hay, and3)Repeat the entire trial, including the additional comparisons, for a second year to test the reliability of first year results.The trial is located on a former organic dairy farm field that was contaminated with PFAS through repeated applications of sludge from a municipal wastewater treatment facility in the 1990s, resulting in a soil PFOS concentration of 114 ppb dw. The trial was initiated in August 2023 with the seeding of five perennial forages: three grasses (timothy, tall fescue, and orchardgrass), two legumes (red clover and alfalfa), and one grass-legume mix (timothy-red clover). In the spring of 2024, three annual forages will be added to the trial (pearl millet, oat, and field pea). The trial is a randomized complete block design with four replications. Plots are 1.8 x 4 meters. An adjacent set of 3- x 4-meter plots, also in a complete block design with four replications, will be planted to silage corn to compare corn harvested for silage, snaplage, and grain.Each forage species will be sampled in year one when it reaches a growth stage considered "optimal" for forage production (ex. boot stage for grasses) and a growth stage considered "late" (ex. anthesis). Plants will be cut 8 cm above the soil surface from four randomly located, 0.05-m2 quadrats and placed directly in one pre-labelled ziplock bag (i.e. composited), weighed, and submitted for PFAS analysis. Plants from four additional quadrats per plot will be similarly sampled and submitted for forage quality analysis. Using a 40-cm soil probe, ten cores will be taken across each plot, divided into 0-15 cm and 15-30 cm depths, and composited by depth. Soil samples will be well-mixed, have stones and roots removed, and subsampled for PFAS analysis and soil chemical and physical properties. PFAS analysis of soil and plant tissue will be conducted by a private laboratory using isotope dilution LC-MS/MS compliant with Department of Defense QSM 5.4 Table B-15 for 28 analytes. Forage quality will be analyzed by a private laboratory using near infrared reflectance spectroscopy (NIR) and will include dry matter, crude protein, lignin, starch, fat, acid detergent fiber, and ash-free neutral detergent fiber. Soil chemical and physical properties will be determined by the UMaine Analytical Laboratory and include soil pH, organic matter, phosphorus, iron, aluminum, total organic carbon, and soil texture. We will partition the timothy, orchardgrass and red clover plant samples at both harvest dates into leaf, stem, and head fractions before weighing and submitting for PFAS and forage quality analysis. We will further partition timothy into leaves and stems in the 8-to-16-cm section of the plant and leaves, stems, and heads in the above-16-cm section of the plant to investigate possible cutting height effects (8 cm vs. 16 cm).The survival of the perennial forages will be assessed in early spring and reseeded as needed by broadcast seeding. Annual forages will be re-established in the same plots as year one to avoid rotation as a confounding effect. Sampling methods for year two will be identical to the methods for year one described above.Response variables for analysis will be plant PFOS concentrations and soil-to-plant transfer factors (plant PFOS concentration, dw, divided by soil PFOS concentration, dw). Similar analyses will be done for other PFAS detected in plant tissues. The effect of forage treatments will be analyzed using generalized linear modeling with treatment and replicate as fixed and random effects, respectively, followed by contrasts to assess the effects of perennials vs. annuals, legumes vs. grasses, harvest timing, and harvested crop. The corn trial will be analyzed separately from the main trial, and confidence intervals will be used to compare corn treatments with main trial forage treatments. Separate analyses will be conducted to investigate the effect of plant part (leaf vs. stem vs. head) on PFOS concentrations for timothy, orchardgrass, and red clover and the effect of cutting height for timothy. Principal components analysis will be used to identify which, if any, forage quality parameters, contribute to variation in PFOS concentrations and transfer factors. To explore the possible economic tradeoff between minimizing PFOS concentrations and maximizing forage quality, MILK2016 (University of Wisconsin) will be used to estimate milk yield t ha-1 based on perennial forage yield and quality parameters, and converted to $ ha-1 using current milk prices, as outlined by Undersander et al.Objective 2We will collaborate with four farmers with PFAS-affected fields to "field truth" possible PFAS mitigation strategies on two farms in years 2 and 3 in replicated strip trials. Farmers will compare a PFAS mitigation strategy they identify as promising for their forage production system with their standard practice to one or two alternative practices. Strips will be replicated four times. Plots will be sampled for soil chemical and physical characteristics, soil and plant PFAS concentrations, and forage quality. Sampling methods will be the same as in the plot trial with the exception that we will employ co-located sampling, where soil will be sampled directly from the clipped quadrat area, to avoid experimental error due to spatial variability in soil PFAS concentrations.Objective 3We will use a variety of methods to increase understanding among farmers and farm advisors of the factors affecting PFAS uptake by forage crops and the options for reducing PFAS in harvested forage. Each winter we will host a series of two to three meetings for forage producers who have fields with PFAS contamination to share knowledge and experiences, learn about factors affecting PFAS uptake, discuss options for their land, and generate new ideas. While the primary objective of the FFP Network is to equip farmers with the information they need to make informed choices about how to address PFAS contamination of their forage fields, we expect participants also to find substantial value in connecting with other PFAS affected farmers. Another outcome will be an informal needs assessment generated when the group discusses and identifies critical gaps in information or support.Each year, we will find at least two opportunities to talk about PFAS mitigation in forage production and present project results at meetings and conferences targeting forage producers and farm advisors. We will produce one fact sheet to summarize state guidance on allowable levels of PFOS contamination in beef and milk, how PFOS moves from soil to plants to animals, what is known about factors that affect movement, and management strategies to reduce PFOS concentrations in forages, and to highlight results from our plot trials and farmers' strip trials. An interactive online version will be created and posted on Extension's "PFAS and the Maine Food System" webpage (https://extension.umaine.edu/pfas/) and linked on our collaborators webpages.Impact EvaluationWe will use both formative and summative evaluations. Participants in each winter's FFP Network meetings will be asked to fill out a questionnaire after the last meeting of the winter to assess learning and identify topics and approaches for future meetings. A summative evaluation will be distributed at the end of the all project participants to assess which aspects of the project had most value, learning outcomes, what actions they (or the farmers they work with) took as a result of what they learned, the impact of those actions, and remaining research and extension needs.