Progress 09/15/24 to 09/14/25

Outputs
Target Audience:Our long-term goal is to increase adoption among organic HT growers of the agroecological practice of cover cropping to improve productivity, environmental outcomes, and resilience associated with intensive HT production environments. As the use of legume cover crops has potential to reduce farmers' need for purchased manure-based fertilizers in their high tunnels, adoption of cover crops may be particularly valuable for farmers with limited resources. This project includes a focus on education and outreach for emerging farmers, broadly defined as those who face barriers to traditional farmer support programs. These farmers form a crucial and growing segment of the local food system and the organic vegetable production community in the Midwest and Northeast regions. In particular, emerging farm communities in our regions include many new American growers who bring strong farming knowledge from their previous countries, and are actively seeking to adapt their practices to succeed in a northern US context. Our project represents part of a broader effort to connect these farmers with public resources and programs including University Extension support and state and federal programs for farmer education and financial support. In Y2, the target audience for our activities has largely continued to be current organic high tunnel growers, through participation in our field trials and HT management course. In Y1, because recruitment was taking place concurrently with the refinement of experimental treatments and trial instructions, on-farm trial recruitment was more heavily weighted toward mainstream and established organic farm communication networks, in order to ensure that we connected with farmers who are certified organic, comfortable communicating with the research team, and are already producing vegetables in existing high tunnels. In Y2, we have intensified recruiting within emerging farm communities through contacts at state and federal agencies and local organizations, and the cohort that we are working with through the SARE-PDP program (Project ENC24-237) of organization personnel and farmer mentors who provide technical assistance to emerging farmers. While we do not have detailed demographic data on trial enrollees, we are aware that our on-farm trial participant group contains several beginning farmers. In Y2 of the trial, we are excited that our new enrollees include a family who are prominent organic leaders and educators in the local Hmong farming community, as well as the farm team at the Fond du Lac Tribal and Community College ( FDLTCC ) farm, which engages indigenous students and community members. Our partners at FDLTCC have requested to host on-farm field days in the coming season. We held five hands-on field days associated with the high tunnel production course in project Y2. By opening attendance at these field days to the wider small-farm community (rather than only course participants) we were able not only to draw a critical mass of attendees to enable us to offer sessions on a wider range of management topics, but also to include more beginning and emerging farmers in our outreach. Two of the field days were conducted bilingually. Changes/Problems: Logistics of sample and data collection from FFs were more intensive than anticipated: because the planting/termination dates that farmers chose ranged widely, it was rarely possible for the research team to combine trips, so more travel time and mileage have been required than we originally anticipated, and in two cases focus farmers have been asked to collect and ship samples that the research team had originally planned to come to the farm to collect. Additionally, there were management changes at two of the farms, which resulted in some disruptions to communication. These difficulties resulted in some sampling timepoints being missed in our data collection for the Y1 fall timeslot However, due to the strong recruitment for this timeslot, we still expect to have more on-farm replicates than originally proposed, so we are confident that the quality of the full dataset will be strong. Some focus farm participants who had enrolled for the spring and summer planting timeslots did not plant their cover crops as planned, or fell out of communication with the research team while facing field-season pressures or personal challenges. To address this, we have 1) streamlined the enrollment process to take place closer to planting and to more clearly communicate trial procedures and expectations when farmers initially enroll, and 2) developed a communication plan in which each farmer has a primary contact on the project team, generally in their own region, and communication about trial milestones takes place largely through individualized contacts rather than group emails. We anticipate that, with a second year of recruitment, on-farm replication for these timeslots will be sufficient to allow statistical analysis of the data. As mentioned in our Y1 Annual Report, because Erik Heimark has moved to a new position with Renewing the Countryside (RTC), the 2025 and 2026 high tunnel producer courses are being offered through a RTC/UMN Extension collaboration. The original subcontract with Heimark's previous employer is in the process of termination, with support now provided to the new employer via a Professional Services process at the University of Minnesota. Course materials were moved to the Canvas LMS. These changes have resulted in surprising advantages, including improved course recruitment because participants do not need to register for college credit (which was a barrier in similar courses offered previously). What opportunities for training and professional development has the project provided? 25 HT farmers received in-depth training in HT management and production via co-PI Hoidal and Heimark's 9-week course. To date, 52 farmers participating in the field trials have gained hands-on experience with high tunnel cover crop planting, and will have the opportunity for peer-to-peer learning about successful practices and challenges through participant webinars scheduled for late October 2025. The project team has provided a detailed participant instruction document that includes information on legume cover crop species for different rotational timings, and instructions for planting, management, and termination. The project team provides additional management guidance as requested on an individual basis. Co-PD Hoidal continues to offer additional professional development to trial participants in the form of personalized consulting to interpret soil test results from the enrolled tunnels and use these results to develop nutrient management plans. Five field days were held to provide hands-on training to current and aspiring high tunnel farmers in high-priority HT management topics. When asked to rate how much they had learned about the featured topics (rating choices were: "already knew a lot," "nothing," "a little," "some," and "a lot"), 76% of participants' responses indicated that they had learned "some" or "a lot" about the topics. In addition to Dakson Sanon (UMN) and Kevin Fantinatti (UNH), a new M.S. student, Ben Tanner, has joined the project on the UMN team and will be focusing on identifying factors that affect N fixation and the provision of N credits by legume cover crops in HTs. The three graduate students on the project have received training and mentorship from PD Grossman, co-PI Sideman, and co-PI Fernandez to develop skills in protocol development, data management and analysis, laboratory analysis techniques, and public presentation to farmer and academic audiences. Dakson Sanon has been awarded professional development funding from the UMN Applied Plant Sciences graduate program to present results from field trials at the 2025 CANVAS conference in Salt Lake City, UT, and a Fulbright Scholar award through the U.S. Department of State to pursue graduate students from his home country of Haiti How have the results been disseminated to communities of interest? As data continues to accumulate, we are continually updating the farmer-oriented summaries of trial findings to keep our network informed. A preliminary summary of first-year data on establishment and performance of the legume cover crop species options in each rotational timeslot from post-planting surveys was distributed via email to participating farmers in August 2025. A total of 61 farmers have now enrolled in the field trials, some for multiple cover cropping timeslots, and at least 52 have planted legume cover crop plots in their high tunnels using seed, instructions, and 1:1 consultations provided by our team. Farmers who provided biomass samples also received an estimate of the N credit provided by their cover crops. This adds a significant pool of experience with legume cover cropping to the organic high tunnel farming communities in the Midwest and Northeast. Information about the project was published on September 12, 2025 in the University of Minnesota student newspaper (MN Daily). The article, "Researchers seek alternatives to traditional fertilizers," was distributed electronically to 75,000 UMN students. What do you plan to do during the next reporting period to accomplish the goals?During the upcoming Y3 reporting period, we will continue to work towards our three project objectives, with the overarching goal of increasing cover crop adoption to improve resilience and soil health in organic high tunnel production. Across all activities, we will work to engage and serve emerging farmers. Key activities will include: Objective 1: Continue field trials. Establish research station trials and on-farm trials for the spring and summer 2026 and planting timeslots. For on-farm trials, we will maintain robust recruitment of established high tunnel growers, while expanding promotion of this participation opportunity to emerging farmers, through outreach to our soil health train-the-trainer cohort and contacts in emerging farm organizations and the MN Department of Agriculture's Emerging Farmers Office. Complete data collection for the second season of research station and on-farm trials: research team will travel to stations and focus farms to collect soil and biomass samples, and will administer surveys to farmers. A biomass collection and shipping kit has been developed for the low-barrier farms, which we anticipate will increase the proportion of farmers returning self-collected biomass samples. Host field tours and outreach events Work with Fond du Lac Tribal and Community College and other participating farms to develop on-farm field days. We had planned a presentation station on HT soil fertility challenges and the use of legume cover crops for the NCROC annual open house, which draws an audience of farmers, Master Gardeners (peer educators), and community members. However, the open house was cancelled for 2025 due to funding and staffing disruptions. If the event returns in 2026, we will present there; otherwise, we plan to organize a standalone outreach day at the station. Co-PI Sideman is proposing a session on HT cover cropping for the 2026 New England Fruit and Vegetable Conference in December 2026. Present preliminary research findings Expanded preliminary results, including nitrate availability following termination of fall-planted cover crops, will be presented at the participant webinars scheduled for October 28-29 2025, and disseminated to our full contact list (160 farmers). Three farmers have agreed to co-present, and attendees will have the opportunity to share successes and challenges with other growers. Graduate student Dakson Sanon has submitted an accepted poster abstract and will be presenting preliminary results from the fall cover cropping timeslot to an academic and agricultural professional audience at the 2025 CANVAS conference. Objective 2: Continue interviews with case study participants Develop preliminary case study reports Pilot presentation of one or more case studies in the 2026 HT production course (Objective 3), and collect student feedback to use for curriculum refinement Objective 3: Deliver the 2026 High Tunnel Production course, including online content and hands-on activities at research stations and/or farm sites. Because interest in the course was so strong in 2025, instructors Hoidal and Heimark raised the enrollment cap to 30 for next year's class.

Impacts
What was accomplished under these goals? This project aims to address documented challenges to soil health and sustainability in organic high tunnel vegetable production, which include accumulation of excessive P in HT soils and loss of productivity over time. Use of high-N, low-P carbon-based inputs is needed to maintain fertility and soil health in HTs, a goal that research by our team and others suggests could be met via the use of legume cover crops. Many organic HT growers are familiar with cover crops in their field production systems; however, as adoption of HT production is relatively new for many growers, on-farm research is needed to build a knowledge base and set of recommendations for how cover cropping practices can be adapted to HT environments, especially concrete management practices that will allow farmers to time cover crop use with existing fallow periods. An integral part of the adoption of new technologies or management systems is the development of farmers' practical knowledge of the associated costs and benefits, which this project seeks to address through development and delivery of economic case studies and educational curriculum on high tunnel cover crop use. The people impacted by this work include both established high tunnel producers and those who are beginning or aspiring to high tunnel production, who are gaining hands-on experience and educational and networking opportunities related to cover cropping and HT production more broadly. HT production is a potentially valuable enterprise for beginning and low-income farmers, and an important focus of this project is ensuring that benefits of our research findings and educational outputs will be shared with emerging farmers, those who have faced historical disadvantages in accessing resources for building successful farming enterprises. The incorporation of cover crops into HT systems is a particularly valuable practice for low-resource growers, as it enables decreased reliance on manure and purchased fertilizers, reducing the cash expenditures required for production. Objective 1: Improve our understanding of agronomic trade-offs associated with cover crop integration across a range of working organic farms by evaluating best-bet cover crop options for commonly available rotational time slots. Activities and results:Research station ("mother") trials: Replicated cover crop trial plots for the summer and fall 2025 timeslots were planted at the UMN North Central Research and Outreach Center in Grand Rapids, MN. Fall timeslot plots were also planted in the certified organic on-campus tunnel in St. Paul, MN.On-farm ("baby") trials:Farmers enrolled in the first field trial year provided data as outlined for each participation level of the trial: focus farms (FF) provided cover crop biomass samples, soil samples at multiple sampling timepoints, and yield measurements from following crops, while low-barrier (LB) farms provided a farmer-collected soil sample. The field teams in Minnesota and New Hampshire collected and analyzed soil and cover crop biomass samples from focus farms in their respective regions. Additional data on farmer practices, experiences, and stand establishment outcomes were collected through a post-planting survey.In summer 2025, farmers began planting cover crop plots and collecting soil samples for the second trial year, which will continue through project Y3. Recruitment took place through the project's contact list, farmer listservs, emerging farmer contact lists, and in-person invitation at field days. A total of 67 farmers have now enrolled in on-farm field trials, and this is expected to grow as we complete recruitment for the upcoming spring and summer timeslots. Several farmers from the first trial year have re-enrolled. Outcomes:Soil and biomass samples were collected from fall-planted (8 focus farms (FF), 21 low-barrier farms(LB), and UMN NCROC) spring-planted (3 FF, 10 LB) and summer-planted (3 FF, 9 LB, and NCROC) legume cover crops. Cover crop plantings for the second year of the fall/overwinter rotational timeslot are in progress on enrolled farms (8 FF, 8 LB). Analysis of preliminary data indicates that fall-planted legume cover crops can contribute substantial quantities of biomass and nitrogen to high tunnel soils. Austrian winter pea produced the highest average biomass in the fall planted cover crop trial at 1243 kg/ha, followed by hairy vetch, which was more variable but averaged 1022 kg/ha. On working farms, soil nitrate was lower at cover crop termination in cover cropped plots than in the co-cover control. However, nitrate increased relative to the control as the cover crop residues decomposed, such that nitrate levels averaged higher than control by six weeks after vegetable planting-a time of high nitrogen demand for many crops. In our replicated research station trial in Grand Rapids, MN, both Austrian winter pea and hairy vetch increased nitrate availability in the soil at the time that the subsequent pepper crop was planted. Interestingly, this was the case even though Austrian winter pea did not survive the winter, suggesting that decomposing fall biomass may have been providing a nitrogen benefit. Impacts: Farmers' experiences revealed both successful practices and potential challenges for HT cover cropping. Of 26 farmers who gave post-planting feedback on their overall experiences, 23 said that they would use cover crops in their high tunnels again, 2 were unsure, and only one said that they would not use cover crops again. Several farmers reported that their cover crops were partially or completely destroyed by high tunnel pests, indicating a need for guidance on how to exclude rabbits and rodents from high tunnels overwinter. Objective 2: Create educational case studies to help farmers and students make decisions about cover crop integration in tunnels with an emphasis on economic outcomes. Results: Four farmers were identified and interviewed to compile first-year cover cropping observations that will be used in educational case studies. Two of the farmers are from Minnesota and elected to plant fall legume-mix cover crops. The other two farmers are from New Hampshire where one planted cover crops during the fall and the other during the summer. The growers were interviewed twice - immediately after cover crop planting and again after termination. Outcomes: First year grower observations about cover crop labor costs and equipment needs were compiled and compared along with additional observations about perceived vs. actual cover cropping benefits. Impacts: A number of challenges were identified during the interviews, namely seed establishment, irrigation, pests, and spring termination. Challenges were consistent across farms that elected to plant fall cover crops. These results were used to inform the Y2 survey of all participating farms with the intention of learning whether the results observed on the case study farms were experienced universally by time slot, seed mix and geographic location. Objective 3: Meet farmer demand for education and networking opportunities for high tunnel producers through development of an annual course emphasizing organic HT management. Results: 25 farmers enrolled in the 9-week HT course in spring 2025, which was taught synchronously online via 1.5 hr weekly Zoom sessions. Topics covered included crop planning, irrigation, fertility, pest management, and food safety. The materials were housed in Canvas LMS (learning management system) (homework, recorded lessons, etc). Outcomes: Students in the HT course also had the opportunity to network with other new and aspiring HT farmers, and to meet and ask questions of experienced HT growers through five field days that took place throughout the 2025 growing season. Impacts: 100% of students who completed a course evaluation reported that the course improved their profitability as well as their production methods.

Publications

• Type: Conference Papers and Presentations Status: Submitted Year Published: 2025 Citation: Pending: Sanon, D., Grossman, J. M., Fernandez, A. L., Sideman, R. G., Tanner, B., Sooksa-nguan, T., & Fantinatti, K. (2025) Legume Cover Crops As a Soil Fertility and Productivity Management Strategy in Organic High Tunnel Farming Systems. Poster presentation at CANVAS conference, Nov 9-13 2025, Salt Lake City, UT.

Progress 09/15/23 to 09/14/24

Outputs
Target Audience:Our long-term goal is to increase adoption among organic HT growers of the agroecological practice of cover cropping to improve productivity, environmental outcomes, and resilience associated with intensive HT production environments. As the use of legume cover crops has potential to reduce farmers' need for purchased manure-based fertilizers in their high tunnels, adoption of cover crops may be particularly valuable for farmers with limited resources. This project includes a focus on education and outreach for emerging farmers, including immigrant farmers, farmers of color, and others who face barriers to traditional farmer support programs. These farmers form a crucial and growing segment of the local food system and the organic vegetable production community in the Midwest and Northeast regions. In particular, emerging farm communities in our regions include many immigrant growers who bring strong farming knowledge from their previous countries, and are actively seeking to adapt their practices to succeed in a northern US context. Our project represents part of a broader effort to connect these farmers with public resources and programs including University Extension support and state and federal programs for farmer education and financial support. For most of Y1, our focus was on information gathering and trial preparation. We collected input through individual conversations with experienced organic HT farmers, and focus groups with 18 farmer participants, conducted online and in person. Perspectives in the focus groups were well balanced between emerging farmers and those with more traditional Midwest and Northeast US farming backgrounds. In the second half of the project year, we began robust farmer recruitment for on-farm trials and farmer evaluation of 'best bet' cover crops, which resulted in 78 farmers filling out an initial interest form, 15 attending informational webinars, and 35 enrolling in on-farm trial research efforts which will continue into Y2. Our initial goal for farmer participation in field trials Y1 was 35 farms across the Upper Midwest and New England. With 35 farmers enrolled in the trials so far, we have met that goal and are on track to exceed it when recruitment for Y1 spring and summer plantings is complete. Because recruitment was taking place concurrently with the refinement of experimental treatments and trial instructions, our initial round of on-farm trial recruitment has been more heavily weighted toward mainstream and established organic farm communication networks, in order to ensure that we connect with farmers who are certified organic, comfortable communicating with the research team, and are already producing vegetables in existing high tunnels. As trial procedures are established and any potential points of confusion in our farmer instructions are clarified, we will intensify recruiting within emerging farm communities through contacts at state and federal agencies and local organizations. While we do not have detailed demographic data on trial enrollees, we are aware that our initial group also contains several beginning farmers. One emerging farmer enrollee has faced delays in the construction of a planned high tunnel, and has deferred participation to a later timeslot. In addition to direct communication with farmers, our Y1 activities included presentation of HT soil health information and trial goals at a research station open house event, where we engaged an estimated 75 visitors including a mix of farmers, gardeners, and interested members of the public. As education and outreach activities accelerate in the coming project years, engagement with emerging farmers will be central. Our team is leading an ongoing project, initially funded with an internal UMN grant and now continuing with support from the SARE-PDP program (Project ENC24-237), to provide train-the-trainer programming on soil health management practices to a cohort of organization personnel and farmer mentors who provide technical assistance emerging farmers. Practices and findings from this trial will be incorporated into training for the cohort, and we will also tap this network for field trial (Objective 1) and HT production course (Objective 3) recruitment. Changes/Problems:Responses from our focus group participants revealed significant interest among high tunnel farmers in using cover crops in a midsummer rotational timeslot, in tunnels where the primary cash crops are cool-season vegetables such as winter spinach, or tunnels that are being fallowed for a season. Based on this feedback, we have added a third, summer-planted timing option to the on-farm "baby" trials. Because space and infrastructure constraints in the research station replicated "mother" trials do not allow us to plant three timing treatments, we have decided to include the summer timeslot rather than the originally planned early spring timeslot in the mother trials. This decision was further reinforced by farmer communications during the fall on-farm planting period: several farmers who had planned to plant fall cover crops notified us that, due to warm weather that extended the harvest of summer vegetables, they would not have their high tunnel beds cleared within the recommended planting window for fall cover crops. These farmers have agreed to join the early spring planting timeslot instead. This experience suggests to the research team that fall and early spring cover crop plantings are options that may both be suited to similar warm-season vegetable cropping systems, and farmers who adopt these practices are likely to be deciding between these planting timings on an ad hoc basis based on season-specific conditions; as opposed to a summer cover crop planting window, which represents a more distinct option for rotations focused on cool-season vegetables or farmers with multiple tunnels. Because Co-PD Heimark has moved to a new position with Renewing the Countryside (RTC), the 2025 and 2026 high tunnel producer courses will be offered through a RTC/UMN Extension collaboration. The curriculum will remain as proposed; planning is underway to transfer the subcontract funding and course materials. This is anticipated to improve recruitment for the course, because participants will not need to register for college credit (which was a barrier in similar courses offered previously). What opportunities for training and professional development has the project provided?Training and professional development opportunities offered by this project in Y1 have included: Direct training of farmers in high tunnel cover cropping options and methods. Through webinars, our team provided education to 15 farmers on common soil health challenges in high tunnels including P and salt accumulation, and legume cover crop species and timing options for managing HT soil fertility. Additionally, farmers have gained direct, hands-on experience with cover crop adoption through our on-farm field trials. We developed detailed instructions and provided seed to trial participants, resulting in 30 farmers planting cover crops in their HTs, most for the first time. Co-PD Hoidal is offering additional professional development to trial participants in the form of personalized consulting to interpret soil test results from the enrolled tunnels and use these results to develop nutrient management plans. Our team has provided information to our emerging farm soil health train-the-trainer cohort (described above) about research goals and the process of participating in the research project. Trial enrollment by cohort members has so far been limited, but more outreach to these key educators and the farmers they serve is planned for the upcoming enrollment periods. Two graduate students on the project have received education on cold-climate high tunnel production systems and training in research design, high tunnel operation, and cover crop establishment and management. Through work with research station and on-farm soil samples, these students are continuing to develop professional skills in collaborative project management, sampling methods, laboratory analysis, and data management. An additional, more senior, graduate student has worked with the team to train the newer members and gain experience in mentorship and project management. How have the results been disseminated to communities of interest?As research trials have just begun for this project, we have not yet developed scientific findings for dissemination. However, we have taken opportunities to engage current and aspiring high tunnel growers and members of the public. 18 farmers participated in focus groups to discuss their experience, interests, and ideas related to using legume cover crops in high tunnels. Recruitment for a focus group via handouts and word of mouth at the Marbleseed organic farming conference was successful at reaching farmers who have not previously participated in academic research, resulting in a focus group composed entirely of immigrant and/or women farmers. We have also recruited for focus groups and field trials through farmer-focused listservs, and announcements through our team's networks. 15 farmers participated in informational webinars about the high tunnel cover crop field trials, in which we presented previous findings from our team and other researchers about common soil health challenges in high tunnels, and the potential of legume cover crops to support crop production and sustainability in high tunnel vegetable systems. 35 farmers enrolled in the field trials for 2025-26, including 30 who planted cover crops in the fall timeslot using seed and instructions provided by our team. This adds a significant pool of experience with legume cover cropping to the organic high tunnel farming communities in the Midwest and Northeast. Information about organic soil health in high tunnels, and the background and objectives of this trial, was presented to approximately 75 attendees at the UMN NCROC Open House. Although formal demographic information was not collected, attendees who visited our education station included many local visitors and families who expressed that soil research was new to them. Anecdotally, these included people growing vegetables at large garden/small farm scales on the border between household and commercial production, which in our experience represents an important and often under-served segment of fresh vegetable producers. What do you plan to do during the next reporting period to accomplish the goals?During the upcoming Y2 reporting period, we will continue to work towards our three project objectives, with the overarching goal of increasing cover crop adoption to improve resilience and soil health in organic high tunnel production. Across all activities, we will work to engage and serve emerging farmers. Key activities will include: Objective 1: Continue field trials. Establish research station trials and on-farm trials for the spring and summer 2025 and fall 2026 planting timeslots. For on-farm trials, we will maintain robust recruitment of established high tunnel growers, while expanding promotion of this participation opportunity to emerging farmers, through outreach to our soil health train-the-trainer cohort and contacts in emerging farm organizations and the MN Department of Agriculture's Emerging Farmers Office. Complete data collection for Y1 research station and on-farm trials: research team will travel to stations and focus farms to collect soil and biomass samples, and will design and administer biomass collection protocols and outcome surveys for low-barrier farms. Host field tours and outreach events Work with participating farms to develop on-farm field days. Work with organizational partners to identify opportunities for project findings, case studies, and farmer experiences to be incorporated into partners' planned educational programming, such as UMN Extension's Organic Field School, the Sustainable Farming Association of Minnesota's annual conference, and the UMN North Central Research and Outreach Center's annual open house. Objective 2: Recruit case study participants from list of already identified prospects Conduct interviews, and develop case study reports and pilot curriculum Pilot presentation of case study curriculum in the 2025 HT production course (Objective 3), and collect student feedback to use for curriculum refinement Objective 3: Deliver the 2025 High Tunnel Production course, including online content and hands-on activities at research stations and/or farm sites. All objectives: Convene farmer advisory group to present preliminary findings, discuss implications for farmer practices, and identify engagement and outreach opportunities. Five experienced organic HT growers have agreed to participate in our farmer advisory group. Original plans called for this group to be convened in Y1; however, as questions were developed for the farmer focus groups, we felt that the input that we had planned to request from the advisory group in their initial meeting was covered by what we had already asked them during individual conversations and the input that we were collecting from a larger number of farmers in the focus groups, so in order to ensure that we were making best use of the advisory farmers' limited time, we made the decision to postpone the first meeting of the advisory group to Y2.

Impacts
What was accomplished under these goals? This project aims to address documented challenges to soil health and sustainability in organic high tunnel vegetable production, which include accumulation of excessive P levels in HT soils and loss of productivity over time. Use of high-N, low-P carbon-based inputs is needed to maintain fertility and soil health in HTs, a goal that research by our team and others suggests could be met via the use of legume cover crops. Many organic HT growers are familiar with cover crops in their field production systems; however, as adoption of HT production is relatively new for many growers, advanced on-farm research is needed to build an established knowledge base and set of recommendations for how cover cropping practices can be adapted to individual farmer's HT environments, especially concrete management practices that will allow them to time cover crop use with existing fallow periods so cash crop productivity will not be not greatly affected. An integral part of the adoption of new technologies or management systems is the development of farmers' practical knowledge of the associated costs and benefits, which this project seeks to address through development and delivery of economic case studies and educational curriculum on high tunnel cover crop use. The people impacted by this work will include both established high tunnel producers and those who are beginning or aspiring to high tunnel production, who will gain hands-on experience and educational and networking opportunities related to cover cropping and HT production more broadly. HT production is a potentially valuable enterprise for beginning and low-income farmers, and an important focus of this project is ensuring that benefits of our research findings and educational outputs will be shared with emerging farmers, those who have faced historical disadvantages in accessing resources for building successful farming enterprises. The incorporation of cover crops into HT systems is a particularly valuable practice for low-resource growers, as it enables decreased reliance on manure and purchased fertilizers, reducing the cash expenditures required for production. Objective 1: Improve our understanding of agronomic trade-offs associated with cover crop integration across a range of working organic farms by evaluating best-bet cover crop options for commonly available rotational time slots. Results: Cover crop trial plantings for a fall/overwinter rotational timeslot were successfully established at two research sites and 30 farms. Farmer engagement with the first year of the project provided clear evidence for high tunnel farmers' interest in this objective and need for information and hands-on experience, with 78 farmers filling out an initial interest form, 18 participating in focus groups, 15 attending informational webinars, and 35 enrolling in on-farm trial research efforts which will continue into Y2. Two graduate students joined the project: Dakson Sanon, a PhD Fulbright student at the UMN advised by PD Grossman, and Kevin Fontana Fantinatti, a M.S. student at UNH advised by co-PD Sideman. The graduate students will take a leading role in field trial operations and data collection. Outcomes: Based on farmer input given in our focus groups, we refined our experimental treatments to better reflect farmers' knowledge and rotation practices. Some farmers expressed interest in cover cropping in a midsummer timing window, to fit into vegetable production schedules that focused on cool-season or overwinter crops such as spinach, or as a fallow option for tunnels that were being rotated out of production. We also added an additional "extended menu" option of bell bean (fava) to the spring and summer cover cropping timeslots. At the end of Y1, 30 farmers planted cover crops in the fall timeslot, for which we provided seed and instructions. Impacts: Farmers attending focus groups and webinars increased knowledge of which species are being used in high tunnels through sharing of information among those in their group. Farmers participating in the field trials gained hands-on experience with high tunnel cover crop planting. Objective 2: Create educational case studies to help farmers and students make decisions about cover crop integration in tunnels with an emphasis on economic outcomes. Results: A case study questionnaire was developed using research methods outlined by Robert Yin (1994). The questionnaire was distributed for review and comment to all team members and further refined based on their recommendations. Case study recruitment materials were also developed and shared with team members working with the on-farm trial participants. Team members were asked to help identify two growers from the Midwest region and two growers from the NE region who met case study qualifications to participate in the case studies. Outcomes: Four growers were identified from field trials. Recruitment will occur in Year 2. Impacts: No impacts at this time. Objective 3: Meet farmer demand for education and networking opportunities for high tunnel producers through development of an annual course emphasizing organic HT management. Results: In 2022 and 2023 a hybrid and online High Tunnel course was taught by co-PD Heimark at Central Lakes College, independent from this project. The two previous years of teaching informed how Heimark is shaping this project's iteration of the course in many ways. In 2022, the course featured a high tunnel host site on CLC's campus in which students could learn about and practice concepts learned in the online modules. Maintenance and harvest data was also collected throughout the year and presented on the last day of the course. In 2023, the host site high tunnel was not available which was a cost savings but students were not able to experience and practice concepts learned in the course. During the growing season of 2024, Erik helped 2 farmers navigate their way through getting an NRCS EQIP grant. Outcomes: The course was far better attended when taught entirely online during the "off-season" (Nov. through April) for farmers in 2023. However, the hands-on educational aspects provided by the hybrid course in 2022 were missed as well as the data collected on harvests at the host site. The budget for 2023 was more reasonable without the staff and repairs and maintenance required for the host site. The data collected from 2022 was presented in the 2023 course as well as harvest and financial data Heimark collected on his own farm's high tunnel. This preserved some of the education pieces but the visceral experience of working in a high tunnel was lacking for the students. Additionally, Heimark learned from working with 2 farmers on a USDA EQIP grant that farmers need more education selecting a high tunnel suited for their operation as well as the logistics and costs of shipping and installation of the high tunnel, particularly the labor requirements. Impacts: Co-PD Heimark plans to teach the course using an online delivery method during the off-season and supplement this education with 3 to 4 field days on high tunnel growing farms around the state during the growing season. This way, students will be able to experience first-hand how several different farms manage their high tunnels and take part in training activities such as tomato pruning, irrigation installation and soil testing. This will also give a larger perspective to students instead of just the experience of a single host site high tunnel. Field Day host farms will also be asked to present on some of their harvest and financial data for their farms. A full day of the course has been devoted to learning about selecting a high tunnel, the various component parts to consider and the logistics of how to receive and install a high tunnel on your farm. A local expert on high tunnel construction will also be featured as a guest speaker during the course and perhaps host one of the field days.

Publications