Progress report for LNC23-481
Project Information
Weed interference greatly reduces vegetable crop yield, quality, and harvesting efficiency. Many current weed control methods, including plastic mulches, intensive cultivation, and herbicide applications, can have adverse impacts on the environment. Indiana small farm operators have expressed an interest in adopting additional, non-chemical weed control tactics but often do not know where to start. Many beginning farmers, for example, have questions that can be answered by experienced peer-farmers or by simple on-farm experiments. We propose a grower-directed outreach/demonstration project that includes on-farm research/demonstration, the development of a learning community, and farmer-to-farmer education. Grower-collaborator research questions will guide weed management treatments. On-farm research will consist of a full set of treatments deployed at the Purdue Student Farm in a randomized complete block design and a subset of treatments on grower-collaborator farms. Grower-collaborators and Purdue scientists will learn from more experienced small-scale farmers, other farmers testing the same weed control method, and the broader community of farmers engaged in this project. Results, including trial and observational data, as well as first-hand experiences and recommendations from grower-collaborators, will be shared with small farm operators throughout the state and North Central Region.
Objectives:
-Conduct grower-directed research with underutilized weed management strategies.
-Create a learning community where small farm operator-collaborators can share their experiences with and learn from one another.
-Promote farmer-to-farmer education by giving grower-collaborators a platform to share their results with small farm operators within Indiana and the North Central Region.
Learning Outcomes:
-Increased knowledge of non-chemical, reduced-tillage weed control tactics.
-Increased awareness of the importance of on-farm experimentation.
Action Outcomes:
-Increased engagement of small farm operators across the state.
-Adoption of non-herbicide, reduced-tillage methods of weed management that improve weed control, decrease weeding inputs, and improve their farms’ sustainability.
Background, Rationale and Need
About Small Indiana Vegetable Farms:
From a 2012 survey of 89 Indiana vegetable farmers, Torres and Marshall (2017a) reported that 86% met the USDA definition of “small farm” (less than $250,000 in sales/year). Relative to large farms, small farm operators were more likely to own a greater percentage of the land they farm, rely more on family labor, and sell their products closer to the farm (average of 12 miles from the farm) and directly to the consumer at the farm (74%) or farmers markets (63%). Small farms were also far more likely to produce vegetables organically, whether certified or noncertified. Following a survey of 207 Indiana urban farmers, Shoaf and Ingwell (2023b) reported that 86% of urban farmers in Indiana grew vegetables with 76% growing on less than one acre.
About Small Indiana Vegetable Farm Operators:
Torres and Marshall (2017b) reported that 29 to 35% of small vegetable farms in Indiana were owned by women, compared to only 8% of large vegetable farms in the state. Small farm operators had fewer years of farming experience (22 years, on average) than large farm operators (45 years, on average). The source of information shown to be most useful to Indiana vegetable farmers, regardless of size, was other farmers (97%), followed by Purdue Extension (71%), and grower associations (54%). On average, Indiana vegetable farmers spent 46 hours per week working for their farm business, however, depending on farm size 27 to 67% reported farming only part-time. Shoaf and Ingwell (2023a) showed that 61% of urban farmers identified as female, 3% identified as Hispanic, and 13% identified as Black/African American or non-white. They also showed that 62% of urban farmers were employed outside of their farm and 46% worked full-time at off-farm jobs.
In their survey of Indiana urban farmers, Shoaf and Ingwell (2023b) found that weeds were among the top challenges and were the second most important topic they wanted to learn more about. Furthermore, 87% of respondents reported they wanted to attend Extension programs, 46% would like to participate in on-farm collaborative research, and 35% would be willing to help plan local Extension programs and host trainings or tours. Sixty-eight percent of respondents rely on local Purdue Extension Educators for information, and 63% relied on other farmers.
What Does This Mean?
By and large Indiana small farms are a part of their communities- providing nutritious vegetables directly to consumers. Compared to larger farm operators, they own proportionately more of the land they farm and are operated by a greater proportion of women, persons of color, and by individuals with relatively less farming experience. Generally, organic practices are important to their production ideology. They seek information from fellow farmers and Extension and are willing to participate in on-farm research. In this way, small farm operators have a genuine vested interest in economic, environmental, and social sustainability.
A Community Approach to Extension:
We recognize that most weed management research conducted by the Land Grant universities has been devoted to large acreage commodity crops. The standard methodology has been to identify needs, conduct research, and tell growers what has been found. We do not believe this is the best strategy for small farms.
-The production methods, scale of production, and equipment used on small, diverse farms in Indiana do not lend themselves to a simple scaling down of research methods. Small farms are not just farms with less acreage; they are different from large farms in many important ways, and they present different social, economic and environmental impacts and benefits. Research and Extension must be tailored to small farms and the people who run them.
-In many ways small farm operators have filled the weed management research void and been the drivers behind the innovation in small farm weed management strategies- developing novel methods of weed control. For this reason, farmers have greater expertise than university researchers with many weed management methods. However, not all farmers have the same extent of experience, and even farmers experienced in specific weed management practices would like to learn more. For example, silage tarps are widely used by small farm operators to terminate mowed
cover crops, to manage winter annual weeds and provide quicker access to land in the spring, and to assist with stale seed bed operations. The first-hand experiences of growers with this weed control method greatly outnumber the three peer-reviewed journal articles on the topic (Kubalek et al. 2022). Growers with experience in silage tarping are eager to share their experiences with others and to experiment on their farms to learn more about this method (see letters of support).
-Given the gap in university research for weed management on small farms and the inherent expertise of small farm practitioners, we believe there is synergism in a learn together approach with equal input and that bilateral communication between university and growers provides the greatest potential for impact. Research must be co-produced. Information flows in both directions. We see our role in this project not as an agency delivering wisdom to growers but as a facilitator of co-learning with growers.
Literature Cited:
Arana, J., Meyers, S.L., Cardona Giraldo L.A., Vargas Arroyo, N.B., Rodriguez Baquero,
L.D. (2022) Using black soldier fly larvae composting to reduce weed seed
germination. Proceedings from the 77th Annual Meeting of the North Central Weed
Science Society. 1 p.
Kubalek, R., Granastein D., Collins, D., Miles, C. (2022) Review of tarping and a case
study on small-scale organic farms. HortTechnology 32:119-128.
Mohler, C.L., Teasdale, J.R., DiTommaso A. (2021) Handbook 16: Manage Weeds on
Your Farm: A Guide to Ecological Strategies. SARE. 416 p.
Shoaf, N., Ingwell L. (2023a) Urban Agriculture: Demographics of Indiana’s Urban
Agriculturists. ID-530-W. Purdue Extension: W. Lafayette, IN. 3 p.
Shoaf, N., Ingwell L. (2023b) Urban Agriculture: Opportunities and Challenges for
Indiana’s Urban Agriculturists. ID-531-W. Purdue Extension: W. Lafayette, IN. 5 p.
Torres, A., Marshall M. (2017a) Fruit and Vegetable Farmer Surveys: Characteristics of
Indiana Vegetable Farmers. HO-271-W. Purdue Extension: W. Lafayette, IN. 7 p.
Torres, A., Marshall M. (2017b) Fruit and Vegetable Farmer Surveys: Characteristics of
Indiana Vegetable Farming Operations. HO-270-W. Purdue Extension: W. Lafayette, IN.
6 p.
Research
Weeds can be managed sustainably on small vegetable farms with controls tactics that do rely on excessive cultivation, single use plasticulture, and synthetic herbicides.
Small vegetable farm operators will learn from on-farm research and one another.
We propose a grower-directed, integrated outreach/demonstration project founded on three pillars: grower-directed on-farm research and demonstration, development of a learning community, and farmer-to-farmer learning. (Note: Due to the involvement of human subjects in this project, all procedures will be reviewed by the Purdue Institutional Review Board for approval.)
Recruitment of Grower Participants:
Once the project receives notification of funding, we will renew our recruitment efforts to increase the number and diversity of Indiana small farm participants committed to collaboration. Our goal is to recruit 25 Indiana small farms to participate in on-farm research.
-Recruitment information will be disseminated through three Purdue grower newsletters (Diversified Farming and Food Systems, Vegetable Crops Hotline, and Facts for Fancy Fruit), two Purdue focus groups (Horticulture, Diversified Farming and Food Systems), and through Agriculture and Natural Resources County Educators in all 92 Indiana counties.
-Additional, targeted recruitment will be facilitated by the Purdue Urban Agriculture Specialist, the Indiana SARE Coordinator, and Purdue Horticulture Extension through private mailing lists.
-The Indiana Hoosier Young Farmer Coalition will help with recruitment through their direct e-mailings, social media posts, and classified tab of their website.
-Finally, grower-participants associated with the development of this proposal will reach out to their grower network and recruit additional small farm operators who have an interest in this project.
Establishment of an Advisory Committee:
We will formalize the involvement of farmers and farmer organizations in the oversight of this project by establishing an advisory committee. The committee will include at least equal representation of farmers with non-farmers, with one representative from the Hoosier Young Farmer Coalition. The advisory committee will provide guidance and input on all aspects of the project, including the format, location, and agenda of field days sponsored through this project. On an annual basis, it will evaluate the progress of the project and make recommendations to improve our efforts.
Identification/Confirmation of Grower Interests:
Although farmers and farmer organizations were included in the development of this project, we realize that newly recruited grower-participants will have valuable insight and want to ensure their input is included.
-We will use a mixed-methods research approach to examine farmer perspectives on weed interference, control method preferences, interest in adopting underutilized weed management methods, barriers to adopting new methods, and preferred communication and engagement approaches.
-Semi-structured interviews will be conducted with participating farmers, and these qualitative results will inform the development of a statewide survey instrument to assess farmer needs, barriers, and weed management tactics to be explored.
-This process will help to validate the finalized list of weed management methods explored in this project. It will determine to what extent the farmer collaborators are representative of small farm operators state-wide. It will allow us to modify our approach to address existing barriers to adoption and ensure that we use the most effective means of communication for university-to-farmer and farmer-to-farmer engagement.
-The revised methodology will be shared with the Advisory Committee and attendees of the 2024 Indiana Small Farms Conference (February) to finalize 2024 participants and determine which farms will participate in each weed management method.
Grower-Directed On-Farm Research/Demonstration:
-Through the outreach efforts listed above, grower-collaborators will identify weed management methods they would like to trial on their own small farms, resulting in a set of research questions.
-Grower-collaborators and Purdue University scientists will collaborate to develop a set of treatments required to answer the grower-defined questions.
-A full set of replicated and randomized research treatments will be conducted at the Purdue Student Farm and grower-collaborators will deploy subsets of treatments. On-farm research at the Student Farm will be the subject of a graduate student thesis and will also train undergraduate students in small farm production systems. Grower-collaborators will be encouraged, but not require, to also utilize randomization and replication as space and time allow.
-It is expected that growers will utilize their existing practice on some portion of their farm for the purposes of comparison.
-Grower-collaborators will be supplied with the materials and instructions needed to trial weed management methods on their farm.
-Project staff will be available to assist with the establishment of on-farm grower-collaborator trials.
-Data collection sheets and instructions will be developed to ensure all grower-collaborators are collecting similar metrics for their sites.
Proposed Research and Demonstration (Based on Initial Grower Requests):
Silage tarping: Tarping research at the Purdue Student Farm and with on-farm collaborators will evaluate and demonstrate their use in a stale seedbed. All research at the student farm will utilize a randomized complete block design with four replications. Soil moisture, temperature, and photosynthetically active radiation (light) will be monitored to determine how they differ under each treatment. Hand-weeding time for each treatment will be recorded.
- Initial studies will investigate fall vs. spring-applied tarps prior to transplanting onions. Onions have an open canopy, shallow root system, and tight in-row spacing making them susceptible to high yield loss due to weed interference and rendering mechanical weed control difficult and time-consuming. Treatments will include fall-made and tarped beds, spring-made and tarped beds, and spring-made non-tarped beds. Weed counts and visual estimates of weed control will be recorded every other week. Onion number and weight will be recorded at harvest.
- Tarping and fabric. We propose to investigate the potential additive or synergistic benefits of combining silage tarps with woven fabric soil barriers. Beds will be prepared in the spring. Treatments will consist of tarping alone, tarping followed by woven fabric, and woven fabric and tarping applied at the same time. We hypothesize that when applied simultaneously after bed formation, fabric plus tarping will provide the greatest weed control with greater efficiency. Once the tarp is removed, this treatment should be able to be planted with no additional steps required. The beds will be transplanted with tomatoes. Weed counts and visual estimates of weed control will be recorded every other week. Tomato yield will be recorded.
- Use of tarps for early season weed control: For crops that require weeks to germinate or emerge, tarps can be applied to beds after planting and removed at crop emergence. Some small vegetable farm operators have used this method for carrots. We will apply tarps to prepared beds, remove them after three weeks, plant carrots and replace the tarps for 5, 10, or 15 days to determine the influence on weed control and carrot crop stand. A follow-up study will also include flame weeding to control emerged weeds prior to carrot emergence.
Woven fabric: To test address grower concerns related to woven fabric soil barrier quality and durability, we will purchase the most commonly used fabrics marketed to small farms and those available locally at farm/hardware stores. Fabrics will be laid over prepared planting beds and evaluated for ease of use, wear over time, amenability to planting holes, effect on soil temperature prior to and after transplanting, light interception (% of light blocked from reaching the soil surface), and weed suppression.
Black soldier fly larvae (BSFL) composting: Composting bins/piles will be treated with BSFL larvae. The rate of decomposition of compost contents will be recorded. Compost temperature will be recorded weekly and finished compost will be analyzed for moisture, density, organic matter, nutrient content, electrical conductivity, and carbon-to-nitrogen ratio. A subsample of compost will be placed into a plastic flat with potting media and watered to determine the amount and type of weed seeds that germinate. Due to the ability to of the flies to move to adjacent compost bins/piles, replication on farm will be difficult. Results will be compared to composts from other small farms participating in the project, but not on the BSFL objective. All composts analysis results will be shared with the farm they came from.
Development of a Learning Community & Farmer-to-Farmer Learning:
Peer-to-peer learning has been shown to be an effective way to increase networking opportunities among farmers, transfer knowledge, and create a shared community for support when adopting new techniques and learning new systems. The goal is to create a supportive community and instigate innovation for small-scale farming systems.
-Grower-collaborators with similar weed management interests will be identified and grouped to develop a network of collaborators. For example, growers who express an interest in black soldier fly composting will be networked to increase communication.
-Efforts will be made to include small farm operators with various levels of experience (beginning vs. established), different growing environments (urban vs. peri-urban vs. rural), and scale of operation.
-All grower-collaborators will meet together with the project team twice a year to discuss their experiences and findings and to refine methods for future years. The venue (in-person, online) and topics of discussion for these meetings will be defined by the grower collaborators and facilitated by the Project Coordinator.
-Grower-collaborators and Purdue researchers will participate in roundtable and/or panel discussion field days and educational events to share the findings of the group with the other small farm operators in Indiana.
-Similarly, on-camera grower interviews will be used to communicate the findings and first-hand experiences with other small farm operators across the North Central Region.
2024
In order to recruit farmers and members of the advisory council, Purdue University required that the investigators apply for and receive IRB approval for research with human subjects. The IRB approval process required multiple iterations between the investigators and Purdue IRB representatives. This process was not completed in 2024 and resulted in delayed farmer recruitment and advisory council formation until 2025. In the absence of an formal advisory council, research pursued at the Purdue Student Farm was based on grower input acquired during the initial preparation of this proposal.
Purdue Student Farm research conducted in association with this project included weed management of small-scale transplanted bulbing onions using clear tarps, silage tarps, shallow cultivation, and flame-weeding compared with one typical synthetic and one organic herbicide. These pre-transplanting control tactics were combined with one of two in-season weeding methods (a tine weeder or a "Magic" weeder) followed by hand-weeding. Findings of this graduate student lead project suggest that applying a clear tarp to prepared onion beds in the early spring heated soil and encouraged the germination of summer annual weeds. These weeds were most effectively controlled by a subsequent silage tarp application, creating an optimal stale seedbed for onions and reducing the time required to hand-weed plots later in the season. Flame-weeding was also acceptable. However, shallow cultivation with a power harrow and the organic herbicide (caprylic and capric acid) controls provided less weed control than silage tarping or flame-weeding. The synthetic herbicide control treatment (glyphosate) resulted in excellent at-planting weed control but did result in onion crop stunting. The "Magic" weeder provided more efficient post-transplanting weed control than the tine harrow.
A second graduate student lead study explored the use of black soldier fly compost tea for pre-emergence weed suppression. Black soldier fly larvae were reared in a Purdue University greenhouse of a food waste diet. The resulting compost (frass) was dried then used to create a 1:5 compost tea consisting of 1 g of compost to 5 ml of water. This initial concentration of black soldier fly compost tea was placed into petri dishes along with 25 seeds each of velvetleaf, barnyardgrass, and redroot pigweed and placed in a growth chamber. While all weed species germinated in a deionized water control treatment, none germinated in the compost tea treatment. Follow-up studies were conducted to determine the effective dose of black soldier compost tea for each species. Results from this study were recorded in 2025.
Education
Graduate student training: Research associated with this project that is conducted at the Purdue student farm and on campus is the thesis subject of graduate students. The students develop protocols, conduct research, and report their findings to stakeholders and peer scientists. In this way, students learn by doing.
Grower education: Grower education has occurred by round table discussion at the Indiana Small Farms Conference, at presentations made at field days and webinars, and through printed newsletter articles.
Project Activities
Educational & Outreach Activities
Participation summary:
2024
Newsletter articles documenting research from this project:
1.) Silage Tarps for Small Farm Weed Management | Purdue University Vegetable Crops Hotline
2.) Weed Management Strategies for Vegetable Farms | Purdue University Vegetable Crops Hotline
Field days demonstrating research from this project:
1.) Tarps, fire, and cultivation- weed management updates and demonstrations. Purdue Small Farm Education Field Day. July 25, 2024 (West Lafayette, IN).
2.) Silage tarping demo. Midwest Mechanical Weed Control Field Day. Sept. 11, 2024 (Lafayette, IN).
Webinars/Presentations/Talks:
1.) Cover crops for weed management in vegetables. Midwest Cover Crops Council Annual Meeting. Feb. 14, 2024 (Indianapolis, IN).
2.) Lightning round research updates from Purdue specialists (co-presented with Maynard E, Langenhoven P, Guan W). Indiana Small Farms Conference. Feb. 29, 2024 (Danville, IN).
3.) Using silage tarps for weed control in small-scale farming (presented by graduate students Cerritos J, Corado C). Urban Soil Health Program- Urban Updates Meeting. June 13, 2024 (webinar).