Progress report for LNC23-488
Project Information
Sustainable root-zone management for organic vegetable production in containers
Vegetable production in protected culture is increasing rapidly along with increasing demand for local food among US consumers. USDA has approved organic certification for crops grown in soilless substrates. While this provides a plethora of opportunities, soilless substrates and their management are optimized for synthetic fertilizers. As soilless culture has only recently been accepted as an option for organic production, little research has been done on organic fertilizer options for this type of growing system. The overall aim of the proposed project is to identify the soilless substrates that offer optimum root growth and development with the use of liquid organic fertilizers in containerized production. We will evaluate crop yield and quality along with disease suppression when crops are grown with multiple soilless substrates and organic fertilizers. We will identify the interaction between soilless substrates and organic fertilizers in containerized production. On-farm trials will engage growers and increase the applicability of results to resource availability in farms. The results will provide specific guidelines for limited-resource and beginner producers in adopting sustainable soilless substrates and organic fertilizers for vegetable production under protected culture.
When growers employ container production successfully, they limit their exposure to well-known risks associated with soil-based production while simultaneously becoming more efficient and productive. This will reduce effort, expenses, and complexities associated with organic crop production. They will be able to source materials based on local availability and sustainability to minimize the impact on both business and the environment. With the limitations to field crop production during colder months, protected culture growers will successfully capture the off-season organic market, which relies heavily on imports from Mexico and Canada. Protected culture and organic production offer sound business opportunities that should be both profitable and environmentally sustainable for the next generation; however, many start-ups fail due to lack of education. We will follow this research with a multi-pronged approach to disseminate project outcomes to both current and future farmers with the expectation of increasing farm profitability and sustainability.
The overall aim of the project is to identify OMRI-approved soilless substrates that offer optimum root zone environment with the use of OMRI-approved liquid organic fertilizers.
As action outcomes we will evaluate the influence of organic liquid fertilizers on yield, market quality, root health, plant nutrients, and phytochemical properties of tomatoes and cucumbers grown using multiple soilless substrates in containers. Through a combination of on-farm trials and a multi-pronged outreach program, the results of this project will be disseminated with the current and future vegetable crop farmers to bolster adoption and the success rate of these more sustainable practices.
The project will identify soilless substrates that offer optimum root growth and development with the use of liquid organic fertilizers in containerized production. Outcomes will enable farmers to source materials based on local availability and sustainability.
Many vegetable growers increase their income by adopting value-added organic production. Containerized production is common when growing in protected culture as it allows better control over plant growth and avoidance of many well-known soil-borne diseases. We will introduce substrate and fertilizer management strategies for organic vegetable production in containers, which will help producers growing in a range of environments from high tunnels and greenhouses to indoor farms to adopt organic and more sustainable production practices.
Adoption of containerized organic production methods will reduce the effort required to mitigate challenges of soil-based organic production. This will allow growers to expand into value-added markets while simultaneously reducing their environmental impact. Our extension activities will bring growers together, creating opportunities to build mutually beneficial relationships. Future farmers will have access to cultural information to succeed in start-up businesses. Consumers demanding organic produce will have access to locally available, sustainably-sourced produce year round.
Research
Our previous research with synthetic fertilizers has shown differences in crop performance between soilless substrates such as perlite, coir, pine bark, and wood fiber. Therefore, it is imperative that we evaluate interactions between soilless substrate and liquid organic fertilizers before making recommendations to growers.
In the proposed project we will evaluate productivity, physiological and phytochemical changes, and disease suppression when crops are grown under different liquid organic fertilizers and soilless substrates. We hypothesize that Organic fertilizer and soilless substrate interactions are different from synthetic fertilizers.
With on-farm trials, we will assess the transition of the technology based on available growing conditions for farmers. Employing container-based production will address long-standing challenges with soil-based organic production.
The specific objectives of the project are as follows:
- To identify the composition and availability of nutrients in OMRI-approved commercially available liquid organic fertilizers.
- To identify the influence of substrate and organic fertilizer interaction on yield, market quality, plant nutrients, phytochemical properties, and disease suppression.
- To evaluate yield and quality of identified fertilizers and substrates on participating farms with different growing environments.
- To disseminate information to existing and future produce growers interested in organic and sustainable containerized crop production.
The objective 1 has completed , and a graduate student is carrying out research projects related to Objective 2. Objective 3 is based on results of objective 2. Project group have activities in progress with the objective 4.
The project is taking place at the Ohio State University (OSU) Wooster campus greenhouse complex and on farms detailed below.
Phase 1 – Organic fertilizer selection and optimization
Investigators met with small to medium-scale producers collected feedback from Maumee Valley Growers Association. A booth was set up at Mid-Ohio Growers Association and OEFFA (Ohio ecological food and farm association) to get information about growing practices among high tunnel growers. We expect to attend , Great Lakes Fruit, Vegetable & Farm Market Expo, and Mid-Atlantic Fruit and Vegetable Convention collecting input and feedback from our research program. We will conduct listening sessions with growers and surveys to identify organic fertilizers currently in use.
Commercially available OMRI-approved fertilizers were also selected based on macro and micronutrient availability listed on the label. Selected liquid fertilizers were analyzed for tank stability, mixability in water, and delivery with common irrigation systems. Following mixing at the recommended rate, pH, electrical conductivity, and macro- and micro-nutrients (using ion chromatography at the USDA analytical laboratory in Wooster) were measured.
Phase 2- Identification of influence of substrate and organic fertilizer interaction
We conducted the first experiment with cucumber (a fast-growing and short-term crop) in a climate-controlled greenhouse with automated fertigation provided by a drip irrigation system. Throughout the experiment, the average daily temperature, relative humidity, and daily light integral (DLI) were recorded. Our past research indicated that wood fiber-based substrate (Profile Products, Buffalo Grove, IL) was comparable to rockwool in performance and could be used for organic production, and therefore was used as the propagation substrate to generate quality seedlings.
The treatments comprised of selected OMRI-approved organic molasses based fertilizer with identified in phase 1. In the first experiment, five treatments were: molasses-based organic fertilizer, Pre-Empt (PE), at 170 PPM nitrogen with 100 PPM Ca from calcium chloride, 170 PE with 100 PPM Ca from FoxFarm’s Cal-Mag, PE at 120 PPM N with calcium chloride, 120 PE with Cal-Mag, and synthetic fertilizer treatment as control. The conventional control contained recommended water-soluble synthetic fertilizer (Hydro Grow Vine Crop Fertilizer; 97.4 g·L-1; 4.3% N-9.3%P-3.5%K: Crop King Inc. Lodi. OH) and calcium nitrate (74.9 g·L-1; Crop King). Crop canopy management follwed the recommended protocols for highwire crop management. All plants were grown as a single stem throughout the study, by removing axillary shoots were as needed. Vines were trained upwards using polyethylene ropes and vine hooks. Lower leaves were removed as the canopy develops to channel the resources to fruits and new growth. For the harvest, number, fresh weight, and dry weight of fruits were recorded twice a week. Any deficiency and toxicity symptoms were documented weekly. Plant tissue macro- and micro-nutrients (at Ohio State University’s Service, Testing, and Research/STAR laboratory), Brix sugar content, and was measured. Leachate was evaluated weekly for volume, pH and EC changes during production. Leachate nutrient composition will be assessed at representative growth stages to determine nutrient availability in the root zone. The total nitrogen (TN) content of leachate was determined using the total organic carbon analyzer (TOCLCSN, Shimadzu, Kyoto, Japan) and the nutrient compositions of leachate aliquots was determined with an ion-chromatography system (IC 600; Thermo Fisher Scientific, Waltham, MA, USA). Results are as detailed below.
As third stage, we will evaluate the influence of organic liquid fertilizers, soilless substrates and their interaction on yield, market quality, root health, plant nutrients, and phytochemical properties of tomatoes and cucumbers. Experiments will be conducted to assess the impacts of soilless substrates and organic fertilizers on Pythium root rot in cucumbers and Fusarium wilt in tomatoes in inoculated trials. A comparison between synthetic and the selected organic fertilizer/s in containerized production will be made to evaluate yield and quality differences between organic and conventional produce and potential impact on farm income. Economic analysis will be done based on inputs used and market price for conventional and organic produce. Root severity for Pythium root rot and disease progress for Fusarium wilt will be assessed in experiments to determine impacts on diseases. Water and nutrient use efficiency will be compared between treatments.
Phase 3 - On farm trails with selected substrate and organic fertilizer combination
We have identified the following growers for conducting on-farm trials that will employ a range of production systems and growing environments, John Hartmann - (All Season Fresh) and Devon Shaw - (Soul Patch) will represent greenhouse production. Bill Rudy (Evans Family Ranch) and one farmer in Morrow County (identified by Carrie Jagger, OSU Extension) will represent high tunnel growers. The seeds, soilless substrates and fertilizers selected from phase 2 will be provided to the growers. The crop management time will be compensated. Project team will share responsibilities to provide training for the farmers at various stages of production. Post-doctoral researcher and technician will travel to farm sites once every two weeks to evaluate the plants and for sampling fruits. Yield and quality will be assessed to identify ways to further improve production protocols depending on farm resources. When possible, new substrate and organic fertilizers utilized by participating growers will be compared to their conventional system to offer case studies and anecdotes of success for future outreach activities. Growers will provide feedback on their perceptions and acceptability of the soilless substrates and organic fertilizers. Experiments in phase 2 will also contain a conventional control comprised of rockwool (Grodan Inc., Ontario, Canada), as propagation media and perlite (Horticulture Grade Coarse, PVP Industries Inc., Orwell, OH; Perlite) as production media.
Phase 4 – Dissemination of information
The graduate student has presented findings of fertilizer evaluations and preliminary cucumber trail at the OSU symposia in 2025. She will do another presentation at American Society of Horticultural Science 2025.
In the future we will disseminate information to current and future producers using OSU extension and outreach platforms, CSU extension and outreach platforms, articles, blog posts, and meetings with growers in the North Central region. Mid-Ohio Growers meeting. Great Lakes Fruit, Vegetable & Farm Market Expo, Maumee Valley Growers Association, Ohio Ecological Food and Farm Association conference (OEFFA), Ohio Black Farming Conference, Mid-Atlantic Fruit and Vegetable Convention are some of the meetings that we have recognized.
Dr. Samarakoon coordinates an Associate of Applied Science (AAS) degree in greenhouse and nursery management at Agricultural Technical Institute (OSU-ATI)., which includes around 25 students with career choices in primarily in protected agriculture. To train these future farmers, a section on organic vegetable production in containers will be incorporated to the course HORTTEC 2560T greenhouse vegetable production. In addition, hands-on growing section will be added to their practicum experiences.
A workshop will be organized to include introductory information on containerized vegetable production (substrate selection, propagation methods, irrigation, cultivation methods), and the findings from the proposed project. The participants will learn about new soilless substrates and organic fertilizer sources and any special handling needs. The workshop will be hands-on allowing participants to engage through steps in containerized organic production at OSU greenhouses. The workshop attendees will include extension agents from OSU (coordinated by Dr. Matt Kleinhenz) and Central State University (coordinated by Dr. Cindy Folck). County extension agents will then disseminate information to historically underserved farmers interested in containerized vegetable production or organic producers. With collaborations from CSU, we will videotape information and a jointly branded digital workshop training will be posted on OSU and CSU websites.
Following avenues are identified for publications; trade journal articles in widely read industry trade publications, such as GrowerTalks, Produce Grower, Midwest Growers, and Urban Ag News. As detailed in introduction, the research related to containerized organic vegetable production is limited. Therefore, we will publish in American Society of Horticulture Science Journals: HortScience and HortTechnology. We will do oral and poster presentations in American Society of Horticulture Science annual conference and International Symposium on organic crop production in controlled environments.
Project Plan
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Project phases and activities |
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Phase 1 – Fertilizer selection and optimization |
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Surveys at Grower meetings |
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Analysis of nutrients |
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Developing mixing protocols |
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Optimizing methods for tank stability and delivery |
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Phase 2 - Identification of influence of substrate and organic fertilizer interaction |
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Experiment with cucumber |
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Experiment with tomato |
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Disease severity assessment |
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Phase 3 - On farm trails with selected substrate and organic fertilizer combination |
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Greenhouse grower on-farm trails |
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High tunnel growers on-farm trails |
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Phase 4 – Dissemination of information |
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Grower Conferences |
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Workshop - Wooster campus |
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AAS degree curriculum revision |
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Blog posts and digital video |
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Peer-reviewed and trade journal publications |
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During phase 1, we evaluated the macro- and micronutrients against a standard nutrient composition for synthetic fertilizers available for cucumber and tomato. This helped identify possible missing nutrients and insufficient or toxic quantities of nutrients and other elements. Based on that information, we selected single fertilizers or a combination of fertilizers that provided sufficient nutrients to the vegetative and reproductive phases of cucumber and tomato production. The fertilizers were also evaluated for potential depositions in the stock tank, stability of nutrient supply with time after mixing, and formation of biofilms. We identified issues with delivering liquid organic fertilizers using drip fertigation systems in protected culture and methods to rectify any potential issues.
During the phase 2 experiment, there was no significant difference between the organic treatments however leaf tissue analyses revealed manganese and boron levels increased above the sufficiency range in the 170 PE treatments. Meanwhile, nitrogen and potassium dropped below the required range in all organic treatments. A second experiment is on the way with supplemental sources of nitrogen and increased potassium with the goal of supplying sufficient levels of all nutrients.
Future research will apply these findings to with tomato (a relatively slow-growing and long-term crop). In addition to above parameters, total soluble solids (TSS), titratable acidity, firmness, and skin color will be measured in fruits two times during the production cycle.
Project Activities
Educational & Outreach Activities
Participation Summary:
Investigators met with small to medium-scale producers collected feedback from Maumee Valley Growers Association. A booth was set up at Mid-Ohio Growers Association and OEFFA (Ohio ecological food and farm association) to get information about growing practices among high tunnel growers.
Two growers reach out to the Project director with questions regarding organic production issues in a high tunnel and greenhouse.
Graduate student working on the project presented a poster in OSU plant science symposium and graduate research colloquia
An online survey has prepared to release among growers to identify there current usage of soilless substrates and fertilizers as well as production issues.