Compost Exhaust to Provide Nutrients for Plants in Biofilter and Heat for Greenhouse

Progress report for ONE22-427

Project Type: Partnership
Funds awarded in 2022: $29,999.00
Projected End Date: 07/31/2024
Grant Recipient: AdkAction Compost for Good
Region: Northeast
State: New York
Project Leader:
Jennifer Perry
AdkAction Compost for Good
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Project Information

Project Objectives:

This project seeks to:

  1. Monitor and capture heat from the exhaust of active reverse aerated compost piles.
  2. Demonstrate that this heat will make it more affordable and sustainable to operate a greenhouse in a cold climate. 
  3. Capture carbon dioxide, ammonia, methane and nitrous oxide in a biofilter instead of allowing them to escape into the atmosphere.
  4. Record and analyze nutrient data to minimize formation and leakage of CH4 and N2O into the environment.
  5. Understand and document the effects of exhaust nutrients on worms and plants.
  6. Experiment with different biofilter mediums, plants and lighting arrangements to determine best practice for producing profitable and nutritious crops.

We seek to demonstrate that composting and greenhouse production can be mutually beneficial endeavors, diverting food waste from landfills, increasing nutrient input to farms, decreasing heating costs, and increasing production which will increase profitability and quality of life for farmers.  This scalable and replicable project will make entry more affordable for farmers with financial constraints, enabling opportunity for marginalized populations.  The facility is scaled small enough, and designed to capture the gases and therefore odors, so it can easily be located within close proximity to waste generators.



Season extension with high tunnels has been encouraged in our area due to the short growing season, but the operation of greenhouses throughout the winter is cost prohibitive due to heat and lighting.  Our community agricultural systems have become fragmented and lost value found in natural cycling of nutrients and diversity.  This is decreasing profitability for the farmer, resources for local communities and integrity in our environment.  Our waste resources are transported to remote landfills while we are experiencing international fertilizer shortages of synthetic fertilizer which is manufactured mostly overseas, using fossil fuels.  Synthetic fertilizer is only a short-term solution as it is not retained well by the soil, and at risk of run off and environmental contamination.  In the greenhouse industry propane is used to create carbon-dioxide in the greenhouse to increase yield.

New York State is currently beginning mandates for larger Food Waste generators to divert their waste from landfills to composting facilities within a 25-mile radius.  Many areas in New York currently do not have a facility at all, allowing Food Waste Generators to receive an exemption and continue to land-fill their food waste.  Farmers can diversify by composting at a scale that provides for their needs and gives them a product to sell.  Farmers often have land and equipment that is needed in the composting process. In the North Country, during the winter, even the best constructed compost recipes have a very difficult time with uniform heating.  Windrow composting does create a quality product, but with more land footprint, fossil fuel use for equipment handling, possible runoff issues and during the turning process carbon dioxide, methane and nitrous oxide are released into the atmosphere.  These toxic runoffs and “greenhouse” gasses have value to the farmer.

Most farmers have experienced a bind-up of nitrogen due to excess tree debris or corn sileage in manure spread on fields.  This nitrogen is not lost, but the crops in that area will be stunted for the season, as the carbon holds the nitrogen tightly and it takes at least a season, often two or three before the carbon is breaking down and ready to release the nitrogen. 

Livestock Farmers have also experienced strong ammonia off-gas from piled manure with insufficient carbon, and vegetable farmers have certainly over fertilized before, where you may have lush foliage, but no fruit on your plants. Nitrogen can be very volatile and have serious effects on your farm, but also in our environment. 

Ammonia will damage plant leaf tissue in concentrations as low as 10 ppm and must be scrubbed from the exhaust stream before it enters the greenhouse atmosphere. A number of experimental composting greenhouses have suffered chemical bums of leaves by NH3 that was released directly into the greenhouse atmosphere without being filtered.

The NH3 is transformed to ammonium (NH4+) when it comes in contact with the water vapor in the exhaust stream or condenses in the pipe or soil of the growing bed/filter. Some NH4+ is absorbed by plant root hairs but most of it is mineralized to nitrite (N02-) and then to nitrate (N03-) by bacteria present in the biofilter. The biofilter has a high carbon content, which provides a food source for certain nitrifying bacteria. The warm temperatures and oxygen-rich environment of the biofilter also assist in rapid nitrification ofNH3 to plant-usable N03-

Increasing fertility is easier than decreasing it.  Strategies used by farmers to decrease nitrogen include planting hungry crops and introducing carbon, often as old feed, such as sileage, hay. sawdust or other tree debris.  We have experienced these problems first hand.


Farmers historically lack the support from people with technical knowledge, labor resources and funds for testing, tracking, recordkeeping, and dissemination of info for use by other farms.  This grant will enable that collaboration.

We are working with several variables, that if we manage them correctly, we should be able to find the correct balance to harness all the inputs for the best financial and environmental benefit.  These variables include:

  1. Compost recipes and external temperature control will affect gaseous content in the harnessed condensate.
  2. The amount of aeration will affect how quickly and at what temperature the composting process happens, affecting the microbes, types and amounts of gas formed.
  3. The design of condensate movement from the pile to the biofilter will affect the amount of vapor and nutrients that reach the biofilter.
  4. The composition of the biofilter will affect how well it holds the nutrients and how quickly it becomes saturated.
  5. The variety of plants will affect what nutrients are removed and how quickly, and are an integral part of the biofilter itself.
  6. Sufficient lighting will affect the ability of the plants to uptake the nutrients and turn them into profit for the farmer.

Composters who process manures and highly nitrogenous feedstocks will benefit from the deployment of effective N capture systems.  NH4 is commonly the greatest form of N losses from almost all aerobic manure management systems.  Deployment of composting practices that conserve the N value via NH4 volatilization and mitigate GHG releases of CH4 and N2O achieve significant environmental and agronomic goals.

Working in a low income, limited food access area, we are going to demonstrate how pairing a properly constructed and managed composting facility with greenhouse production will not only reduce the costs, but provide increased yield, and additional income stream.  This will improve the profitability and sustainability of local farms while conserving soil and protecting water quality.  It should also lead to enhancement of employment in farm communities and improvement of quality of life for farmers, their employees and the community.


Click linked name(s) to expand/collapse or show everyone's info
  • Bruce Fulford - Technical Advisor
  • Jason McCune-Sanders - Technical Advisor
  • Cherie Whitten - Producer


Materials and methods:

Farm partner, Cherie Whitten, seeks to record and analyze data to minimize formation and leakage of CH4 and N2O into the environment and to understand how to manage exhaust through a biofilter to positively affect nutrient availability and temperature for the worms and plants.  

The biofilter consists of a 30" deep bed of material layered in the bottom of the greenhouse which includes the root zone and the plants growing therein.  The bottom layer of wood chips creates an aeration plenum, so the nutrients in the compost exhaust move evenly into the upper layers.  

We endeavor to match the compost aeration and resulting moisture, gaseous N and CO2 to the needs of plants and worms, and to maintain a healthy enclosed workspace.  Excessive accumulation of nutrients in growing matrices would be detrimental to crop health and yield, and the air quality within the greenhouse must be safe for occupants. 

High-yield greenhouse crops will be selected in our trial to optimize removal of nutrients from the biofilter.  A combination of supplemental lighting will be provided to ensure vigorous crop production and efficient nutrient uptake throughout the winter.

These trials will be conducted in plots of varying biofilter media. This media will include zeolite, aragonite, biochar, clay, rock phosphate, bone char and sawdust.  We endeavor to find the most advantageous mix of media and understand how to adjust it as needed.

Representative sampling and analyses of feedstocks will establish baseline nutrient mass balances to be composted. Aeration regimes and temperature data will be tracked in the composting batches. A control and monitoring package to measure temperature, air flow rate and oxygen content of the compost exhaust will be assembled by Agrilab Technologies, programmed, and tested for this project.  Exhaust gases, biofiltration growing media, plants, and population and nutrient accumulation of Eiseniia foetida will be sampled and analyzed to determine the efficacy and key performance factors within the integrated biofiltration system.

Nitrogen dynamics are highly variable in active compost, soils, exhaust ductwork, and biofiltration media.  As feedstock N decomposes, NH4 and N2O will be generated in varying concentrations based on feedstock composition and compost management. The air handling system, heat exchanger, and condensate removal ductwork will remove some of the NH4 and entrain it as NH3. When ammonia in the exhaust touches the soil, it converts to ammonium, a form of nitrate that bonds to the soil so plants can use it. When too much ammonia enters the soil, or the biofilter becomes saturated, ammonia odors can enter the greenhouse, which can become toxic for the plants. Therefore this approach to biofiltration in greenhouses needs to be done carefully.  The biofilter will capture most or all of the remaining NH4, and mineralize it into plant available N.  The high carbon content of the biofilter soil should buffer the heavy loading rates of NH3 by providing colloidal surface area and increasing the cation exchange capacity.  The worms will digest carbonaceous material and the other amendments and nutrients incorporated into the biofilter.  In this way, some of the N will be converted into worm biomass within the biofilter.  

Nitrification and denitrification processes within the biofilter media will be tracked via representative sampling and analyses in the varying treatments.  Greenhouse atmosphere will be monitored for CO2, temperature and N2O to optimize plant growth and control ventilation to ensure workplace health and safety.  Due to the worms sensitivity to high levels of nutrient build up sampling the movement and health of the worms will help us determine media saturation as well.

Bruce Fulford will review data regularly and will be contacted when there are outliers.  Biofilter media manipulation will produce the mineralization of plant available N.

We will record the following data:

  1. Compost quantity and recipe
  2. Heat provided by the compost
  3. Ammonia in the compost exhaust  
  4. Soil nitrogen at various points in the biofilter
  5. Moisture at various points in the biofilter
  6. Carbon dioxide at various points above the biofilter
  7. Location and condition of the worms
  8. Health of the plants
  9. Yield of vegetables from various plots
  10. BRIX levels of vegetables and plants

With this information we will:

  • Analyze increases or decreases in production quantity and quality in correlation to nutrient and temperature factors.
  • Analyze the cost savings in heating a greenhouse, as well as the reduction in carbon footprint.
  • Estimate the amount of greenhouse gases that were sequestered during this project.
  • Demonstrate improved productivity and reduction of costs.
  • Produce reports that will enable other farmers to duplicate this process, or scale it up.


Progress to date:

Since launching the project in August, 2022, ANCA purchased a biogas monitoring system from Agriblab in Vermont on behalf of partner farmer Cherie Whitten from Whitten Family Farm for $5,000. Cherie has just completed construction of the building that will be housing the composting process – a 30x40 timber frame structure (covered by a different grant). The structure is immediately adjacent to a greenhouse that will be the location of this experiment. Cherie has been collecting food waste from regional entities for three months and will be composting these materials with wood chip mix in early February. Gases from the aerated static pile (ASP) system will be bio filtered and funneled into the adjacent greenhouse this spring and summer. She will be starting plants in the greenhouse in February.  It will be these plants that will be monitored to determine the quality of the exhaust gas entering the greenhouse. Cherie’s next purchase will be for a lighting system to go in the greenhouse.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

CfG consultants/staff will leverage our vast partner network including over 200 stakeholders, Cornell Cooperative Extensions, the ANCA local food program, Adirondack Harvest, the ten local universities (including a strong relationship with Clarkson University), BOCES, and Hub on the Hill to share the results directly, while asking partners to share results with their respective stakeholder groups. 

We are working in partnership with the NYS Department of Environmental Conservation (DEC) to focus and increase farmer engagement through workshops, case studies, eblasts, toolkit development and 1:1 assistance and will incorporate information learned from this project into those efforts. 

To achieve our outreach goals, we will:

  • Disseminate the results to the above groups with a focus on replicability and feasibility through the same processes that we have used to share results from other projects: a graphically designed case study overviewing the project, challenges, results and resources. 
  • Engage others early on so they can follow the project as it progresses, post progress and results on our facebook page and website, send targeted eblasts through the above list and announce completion through a press release.
  • Share the results with the dozens of members of the NYS Organics Council - of whom we are a member - through Biocycle Magazine, and through the Composting Operators course offered by James McSweeney and attended by our staff.
  • Contextualize the results into a bigger picture which would highlight the importance and relevance of the work in light of a current fertilizer crisis, global climate change, soil depletion, and adverse impacts of storm water runoff.
  • Support others who seek to apply the technology or expand upon it through direct support and identification of implementation funding.

In light of COVID and a new return to in person events, it is difficult to identify specific events that will be targeted, however we are planning a farmer workshop this May and plan to host several others throughout the year - again in coordination with the NYS DEC. We have applied for a grant that would target farmers as recipients of our aforementioned support, and would incorporate practices as informed by this project in our toolkit and decision tree.

Interest in this project is already growing as the number of composting entities in the area expands rapidly, each interested in maximizing the beneficial impacts of the composting process. Composters who process nitrogenous feedstocks will benefit from the deployment of effective N capture systems. We have included only a portion of the hours that we will actually spend on outreach on this project.  Much of this will become synergistic with the many programs and funding opportunities which are already the focus of our work.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.