UNH organic dairy farm agroecosystem study, phase III: A closed system, energy independent organic dairy farm for the Northeastern U.S.

Final report for LNE15-344R

LNE15-344R (project overview)
Project Type: Research Only
Funds awarded in 2015: $389,118.00
Projected End Date: 01/31/2019
Grant Recipient: University of New Hampshire
Region: Northeast
State: New Hampshire
Project Leader:
Dr. John Aber
Email
University of New Hampshire
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Project Information

Summary:

From the beginning, this 10-year project has addressed efforts to increase the sustainability of organic dairy farms in northern New England by increasing efficiencies, reducing costs, and also reducing pollution loading to the environment, using the unique opportunity presented by the Organic Dairy Research Farm (ODRF) at the University of New Hampshire (UNH).  The establishment of the ODRF in 2004 attracted significant interest, and support, from the four largest processors of organic milk, and allowed our team access to their technical and financial personnel.  Because of this, we were able to ask the question: “What are the biggest threats to your supply and to your producers?”  The response was the uncontrollable costs of imports to the farm including energy, bedding and grain, as well as the need for a diversified or secondary income stream.  Among the four, there was also variable interest in reducing the environmental footprint of milk production, especially in terms of water quality and greenhouse gas production.

Based on this input, our initial proposal included an integrated process for reducing imported bedding expenses, producing usable heat energy and helping to close the carbon and nitrogen cycles at the ODRF (Figure 1).  The final step in this process, using generated heat to run a greenhouse, was not included as a deliverable for this project, but was considered one possible use, among others, for the very large amounts of heat that we hypothesized would be generated. 

To test the relevance of whatever results we would produce, we used support from the first round of funding for this project, along with NHAES funding, to conduct a survey of dairy farms across New England.  The results established that the ODRF, at ~300 acres, including 100+ of managed woodlands and 100+ of certified organic pasture, was very near the median for dairy farms in the region.

Using Figure 1 as an overall guide, our research has focused on:

1) The conversion of softwood logs to bedding, including economic analyses of this operation.

2) The design, modification, optimization and operation of an aerated static pile composting system with heat capture, fully instrumented to monitor efficiency and performance, and capable of processing all captured organic wastes on the farm.

3) Measurement of trace gas emissions from the composting facility which, along with more standard measures of farm nitrogen inputs and outputs, yields complete nitrogen and partial carbon budgets for the farm that can be compared with similar operations.  Combined with #2, these data are used to calculate the impact of off-farm compost sales on the nitrogen budget.

4) Combining a simple, empirical model of performance by the composting facility with an equally empirical model of energy balance of a greenhouse in order to assess the feasibility of the greenhouse application depicted in the figure.  This effort is on-going.

All of these research initiatives are part of the overall effort to reduce wastes, decrease energy and bedding costs, and increase revenues

All four of these areas have been addressed successfully, with communication of results occurring through workshops, field days and farm visits, video media, a website, Cooperative Extension reports, trade journal magazines, and peer-reviewed publications.  Publication will continue beyond the funding cycle of this grant as recent results make their way through this sometimes frustrating and time-consuming process.

Significant results include:

1) Most dairy farms in New England have significant acreage in second-and-third-growth woodlots.  There is both a local opportunity to reduce bedding expenses by shaving softwoods from these woodlots for bedding materials, and a more general business opportunity for a bedding producer to provide this commodity for dairies within a region.  The current high cost of bedding and the farmer preference for wood-based materials, as derived from survey results, drive this opportunity.

2) The aerated static pile composting process provides several opportunities to reduce pollution loading while also generating both heat energy and a salable product.  The existing system at the ODRF, using manure/bedding materials generated on the farm, can produce 500,000 BTUs of heat energy per day.  The facility also shields the material from precipitation to reduce runoff of organics and nitrogen, speeds the composting process, and produces a final material that has commercial and agronomic value.

3) The nitrogen use-efficiency of farm production at the ODRF is slightly lower than the average for all dairies, but can be increased through the sale of compost.  A strong excess in nitrogen input to the farm through grain imports generates a large nitrogen surplus which allows sale of compost while continuing to build the nitrogen capital of the pastures.

4) Initial results suggest that the heat, nitrogen, and CO2 produced, captured and emitted by the composting facility could be of significant value in extending the growing season and fertilizing crops in moderately-sized greenhouses.  This work is continuing.

Results of this research have been communicated in a number of ways. 

 An excellent video on the aerated static pile composting process was produced by the UNH communications office:    

https://www.youtube.com/watch?v=YNTX5vqN2Fs&feature=youtu.be

This video has been viewed more than 3700 times.

A 2016 review paper on heat-recovery composting published in the peer-reviewed journal Compost Science and Utilization quickly became the most read article in the 25-year history of the journal.

Public presentations have been made to stakeholder groups including a field trip for attendees of the annual BioCycle conference in Boston, a keynote address at the annual meeting of the Maine Organic Farmers and Gardeners Association, a presentation at a US Composting Council Conference & Trade Show, and talks at Rutgers University, the Harvard Forest, and other academic institutions. 

A number of other high-level presentations and field days have been conducted, including a tour for about 40 USDA International Attaches and staff in 2009, a later presentation to Kathleen Merrigan as part of a general report on Sustainable Agriculture at UNH, two presentations to U.S. Senator Jeanne Shaheen and her staff on site at the farm, semi-annual field days for new employees of Stonyfield Yogurt, which are continuing, a group from Zimbabwe representing interests in pasture-based systems and a presentation to the CEO and staff of Aurora Dairies.

Several extension and peer-reviewed publications have also been produced, as well as two Ph.D. theses.  Additional publications in peer-reviewed outlets are anticipated beyond the termination of this project as thesis chapters, and one undergraduate-led project, are submitted into this incredibly slow process.  Publications are listed in the Results section following the text on each of the four initiatives.

Finally, expertise on the project has been sought by a number of private-sector practitioners.  More than 20 examples of these interactions, both domestic and foreign, are listed on the website found below.  We have also accessed the expertise of, and worked closely with, Brian Jerose and colleagues at AgriLab Technologies in Enosburg Falls, VT   http://agrilabtech.com/ throughout this project.

All of these and other outcomes are summarized in a UNH-based webpage for the project at:

https://mypages.unh.edu/agroecosystem/home

 

Project Objective:

Overall objectives: This is the third phase of a ten year project. The initial overall objective of the project was stated in the title of our first proposal: “A Closed-System, Energy Independent Organic Dairy Farm for the Northeastern U.S.”

Based on the input from major dairy milk processors described above, and initial data from the Organic Dairy Research Farm (ODRF) at UNH, this general goal became focused on 4 primary, integrated objectives:

1) Production of bedding from the low-quality forest resource on the farm

2) Processing of manure/bedding materials from the barns in a new, innovative, fully instrumented and largely privately-financed aerated static pile composting system with heat capture technology, allowing detailed measurement of energy, carbon and nitrogen balances over this facility 

3) Measurement of nitrogen and partial carbon balances over the composting facility as well as the whole farm system to provide context for the first two, as well as comparisons with data available from others and to assess the potential to increase efficiency and revenue generation through sale of compost 

4) Assessment of the feasibility of driving extended-season operation of a greenhouse using heat, CO2 and ammonia generated by the composting process

Objectives 1 and 2 were the focus of the first two awards from USDA-SARE, and was concluded under the third.  Work on objectives 3 and 4 were supported by the third award.  Objective 3 has been completed, while work on number 4 is continuing with other support and will be presented this spring.

 

Specific objectives for this third round of funding include:

  1. Further Testing of the Process for Converting Low-Quality Wood to Shavings for Bedding
    Complete analysis of data on production rates, costs, and value of product.  Complete existing Excel-based cost/decision tool for use by farmers and woodlot owners.
  2. Continue Composting Process and Experiments
    As part of workflow on the farm, optimize management of composting facility including timing of initiation, material mixtures, air flow, irrigation, fertilization and other parameters.
  3. Assess the feasibility of Linking the Compost Facility to High Tunnel Production
    Characterize exhaust air from the composting facility as a source for high tunnel production in terms of energy, moisture, CO2, CH4, O2, NH3, and total N. Test biofilters and other processes that can connect exhaust stream to a high tunnel system.
  4. Develop Concepts for Other Uses of Energy Produced Through Composting
    These can include drying shavings, heating adjacent building, and others.
  5. Detailed Carbon, Nitrogen and Greenhouse Gas Budgets
    Develop detailed carbon, nitrogen and greenhouse gas budgets for the farm.  These budgets will include new information on bedding production and composting which will be added to previously available data from farm records and groundwater sampling.  Remeasure pasture productivity, including species composition (e.g. legumes for nitrogen fixation).
  6. Develop Decision Tools for Dairy Farmers, Woodlot Owners and Compost Operators
    These tools will be built using data on costs, sales, yields, efficiencies and productivities developed during this study.  They will be designed to help practitioners optimize management decisions in terms of financial return as well as environmental footprints for nitrogen, carbon and greenhouse gases.  These tools will be relevant to dairy farmers, woodlot owners and compost operators, and will be the first to combine environmental and financial impacts for the alternative processes we have examined (e.g. heat recovery composting, bedding production).
Introduction:

The establishment and unique status of the Organic Dairy Research Farm (ODRF) at the University of New Hampshire (UNH) generated considerable interest among 4 of the major organic milk producers in the U.S.: Stonyfield, Organic Valley, Horizon and Aurora.  At the outset of this project, we had the opportunity to discuss with scientists and managers from these 4 firms their views on the major threats and challenges to the sustainability of the organic dairy system, especially in New England.  Factors seen as major impediments to continued success included cost of imports to the farms, especially of grain, energy and bedding, and the need for secondary or diversified revenue streams.  Also cited was the need, by some producers, to minimize environmental impacts to water quality and to reduce greenhouse gas emissions.  Manure management and composting were cited as possible avenues for progress.  Interestingly, all of these were viewed primarily as means of increasing the sustainability of individual dairy farms, in order to insure consistent supply to processors.

These meetings led directly to the structure and goals of the project reported here.  At the heart of the notion of "A Closed-System, Energy Independent Organic Dairy Farm for the Northeastern U.S." was an integrated system to provide bedding for the barns, heat energy for farm processes, and compost for sale or application to farm fields, with the possible addition of a greenhouse component as well.

This integrated system included four researchable components:

1) Production of bedding from the low-quality forest resource on the farm

2) Processing of manure/bedding materials from the barns in a new, innovative, fully instrumented and largely privately-financed aerated static pile composting system with heat capture technology, allowing detailed measurement of energy, carbon and nitrogen balances over this facility. 

3) Measurement of nitrogen and partial carbon balances over the composting facility as well as the whole farm system to provide context for the first two, as well as comparisons with data available from others and the impact of compost sale as an extra revenue stream. 

4) Assessment of the feasibility of driving extended-season operation of a greenhouse using heat, CO2 and ammonia generated by the composting process.

Cooperators

Click linked name(s) to expand/collapse or show everyone's info
  • Allison Leach (Researcher)
  • Matthew Smith (Researcher)
  • Dr. William McDowell (Researcher)
  • Dr. J, Matthew Davis (Researcher)

Research

Hypothesis:

In the initial proposal, the research effort was expressed in terms of goals rather than hypotheses.  The overall goal was to move the Organic Dairy Research Farm at UNH toward energy independence and nutrient self-sufficiency.  Given the interactions with professionals from the four largest organic milk processors in the country described above, the work was quickly focused on reducing bedding and energy costs, assessing the potential for secondary income streams, and reducing pollution loading, especially for nitrogen.  These goals have been pursued throughout the project.

Hypotheses for this last phase of the project are:

A. Further Testing of the Process for Converting Low-Quality Wood to Shavings for Bedding
   1. Producing high quality bedding material from low quality softwoods will be both technically and economically feasible

B. Continue Composting Process and Experiments
   1. Applications of leachate from composting process will stimulate increases in pile temperature
   2. Pre-heating of winter piles will shorten time required for material to reach optimal temperatures

C. Assess the Feasibility of Linking the Compost Facility to High Tunnel Production
   1. Low-cost biofilters can pre-treat exhaust gases to allow direct venting to greenhouse

D. Develop Concepts for Other Uses of Energy Produced Through Composting
   1. Test value of heated exhaust stream for heating hypothetical, adjacent greenhouse

E. Detailed Nitrogen, Carbon and Greenhouse Gas Budgets
   1. Processing of farm wastes through ASP composting will reduce greenhouse gas emissions
   2. Energy production will allow significant offset of carbon emissions versus fossil fuel use

F. Develop Decision Tools for Dairy Farmers, Woodlot Owners and Compost Operators
   1. A model can be developed that allows optimization of financial and environmental impacts

Materials and methods:

Detailed descriptions of materials and methods used over the course of this study have been published through a number of outlets.  Here we will summarize and outline those methods.  Publications relevant to each study, which include detailed descriptions of methods, are presented in the Results section.

Overview

Our initial proposal included an integrated process for reducing imported bedding expenses, producing usable heat energy and helping to close the carbon and nitrogen cycles at the ODRF.   The four components of the research include:

1) Production of bedding from the low-quality forest resource on the farm

2) Processing of manure/bedding materials from the barns in aerated static pile composting system with heat capture, including detailed measurement of energy, carbon and nitrogen balances. 

3) Measurement of nitrogen and carbon balances over the composting facility and the whole farm system, including gaseous exhausts from the composting process, to determine nitrogen use efficiency of the farm in the context of other reported values, and the potential impact of compost.

4) Assessment of the feasibility of driving extended-season operation of a greenhouse using heat, CO2 and ammonia generated by the composting process

 The final step in the process, using generated heat to actually run a greenhouse, was not included as a deliverable for this project, but was presented as one possible use for the very large amounts of heat to be produced. 

  1. Converting Low-Quality Wood to Shavings for Bedding

Steps in this part of the research included:

1) Initial traditional measurements of the wood resource on the Farm.

2) A survey of dairy farmers across New England to assess bedding needs, materials used, operational issues and costs, as well as basic farm characteristics such as acreage (including woodlands), herd size, etc.  The survey included both conventional and organic farms.

3) Operation of an industrial wood shaving machine to provide data on costs, yields, value of shavings and reliability.  An economic analysis of these data was conducted.

  1. Operation of Aerated Static Pile Composting System with Heat Capture

The Joshua Nelson Energy Recovery Compost Facility was constructed with a generous gift from an anonymous donor, and significant additional support from the NHAES.  Naming of the facility for this pioneer in sustainable energy research was at the behest of both the donor and University.  Joshua Nelson worked closely with Brian Jerose of AgriLab Technologies.

(https://colsa.unh.edu/nhaes/article/unh-names-innovative-composting-facility-after-sustainable-agriculture-pioneer

An informational video about the basic features and operation of the facility has been produced by the UNH Communications Office.

https://www.youtube.com/watch?v=YNTX5vqN2Fs&feature=youtu.be

This video includes scenes of both graduate and undergraduate students at work at the facility.

A very detailed report on the construction and early operation of the facility has been released through NH Cooperative Extension.
2017-Smith-Aber-building-the-facility

As a unique research facility, a high-quality, high-resolution data acquisition system was installed that allowed remote operation of the fan and valve systems, and also supported collection of information on air temperature, vapor pressure, and velocity of air movement at many points in the system (leaving the material, entering the heat exchanger, leaving the heat exchanger, exiting the facility), at one minute intervals.  This high-resolution data set has been used to determine the efficiency of heat production and capture under a wide range of operational conditions, and to model the system.

Material loaded into the composting facility included manure scraped from the farm yard daily, bedded pack material removed from the free-stall barn seasonally, and waste hay or other materials mixed to achieve an optimal carbon to nitrogen ratio.  New batches were loaded as available, depending on farm operations.  Up to 10 150 yd3 batches of material were processed per year, representing essentially all the material generated on the farm.

Given the unique nature of the facility, considerable effort was invested in the first years of this project to redesign and optimize the air handling system, and to install the process control and data acquisition components.  Significant support for this part of the work was provided by NHAES for both materials and the hours required for the installation.  Throughout this process, from initial design to final configuration, we have worked closely with Brian Jerose and colleagues at AgriLab Technologies in Enosburg Falls, VT:  http://agrilabtech.com/

Results from the first few years of experiments at the facility suggested that additional research needed to be conducted on compost irrigation, including the possible fertilization effects of applying leachate from the composting materials, and on increasing the efficiency of winter composting, perhaps by using stored heat energy to pre-heat materials loaded at low temperatures in the winter.  These experiments are on-going with other support. 

  1. Detailed Nitrogen, Carbon and Greenhouse Gas Budgets

To meet the goal of assessing the overall efficiency of nutrient use and some of the environmental impacts on the farm, we have completed a detailed nitrogen budget for the farm, and measured greenhouse gas emissions from the composting facility.

Research completed includes:

1) Collection of detailed data on nitrogen imports, exports and most internal transfers based on data obtained from purchase and sale information for the farm  as well as farm records on feeds and time on pasture.

2) Development and testing of methods for accurate measurement of the efflux of CO2, NH3, methane (CH4) and oxygen (O2) from the composting facility using industry-standard methods for gases at high concentrations.

3) Collection of data on groundwater nutrient concentrations to assess impacts on adjacent waterways

4) Use of these data to develop some standard metrics of farm nitrogen use efficiency and surplus at three levels (whole farm, crop, animal) for comparison with other dairies.

  1. Assess the Feasibility of Linking the Compost Facility to High Tunnel Production

This step in the research is intended as a preliminary examination of the scale of energy and gas production in the composting facility by placing them in the context of their possible value in increasing greenhouse crop production.  Increases could occur through use of produced heat to extend the growing season or reduce heating costs, and/or through fertilization of crop growth with CO2 in the exhaust stream.  If feasible, this step could also provide a final “scrubbing” step that would reduce carbon and nitrogen emissions.  Detailed measurements of ammonia concentration reported below clearly indicate the raw exhaust gas would be toxic to plants unless highly diluted or filtered.  To address this, we have installed two biofilters at the exhaust outlet of the facility and measured the efficiency of ammonia removal by either woodchips alone, or a wood chip/compost mixture.

Activities here include:

1) Construction of two biofilters at the exhaust outlet of the composting facility

2) Measurement of the efficiency of ammonia removal by these two filters under different conditions of ammonia concentration, filter material age, and environmental conditions

3) Building a model of the energy balance of a simple greenhouse system designed to link with the model of the energy dynamics of the composting system

 

Research results and discussion:

Rather than repeating all of the results and discussion in the many publications produced to date, we will in this section provide bullet-point highlights and links to publications where available, or detail plans for publication.  Those areas in which research is on-going are also described.

  1. Converting Low-Quality Wood to Shavings for Bedding

Research on this topic has been concluded, and the results published.  Major findings include:

  • The Organic Diary Research Farm at UNH is near the regional median in terms of acreage, distribution between woodlands and pasture, and herd size.
  • Wood-based products (mainly sawdust) were the most commonly used bedding material in dairy farms across New England
  • Bedding costs had risen 70% between 2003 and 2013
  • Production of low-quality wood on the farm per acre of woodlot is about twice the annual requirement for bedding on the farm, suggesting that sustainable management of the ~100 acre woodlot resource to meet bedding needs is feasible.
  • Operation of a commercial log shaving machine to produce bedding is feasible
  • An economic decision model using data collected during the operation of this machine suggest:

  - The economic breakeven volume for bedding production required a relatively large farm

       size of more than 170 cows

  - The investment payback period for full-time operation was 561 days

  - Full-time operation could produce bedding for 25-30 dairies of average size in New

        England

  • Eastern Hemlock can be shaved into bedding

  - Less absorbent that White Pine

  - Similar characteristics in terms of pathogenic bacteria in bedding samples

  - Lower stumpage value due to Adelgid infestations may increase bedding value

Publications:

 Smith, M.M, J.D. Aber and C.L. Simms. 2017. Animal bedding cost and somatic cell count across New England dairy farms: Relationship with bedding material, housing type, herd size, and management system. The Professional Animal Scientist 33:616-626
2017-Smith-et-al-Bedding-costs-and-cell-count

 Smith, M.M., J.D. Aber and T. Howard.  2017. Economic viability of producing animal bedding from low quality and small diameter trees using a wood shaving machine. The Professional Animal Scientist 33:771-779
2017-Smith-Aber-Howard-Bedding-Economics

 Smith, M.M, C. Andam, C.J. Park and J.D. Aber. 2018 Utilization of low grade wood for use as animal bedding: A case study of eastern hemlock. Journal of Forestry 116:520-528
2018-Smith-et-al-Hemlock-bedding

 Simms, L., M. Smith, J. Alvez, J. Colby, and J. Aber. 2015. Alternatives for rising bedding costs in New England dairies. Dairy Briefs Vol. 62:3-4. University of New Hampshire Cooperative Extension, Durham, NH.
2015-Simms-et-al-Dairy-Brief

 

  1. Operation of Aerated Static Pile Composting System with Heat Capture

This part of the research has also been concluded and results have been published and presented in a number of ways.  Two manuscripts on the detailed modeling of the system await publication.  Important results, based on 4+ years of trials, include:

  • The facility can process all of the farms collected organic wastes
  • Detailed, fine-scale data allow accurate measurement and prediction of the efficiency of energy generation and capture
  • Comparison with published data, mainly from small-scale lab experiments, suggests that lab-based studies seriously over-estimate potential energy yield
  • Under our full-scale, operational conditions, energy recovery of over 30,000 BTU/hour can be achieved with sustainable output of 500,000 BTU/day
  • The primary determinant of energy capture in our system is the differential in temperature between the pile or vapor temperature, and the hot water in the heat sink tank
  • This suggests that efficient use of this energy source requires tight coupling with a useful application of the recovered heat

Publications:

Smith, M. and J. Aber. 2014. Heat recovery from Compost. BioCycle 55:26-28
2014-Smith-and-Aber-Biocycle

Smith, M. M., and Aber, J. D. 2014. Heat recovery from compost: A guide to building an aerated static pile heat recovery composting facility. Durham, NH: University of New Hampshire Cooperative Extension; Research Report. 81 p.

Smith M. M., Aber JD. 2015. Heat extraction & utilization from composting as an alternative to anaerobic digestion for reducing energy costs at dairy farms. UNH Dairy Report 2015: New Hampshire Agricultural Experiment Station and University of New Hampshire Cooperative Extension; 2015 pp. 33-35.

Smith, M., J.D. Aber and R. Rynk. 2015. Heat Recovery from composting – a comprehensive review. Abstract presented at International Composting Conference. Beijing, China. October 2015

Smith, M., J.D. Aber and R. Rynk. 2016. Heat recovery from composting – a comprehensive review of system design, recovery rate and utilization. Compost Science and Utilization 25(S1):11-22
2016-Heat-Recovery-from-Composting-A-Comprehensive-Review-of-System-Design

Smith, M. M. 2016. Creating an economically viable, closed-system, energy-independent dairy farm through the on-farm production of animal bedding and heat capture from an aerated static pile heat recovery composting operation. Ph.D. Dissertation. University of New Hampshire, Durham. 267 p.

Smith, M.M and J.D. Aber. 2017. Energy Recovery from Commercial-Scale Aerated Static Pile Composting as a Novel Waste Management Strategy. Applied Energy 211:194-199
2017-Smith-Aber-Applied-Energy

Smith, M. M., and Aber, J. D. 2017. Heat recovery from composting: A step-by-step guide to building an aerated static pile heat recovery composting facility. Durham, NH: University of New Hampshire Cooperative Extension; Research Report. 64 p.
2017-Smith-Aber-building-the-facility

Smith, M. M., and Aber, J. D. 2017. Recover energy from composting to heat water on farms. Progressive Dairyman 19:61-63 and Progressive Dairyman Canada. 3:63-65.

Smith, M. M. Heat recovery from composting. In Rynk. R. (ed). The on-farm composting handbook. Second Edition. Compost Council’s Research and Education Foundation. Reston, VA. Book chapter submitted, with a publication date of early 2019.

Aber, J.D., M.M. Smith and A.M. Leach. Optimizing Performance of an Aerated Static Pile Composting System for Energy Production and Capture: An Empirical Model. Manuscript completed

Smith, M.M., J.D. Aber and A.M. Leach. Impact of Long-term Composting Cycles and Extended Aeration on Heat Yield from a Multi-bay Aerated Static Pile Composting System with Heat Recovery. Manuscript completed

 

  1. Detailed Nitrogen, Carbon and Greenhouse Gas Budgets

 

This part of the project has been a focus for the last 2 years.  Research or trace gas emissions and nitrogen cycling has been completed and presented in thesis format and is publicly available through the UNH Library.  Manuscripts for peer-reviewed publications are being prepared.  The biofilter part of this work is on-going and will be completed with other support in the spring of 2019.  All of this work will be summarized and presented in terms of farm nutrient use efficiency and potential pathways for reduction of environmental impacts from dairy farms.  Primary results include:

 

  • Carbon emissions from the composting system are almost entirely as CO2 (up to 10% of air by volume) with only trace amounts of methane (usually less than 2ppm).
  • Ammonia concentrations are very high (routinely 1000ppm, occasionally to 4000ppm)
  • Both CO2 and ammonia concentrations increase logarithmically with vapor temperature
  • A large whole-farm nitrogen surplus of over 5000 kg N per year, resulting from imported grains, suggests that the sale of compost as a secondary income stream would not reduce overall pasture productivity
  • The farm as a whole has relatively low inputs and outputs of nitrogen compared with other dairy farm data in the literature, and has a moderate nitrogen use efficiency (nitrogen in milk divided by nitrogen inputs) of about 25%.
  • Whole-farm nitrogen use efficiency could be increased to 31% or 41% by sale and export of 20% or 50% of produced compost, respectively

Publications

 

Leach, AM, J Aber, M Smith. Closing the agricultural loop: Capturing and utilizing compost gas effluent from aerated static pile composting. Poster presentation, International Nitrogen Initiative Conference. Melbourne, AU, December 2016

 

Leach, A.M. 2018. Addressing the nitrogen challenge: Footprint tools and on-farm solutions. Ph.D. Dissertation. University of New Hampshire, 90pp.

 

Leach, A. M., Aber, J. D., Smith, M. M., and Williamson, N. Characterizing compost exhaust gas from aerated static pile heat recovery composting. To be submitted to Biomass and Bioenergy.

 

Leach, A., J.D. Aber, and M. Smith. The effect of exporting compost on an organic diary farm's nitrogen budget.  To be submitted to the Journal of Sustainable Agriculture, or similar.

 

 

  1. Assess the Feasibility of Linking the Compost Facility to High Tunnel Production

This part of the work is now in progress and relates to processing vapor exhausts from the composting facility through a biofilter, and calculating the potential gains in energy savings and carbon fertilization by utilizing the warm, humid, filtered, CO2-enriched air.  The model of energy balance for the composting facility made possible by our detailed, 1-minute-time-scale measurements of heat production, is being paired with a simple model of the heat balance of a high tunnel greenhouse.  This work will continue past the end date of the award using other sources of support and will be ready for presentation in the spring of 2019.  Preliminary results include:

  • A 40’ by 20’ polycarbonate high tunnel greenhouse in Durham, NH during one of the coldest Januarys is history (2014) would have required an average heat input of ~800,000 BTU/day. Full-year demands are being calculated
  • The UNH compost facility can capture ~500,000 BTU/day in the heat sink, with additional heat being available by direct use of the 90F, CO2-enriched exhaust gas
  • The continuous nature of both heat production by the composting facility and heat demand by a greenhouse suggests effective linking of source and sink may be possible
  • Impacts of direct use of exhaust for heat and the potential for CO2 fertilization are also under investigation
  • Simple biofilters constructed using either wood chips alone or woodchips mixed with compost remove 80-90% of ammonia in the exhaust stream at operational concentrations
  • There is a clear need to filter ammonia from the exhaust stream before any direct venting into a greenhouse is considered

 

Publications:

 

Williamson, N.A., J.D. Aber, A. Leach, M. Smith. Ammonia removal with compost-woodchip

biofilters from a commercial scale composting facility. (In preparation)

 

 

 

Research conclusions:

1) Many dairy farms in New England include significant woodland holdings that can support sustainable softwood production and provide feedstock for a wood shaving process that can meet bedding requirements.

 

2) Operation of a commercial-grade wood-shaving machine is marginally non-profitable for individual farms of typical size in New England, but becomes profitable as a commodity producing enterprise or multi-farm cooperative.

 

3) An aerated static pile composting system of the size at the ODRF can produce up to 500,000 BTU/day of usable heat energy and process all of the organic wastes collected in the farm’s barn system.

 

4) Efficient use of the produced heat requires a relatively continuous demand during periods of compost production. 

 

5) The ODRF has an annual nitrogen surplus of ~ 5000 kg per hectare per year and a nitrogen use efficiency (nitrogen in products divided by nitrogen imports in grain and hay) of about 25% - a relatively low number.

 

6) Nitrogen use efficiency can be increased to 31% and 41% through the sale of 20% and 50% of produced compost, respectively, while maintain a net nitrogen gain to the pastures

 

7) A simple biofilter of either wood chips alone, or wood chips with compost, can consistently remove ~80% of ammonia from the exhaust stream of the composting facility.

 

8) Initial calculations and modeling efforts suggest that the heat and CO2 generated by the composting facility would pair well with a moderately-sized greenhouse in terms of extending the growing season or reducing heating costs.

 

Participation Summary

Education & Outreach Activities and Participation Summary

Educational activities:

23 Consultations
10 Journal articles
25 On-farm demonstrations
12 Online trainings
7 Published press articles, newsletters
25 Tours
21 Webinars / talks / presentations
8 Workshop field days

Participation Summary:

110 Farmers participated
300 Number of agricultural educator or service providers reached through education and outreach activities
Outreach description:

In addition to the publications listed above, we have communicated our approach and results through a large number of workshops, field days and farm visits, video media, and a project website.  These include:

 

 An excellent video on the aerated static pile composting process was produced by the UNH communications office:    

https://www.youtube.com/watch?v=YNTX5vqN2Fs&feature=youtu.be

This video has been viewed more than 3700 times.

Public presentations have been made to stakeholder groups including a field trip for attendees of the annual BioCycle conference in Boston, a keynote address at the annual meeting of the Maine Organic Farmers and Gardeners Association, a presentation at a US Composting Council Conference & Trade Show, and talks at Rutgers University, the Harvard Forest, and other academic institutions. We have also presented at the winter conference of the Northeast Organic Farming Association, and the Tin Mountain Conservation Center.

A number of other high-level presentations and field days have been conducted, including a tour for about 40 USDA International Attaches and staff in 2009, a later presentation to Kathleen Merrigan as part of a general report on Sustainable Agriculture at UNH, two presentations to U.S. Senator Jeanne Shaheen and her staff on site at the farm, semi-annual field days for new employees of Stonyfield Yogurt, which are continuing, a group from Zimbabwe representing interests in pasture-based systems and a presentation to the CEO and staff of Aurora Dairies.

Finally, expertise on the project has been sought by a number of private-sector practitioners including:

Domestic

  • Ideal Compost (Commercial Operation)
  • Northeast Resource Recovery Association 
  • Wolfe’s Neck Farm, ME
  • Connecticut Resource Conservation & Development Area, Inc.
  • Strongwater Farm Therapeutic Equestrian Center, MA
  • Lewis Farm, NH
  • Alternative Energy Associates, NJ
  • Neal Sanders, NH (Fiction Novelist)
  • Brixham Montessori Friends Elementary School, ME
  • Razzano Farm, New Jersey
  • Ideal Compost, Peterborough, NH
  • Moor Farm/Stewardship & Sustainability, Durham, NH
  • Seacoast Energy Alternatives, Dover, NH
  • Hall and Moskow Real Estate, Newburyport, MA
  • The Peters Company, Lee, NH
  • Aquaponics & Compost Heat Recovery Venture, Manchester, NH
  • Payeur Farm Composting, Parsonsfield, ME
  • Fox Composting, Dover, NH

International

  • Brno University of Technology, Czech Republic
  • Fusion Expert Consulting, Inc, Canada
  • LM Tree Solutions, United Kingdom
  • National Agriculture and Food Research Organization (NARO), Japan
  • Superior Technical School of Architecture (ETSAM), Madrid, Spain
  • Earthbank Resource Systems Ltd., British Columbia, Canada  

We have also accessed the expertise of, and worked closely with, Brian Jerose and colleagues at AgriLab Technologies in Enosburg Falls, VT   http://agrilabtech.com/ throughout this project.

 

 

Learning Outcomes

Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

We have not conducted surveys of our visitors.  Tours are always well-received.  The number of Aerated Static Pile composting sites in increasing, and those facilities recently built have used our publications and site tours as input to their own processes.

Most visitors to our research site had not previously been exposed to the concept of Aerated Static Pile composting with heat recovery. Anecdotally, most come away very impressed with the possibilities. We always present the entire cycle, from woodlot, to shaving machine, to bedding in the barn, to energy-yielding composting, to distribution to enrich farm soils. The long list of research consultations, and the fact that our paper in Compost Science and Utilization quickly became the most frequently read, indicates a high level of interest in this integrated system.

As the only Organic Dairy Research Farm in the northeast, visitors are also intrigued by aspects of pasture management, environmental impacts (such as reduced nitrogen and greenhouse gas loss), milk yield, etc.

 

Project Outcomes

6 Grants applied for that built upon this project
6 Grants received that built upon this project
$105,000.00 Dollar amount of grants received that built upon this project
1 New working collaboration
Success stories:

Two Ph.D. students have completed there thesis work and are gainfully employed in related fields.

Assessment of Project Approach and Areas of Further Study:

We feel that the project has been extremely successful.  Being able to design, build and operate the only commercial-scale ASP composting system at a research university has allowed us to test a number of alternative management strategies for this technology and provide realistic estimates of its potential for farm, municipal and commercial applications.  Having this facility embedded in the only Organic Dairy Research Farm at a land-grant University has allowed placing the composting process in a full-farm operation, with links to forest management, bedding production and the impact of these on all-farm carbon and nitrogen cycling.

One part of the project that remains incomplete is the overall farm model proposed for the final year of the project.  We have completed important parts of this model, including an economic analysis of the wood shaving process, and a detailed modeling of the energy, carbon and nitrogen balance of the composting system.  We will shortly complete a feasibility study on linking the composting facility to a greenhouse.  What remains is to integrate these pieces and add additional financial components as possible.  This work will continue through efforts of the PI and student associates through 2019.

 We have also been in communication with the Cooperative Extension office at UNH about the potential for a substantial publication, on the scale of our first detailed report on the construction of our ASP system, that would provide detailed, practitioner-oriented information on the energy management of the bedding-compost-biofilter system.

The logical next step in this research effort would be to physically connect a greenhouse to the ASP system at the ODRF or at another location to test the ability to reduce heating costs and enhance crop production through carbon dioxide fertilization. An extension effort to assist development of a regional cooperative wood shaving enterprise could also help put the results of this study to work.

 

 

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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.