Improving Access to Soil Carbon Proxy Testing: Training Educators to Monitor Soil Health

Progress report for ONE20-378

Project Type: Partnership
Funds awarded in 2020: $29,266.00
Projected End Date: 07/31/2023
Grant Recipient: NOFA/Mass
Region: Northeast
State: Massachusetts
Project Leader:
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Project Information


NOFA/Mass will scale up soil health technical assistance around the region and collect longitudinal data from three farm partners who will use the carbon proxy test results to inform their practices and improve soil health. The NOFA/Mass soil carbon proxy testing program provides on-farm soil health assessment, using a range of soil health indicators as proxies for a relative level of soil carbon sequestration capacity. 

At NOFA/Mass we continue to see a demand for technical assistance that outstrips our ability to meet it. We will scale up by building capacity for testing in neighboring states, New York and Connecticut, and also by offering increased testing within Massachusetts. In each of the three states—NY, CT, and MA—carbon proxy testers will collect longitudinal data by testing the same farm for three years and monitoring changes in soil health. The soil is a formidable carbon sink but will only serve that purpose if—on the individual farm level—farmers all over the world, large and small, understand how their management practices impact the capacity of their soil to build soil carbon over time.  

Our project outreach will include distributing four publications on the topic of carbon soil restoration including our White Paper "Soil Carbon Restoration: Can Biology do the Job?".  We will also leverage our newsletter, podcast, and webinar audience, and our partners at the Massachusetts Healthy Soils Action Plan Advisory Team, OpenTEAM field methods working group, the National Healthy Soils Policy Network, and in the Soil Carbon Coalition to share outcomes. 

Project Objectives:

This project seeks to demonstrate that farmers can better increase soil carbon once they have had their soil tested and can subsequently work with the results to improve management practices. In addition to testing, we will interpret and review results with the farmers who manage each of these three properties as they work to improve soil health.  The three farms participating in the multi-year data collection are diversified vegetable farms and collectively cultivate 329 acres. 

This project also seeks to improve access to soil carbon proxy testing by training three additional testers. Caro Roszell, the NOFA/Mass Soil Carbon Program Coordinator, will train two NOFA-NY staff members and one CT NOFA staff member to be able to conduct soil carbon proxy testing in their states.  

If the project is successful, the three farms that are partners in the study will see the most immediate benefit, but the results will serve as a model that will benefit other farmers around the country. We will disseminate the success of the three partner farms to thousands of people in NOFA/Mass digital media outlets (see below). There is the added benefit of jump starting soil carbon proxy testing programs in CT and NY. 


Current levels of atmospheric carbon are so high that we can not choose between reducing emissions and sequestering carbon. We must do both. And Farmers are significant influencers in climate change; over millennia, generations of farmers have transferred significant amounts of carbon to our atmosphere and oceans. In a paper published in the Proceedings of the National Academy of Sciences, Sandeman et al estimate that “soil carbon debt” to be approximately 133 Pg C (Sanderman, et al).

Yet that debt can be repaid. With attention to how management practices influence soil health, farmers can learn to reverse this trend and become soil carbon accumulators. Indeed, an increase of only 0.4% soil organic carbon across the world’s farmland would effectively offset 20–35% of global anthropogenic greenhouse gas emissions. Farms employing Healthy Soils Practices are seeing soil carbon levels increase from a baseline of 1-2% up to 5-8% over ten or more years, which adds up to 25 to 60 tons of carbon sequestered per acre. 

But soil carbon is highly labile, forming and breaking bonds with other elements constantly, entering the soil and leaving it again through respiration. As a result, soil carbon is difficult to isolate and measure with much accuracy. An alternative approach—the one we use—is to observe the soil as an ecosystem, and directly measure the aspects of soil biology that correlate with and indicate the presence of carbon. Those soil features are “proxies” for carbon. Such tests are inexpensive, immediate, directly observable, and can be done on the farm. With funding from SARE, NOFA/Mass will make this testing program available to more farmers to help them monitor the impact of management practices on their land.

Of course, while climate change mitigation is a great public benefit, many individual farmers are more immediately motivated by soil health impacts on farm viability. Carbon-degraded soils are more vulnerable to storm-related erosion and drought, and can incur costs for farm operations (ie, poor water holding capacity and poor root penetration resulting in increased irrigation needs, reduced nutrient holding capacity leading to higher input costs). In fact, a recent NRCS-funded case study by American Farmland Trust (Quantifying Economic and Environmental Benefits of Soil Health) found an average ROI of 207% on soil health practices for participating farms.

In the nearly 10 years that NOFA/Mass has been educating about soil health and soil carbon, we have seen a dramatic rise in farmer interest in soil health. But the time-intensive nature of farming means it is challenging for farmers to take the time to evaluate their own soils in a detailed manner. Furthermore, blind spots can prevent growers from identifying problems with their soils. According to research published in the American Journal of Alternative Agriculture, length of land tenure correlates with reduced accuracy in soil health assessment by farmers (Liebig, & Doran). Indeed, in our work with farmers, we have found that many experienced farmers are surprised to learn that they have certain soil health obstacles, and subsequently adjust their practices.


Click linked name(s) to expand/collapse or show everyone's info
  • Jeremy Barker Plotkin - Producer
  • Dina Brewster
  • Richard de Graff - Producer
  • Steve Munno - Producer
  • Bethany Wallis


Materials and methods:

Our method for increasing access to testing and training other testers will involve multiple on-site training sessions at Grindstone Farm in Pulaski, NY and Massaro Community Farm in Woodbridge, CT. These are two of our farmer partners for this project. Caro Roszell, the NOFA/Mass Soil Carbon Program Coordinator, will travel to NY to train both of the trainees at Grindstone Farm. The training will take place over three sessions and each training will include one full test collection and analysis. 

In Connecticut, Caro will train a staff member from CT NOFA at Massaro Community Farm. The training will also take place over three sessions and will be a complete test collection and analysis. We will also conduct baseline testing in year 1 at Simple Gifts Farm in Amherst, MA, the third partner farm in this project. The 8 components of our soil carbon proxy testing are: soil surface biology, subsoil observations (soil texture, topsoil depth, root behavior, biopores),  bulk density, water infiltration, slake test, earthworm count, soil hardness, and active carbon. Each test is briefly described below.  

The “Soil Surface Biology” test involves recording  surface observations to track percent of soil covered / bare soil percentage, presence of soil crusting, percent living cover, plant species diversity, and non-plant life forms present. Soil coverage promotes better soil health; percentages of living cover, residue, and mulch can indicate soil management practices . Non-plant life forms like specific kinds of insects, fungi, and animal burrows can also be indicators of soil health. 

The “Digging a Hole” set of tests involves moving one cubic foot of soil to a tub, and then sub-surface observations are recorded: topsoil depth, root depth, root sheathing, root behavior, presence of biopores, soil texture, and size, type and prevalence of aggregates. Stronger aggregation, deeper and more well-branched roots, well-sheathed roots, presence of soil biopores, and deeper topsoil are all indicators of soil health. 

The bulk density test refers to how compressed the soil particles are, and the relative presence of soil pores. We take bulk density samples for 0-4, 4-8, and 8-12 inches. Healthier soils, including those with higher carbon, support more life and tend to have lower density. We compared results against an NRCS table of ideal bulk density levels for different soil types in order to evaluate their bulk density by their soil type. 

The water infiltration test measures the capacity of soil to absorb water and not let it puddle on the surface or run off and erode sloping ground. Better infiltration is correlated with higher levels of soil health, as it indicates more pores and aggregates, which mean greater carbon and soil health.

The slake test compares the growing area to a fencerow or other nearby undisturbed soil area, and records the percentage of the field soil sample and the fencerow sample that remains in the basket after one minute being submerged in water. 

We count the earthworms in a cubic foot of soil (soil that was displaced during the digging a hole protocol) because soils that are higher in soil biological activity and retain moisture better without becoming waterlogged tend to contain more earthworms.

Measuring soil hardness is important because tillage and use of heavy equipment, particularly on wet soils, damages soil pores and lead to runoff, erosion, slow infiltration, and poor water storage. Most crops cannot send roots into soils requiring penetration pressure of 300 pounds/square inch (psi) or more. Similarly, mycorrhizal fungi growth and mobility of other soil organisms is restricted by compacted soil. Identifying and locating such compaction can help growers understand if remedial measures are needed such as mechanical loosening or biodrilling cover crops to break up plow pan and improve soil structure. 

In the active carbon test, soil is mixed with a solution of potassium permanganate, which starts off a deep purple in color. As the permanganate oxidizes the active carbon it loses some of its color and changes toward pink or even clear. The amount of color change can be graded on a color chart.  Active or labile carbon is the portion of soil organic matter which can serve as a ready food source for soil microbes.

In addition to testing the three partner farms each year, Jane Hammer, NOFA/Mass soil technician, will continue to test farms around Massachusetts and work with farmers to understand their results and make improvements. Jane will test seven farms each year, 21 farms throughout the three-year period. Seven Massachusetts vegetable farms for the first year have been identified, vegetable fields will be the focus of the testing. These farms are located in different areas of the state, and range from 5 acres to 90 acres. The farms that will be tested in subsequent years will also be vegetable operations and represent geographic diversity. NOFA/Mass is reaching out to the farmers to request their participation; farmers are identified in many ways including previous participation in NOFA/Mass educational offerings and recommendations from state agencies. NOFA/Mass is confident in our ability to test seven farms each year because of our experience with on-farm testing over the past several years. 

NOFA/Mass will also publish two newsletter articles each year in addition to producing a podcast episode and webinar on the topic of soil carbon restoration. Newsletter articles will be written by the following NOFA/Mass staff members: Christy Bassett (Communications Director), Caro Roszell (Education Director and Soil Carbon Program Coordinator), Jane Hammer (Soil Technician), and Jocelyn Langer (Executive Director). The podcasts will be produced by Jason Valcourt, the NOFA/Mass PR Coordinator and Podcast Producer. Webinars will be created by Anna Gilbert-Muhammad, the NOFA/Mass Webinar Coordinator. We will also revise, print, and distribute our White Paper "Soil Carbon Restoration: Can Biology do the Job?", a 48-page report “The Carbon Sequestering Garden”, and two additional trifold brochures on the topic of soil carbon. These publications will be available at the NOFA/Mass conferences (attracting over 800 people each) and at outreach events where we interact with thousands of people each year. 

Participation Summary
3 Farmers participating in research

Education & Outreach Activities and Participation Summary

2 Published press articles, newsletters
5 Webinars / talks / presentations
2 Workshop field days
2 Other educational activities: Podcasts

Participation Summary:

13 Farmers participated
Education/outreach description:

Over the course of the project, we will disseminate progress reports through our annual newsletter articles, podcast, and webinar. Last year our average number of views per webinar was 215 viewers, there have been over 4,500 downloads of our free podcasts over the past year, and there are over 6,000 subscribers to the NOFA/Mass newsletter. The NOFA/Mass podcasts, webinars, and newsletter articles are evergreen resources and we have observed content engagement increasing overtime. 

At the conclusion of the project, we will compile the longitudinal data from three years of testing on the three different sites into a report that can be presented to other farmers to demonstrate how working with carbon proxy testing can lead to improved soil health. This report will also be made available in the NOFA/Mass newsletter and website, and through our partners in NOFA-NY and CT NOFA. 

NOFA-NY additionally plans to offer annual workshops (exact educational event to be determined) explaining the results of the project for each of the three years. NOFA-NY offers educational programs throughout the year including on-farm field days and a large annual winter conference. In 2018 NOFA-NY had over 1,100 people in attendance at their workshops. We are confident that the results of our work will reach a wide audience between the workshops, newsletter articles, podcast, webinar, and final project report. 

NOFA/Mass will also share project learning with the healthy soils networks that our staff are active in, including the Massachusetts Healthy Soils Action Plan (MA HSAP) Advisory Team. NOFA/Mass's Policy Director, Marty Dagoberto, serves on the MA HSAP Advisory Team, along with the Regenerative Design Group, Linnean Solutions, and Eric Toensmeier, carbon farming expert and researcher for Project Drawdown. This team works closely with a diverse Working Group of 30 researchers, farmers, foresters, conversationists, and soil scientists. NOFA/Mass staff are also active in the OpenTEAM field methods working group, the National Healthy Soils Policy Network, and in the Soil Carbon Coalition. 

However, more significant is that the public dissemination of our work is the multi-directional learning model that we employ at NOFA/Mass. Through our grassroots work with farmers, we are able to help farmers engage with the larger research and policy networks that we participate in. For example, one of our soil health farmer learning groups is contributing data to the OpenTEAM / Real Food Campaign database that correlates crop nutrient density with farm management practices and soil health indicators (specifically, soil organic matter and soil organic carbon at 10 and 20 cm as well as respiration). Through this project, the Massachusetts farmers engaged in data collection also receive special access to national results through regular contact with the researchers leading that national project. 

Our soil health projects, like the one we propose here, enable farmers to participate in larger regional networks that they would otherwise not necessarily have access to, and allow for peer-top-peer, peer-to-network, and network-to-peer farmer learning pathways. 

2020 Outreach activity:
NOFA/Mass wrote one article in this grant period, published in our newsletter. NOFA_Mass, CT NOFA and NOFA-NY to Expand Soil Carbon Proxy Testing with SARE and Farmer Support – NOFA_Mass

2021 Outreach Activities:
In 2021, NOFA/Mass completed two podcasts, one webinar, two NOFA Summer Conference workshops, two on-farm soil health events, and two newsletter articles as a  part of this project, reaching over 3300 individuals. We have also been expanding our Spanish-language event offerings, and offered one workshop in Spanish, which is still available streaming. The following education-related activities were performed in 2021 as a part of this project:


  • Closing Nutrient Cycles with Noah Kellerman (Season 4 Episode 5, August 2021) 370 downloads
  • Compaction Mitigation Strategies with Julie Rawson (Season 4 Episode 8, December 2021) 206 downloads

Webinars: Compaction Mitigation with No-Till Practices – 12/14/21 – Chuck Currie & Maggie Payne. This webinar will be available on YouTube in early 2022.

Workshops: 2021 Summer Conference:

  • Soil Biodiversity and Characteristics of a Healthy Soil – Ruben Parrilla – Monday, August 2, 2021. In respect to productive soils in agriculture, biology is perhaps the most important factor to consider and understand. In this presentation we will briefly cover the different soil trophic levels, their importance, and how to identify some features that are indicative of healthy soils. (presented in Spanish with English translation). 22 participants, 35 streaming views (English translation), 6 streaming views (Spanish translation)
  • NOFA/MA Soil Tech Team – Laura Davis, Anna Gilbert-Muhammad, Ruben Parrilla, and Jane Hammer – Wednesday, August 4, 2021. Over the last 5 years, NOFA/Mass has developed a comprehensive soil technical assistance program to assist growers of all sizes to enhance soil fertility and grow nutritious organic food. The team presented the programs and services that address the physical, biological, and chemical pillars of soil health. 19 participants, 7 streaming views

On-Farm Events:

Newsletter Articles:

In addition to the education and outreach activities undertaken by NOFA/Mass, CT NOFA also developed the following workshops and education events relating to soil health and soil carbon:

  • Best conservation Management Practices in Agriculture – Cynthia Rabinowitz – March 6, 2021
  • Building Soil Carbon for Gardens, Farms, Health, and World – Julie Rawson & Jack Kittredge – March 6, 2021
  • Soil Health Series - Wednesdays April 7, 14, 21
  • Microscopy Lunchtime Series - first Wednesday of the Month - May, June, July, August, and September 2021
  • A Closeup Look at Composting - September 2021. Video link:
  • Compost and Compost Tea for Improved Crop Production - September 2021

Learning Outcomes

10 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas in which farmers reported changes in knowledge, attitude, skills and/or awareness:

For the first quarter of this grant, the goal was primarily to begin training NOFA-NY and CT NOFA staff. We did begin that process and were able to accomplish one in-field training test in each state (ahead of schedule) on behalf of Steve Munno of Massaro Community Farm in Woodbridge CT,  Dick DeGraff of Grindstone Farm in Pulaski, NY, and Gaining Ground Farm in Concord, MA.  Steve, Doug and Dick received information about soil testing through our work on their farms. Jane Hammer, our Soil Technician, completed one test on one farm in the fall but due to an ongoing family health emergency had to postpone the other scheduled tests until the springtime.

Dick DeGraff specifically reported being very surprised at the difference between his soil health indicators on his tilled annual vegetable fields and his 10-year asparagus beds. The infiltration test in particular helped to increase his awareness of soil health indicators, as his tilled, non-cover cropped annual vegetable field took 3 minutes and 24 seconds for 1 inch of water to infiltrate, compared to 27.43 seconds in his asparagus beds in the same field (about 10 yards between testing sites).

Most of the change in knowledge and awareness, however, occurred at the staff level as the technical staff build knowledge of testing protocols and how to interpret results for farmers.

In 2021, Jane Hammer and Soil Tech Coordinator Ruben Parrilla performed carbon proxy tests at 6 Massachusetts farms in addition to Simple Gifts Farm. Jane and Ruben discussed the tests and procedures with the farmers while on-site, and provided them with a report of findings. The test reports provide a detailed assessment of the findings, the importance of each metric, and a brief summary of different management changes farmers can make to improve their soils and carbon sequestration. While we did not receive any direct feedback from the farmers in response to this, we assume that the farmers directly benefited from having Jane and Ruben discuss the tests they were performing and the relationship between each farmer's management practices and soil health.

Project Outcomes

1 New working collaboration
Project outcomes:

At this stage, we have only begun training NOFA staff in the protocols and have completed two initial analysis on two partner farms. However, the partner farms have not yet completely digested the results of those tests or made any changes to practices as a result.

Assessment of Project Approach and Areas of Further Study:

In reviewing our protocols at the time of application, we realized that we had actually updated our protocols since submission. The updates accomplished two things: 1) They brought the NOFA protocols into alignment with NRCS recommended in-field assessment methods and 2) they streamlined and simplified some testing.  Specifically, the tests that were changed were that the aggregate stability protocol was replaced with a simple slake test (comparing field with fencerow) and the soil respiration test was removed. Finally, we added a biopores count and rhizosheathing to the protocols, which are done in the course of the digging a hole protocol and do not involve any equipment or materials cost. 

In addition to these changes to the carbon proxy test protocols, there was interest and excitement on the NOFA soil health staff level to learn how to do basic microscopy, which is a skillset that Monique Bosch of CT NOFA brought to our group. She has been offering soil microscopy trainings to farmers and gardeners, and can train our staff in basic soil biology identification and other soil components (fungi, broad types of bacteria, sand, aggregates, etc).

As a result of these changes, I met with Candice Huber to review a proposed revision to our materials budget to remove some items no longer needed and add 2 microscopes (one for NOFA/Mass and one for NOFA-NY). Using current staff time already in the budget, we will accomplish the carbon proxy testing training as well as training in basic microscopy for our staff. 

Our goal is to explore the possibility of adding a basic fungal to bacterial ratio to the carbon proxy testing protocols, either as a standard or add on service. This is currently an in-demand evaluation that is not widely offered by technical service providers.

Candice kindly approved our changes and we are now planning our Spring soil testing and planning schedule. 

Information Products

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.