Final report for FNE24-100
Project Information
In 2024, the Carbon Sponge Hub at White Feather Farm led a network of five small farms in New York’s Hudson Valley region to continue to trial and evaluate white-grain, annual sorghum for yield and changes in soil health while also evaluating a suite of off- the-shelf field monitoring tools, referred to as the Carbon Sponge Kit. Sorghum is an underutilized crop with great potential as both human food and a climate-smart crop capable of helping sequester carbon in soil. Farmers in regions where sorghum has not been widely grown, like the Hudson Valley, can take advantage of the plant’s ability to adapt to a wide range of conditions and provide ecosystem services on farms —especially increasing soil organic carbon — while also generating revenue. Alongside Kit testing, we sent samples to two professional labs and worked with a soil scientist to analyze results. A major goal of the Carbon Sponge Hub is to help change the profile of sorghum in the U.S., including where it is grown, how it is grown and what it is used for. Our final report "Stewarding Soil Carbon with the Carbon Sponge Hub" features five case studies detailing how to incorporate annual sorghum as a cash crop on a small farm and priorities for future research and investments. This report explains our data results along with recommendations for specific tests and discussion of soil carbon stewardship with possible targets for farmers interested in regenerative agriculture with sorghum. We hosted public workshops and community volunteer days at two farms to share our progress along the way and made our report freely available via the Carbon Sponge website.
The primary objective of this proposal is for a network of small farmers in the Hudson Valley of New York to continue to work together to evaluate annual white-grain sorghum for crop yield and soil health. We are selecting five farms for this study with conditions, priorities, and needs distinctive from each other, allowing us to document a range of approaches for growing sorghum and serve as case studies in a final report. From this experience, we will be able to outline priorities for future research and investments. Sharing our process, from planting to market along with successes and failures, will support other small farmers to grow sorghum and help expand the New York Grainshed. We will continue to collect data at regular intervals with our suite of off-the-shelf tools for soil health assessment, and simultaneously sample soil and plants for analysis at two professional labs. This aids us in our secondary objective: to verify the accuracy of the Carbon Sponge Kit and make data collection recommendations for farmers wanting to balance crop yield and soil health. We will draft preliminary best practices for regenerative sorghum production in our region that is backed by farmer experience and data.
The Carbon Sponge Hub at White Feather Farm in Saugerties, NY, is supporting small farms in the Hudson Valley of New York trial climate-smart crops within a regenerative framework and employ off-the-shelf tools for self-monitoring soil. This is a farm-led initiative and a peer-to-peer farmer network for learning, sharing, and evaluating agroecological practices. With climate emergency a reality and not some far-off scenario, we are moving to adopt crops that can thrive despite extreme weather fluctuations, serve as a staple food for local populations, and last in storage for several years or more. Farmers need to balance managing crops through unpredictable weather while also cultivating soil for the future. Since 2021, we have grown white-grain annual sorghum across ten small farms and are excited by its potential to support food and soil security in our region. The focus of this grant is to continue to trial and evaluate sorghum while also validating our suite of soil-monitoring tools.
Sorghum, an ancient grain from East Africa where it remains a staple food, is heat-loving, drought-tolerant, and grows in many soil types. It has deep roots and produces a large amount of above-ground biomass, factors that increase potential for soil carbon storage. It is also a C4 plant, meaning it uses light, water, and nutrients more efficiently than most crops to fix carbon dioxide. For all these reasons, it is considered an important climate-smart crop. Sorghum can be harvested for its grain as well as its stalk juice (which can be evaporated into syrup), making it a valuable dual-purpose crop. Sorghum is not common in the Northeast, and when it is grown, farmers often use it for silage or select sorghum sudangrass for summer cover crop. The U.S. is the top sorghum producer and exporter in the world, but production mostly occurs in Kansas and Texas, and a large portion of the grain is exported to China for animal feed (Sawe; “Foreign Demand”).
There is significant opportunity to grow sorghum in new regions of the U.S., like the Hudson Valley, to take advantage of the plant’s ability to adapt to a wide range of conditions, provide ecosystem services on farms, including increasing soil organic carbon, while generating revenue. Rather than focusing on industrial scale or global revenue streams, a farmer in the Hudson Valley can integrate sorghum into a market garden and sell directly to consumers through existing farmer’s markets and CSAs. Small farmers can pool their harvests to sell in larger quantities to local bakers, restaurants, and breweries. In Heather Coiner’s “Growing Grain Handbook,” she describes the industrial consolidation of grain farming in the U.S. and challenges for smaller scale operations, but also points to opportunities for small farmers who clean, bag, and market their grain directly to a baker-miller. They can charge 6-10 times the price than if sold straight from the field and double that if sold at a farmer’s market. Entering the grain market is possible for small farmers who leverage higher prices and partners with neighboring farmers (2-4).
With the support of a Farmer Grant, we will document a year of sorghum production at five Hub farms from field preparation and planting through harvest to market. We will trial the same varieties, enabling us to consolidate harvest, and share specialized equipment, yet each farm has different physical conditions, cultivation preferences and individual needs making their story unique. We are focused on white-seeded grain sorghum because it is more palatable and nutritious than colored grains with higher tannins. We will produce a final report with five case studies to share with other small farmers interested in growing cover crops as a cash crop and entering grain production. We will outline where we think future research and investments are needed to grow and sell sorghum successfully in our region.
In addition, the grant will support the continuation and validation of our on-farm testing with the Carbon Sponge Kit. Alongside farmer testing, we will send soil and plant samples to the Cary Institute of Ecosystems Services and Logan Labs, organizations with which we already work. In consultation with Dr. Perl Egendorf, we will analyze results and evaluate the accuracy and usefulness of the Kit. We will make recommendations for specific tests and targets for farmers interested in regenerative sorghum production taking into consideration ease of use, labor, and costs. We aim to better define how sorghum is climate-smart in our region and provide recommendations for incorporating annual sorghum on small farms with equal emphasis on crop yield and soil health.
Founded in 2020, White Feather Farm (WFF) is a 66-acre certified organic, small-scale farm and educational nonprofit. We use traditional farming techniques to optimize health and environmental benefits, demystify regenerative farming practices, and preserve traditional knowledge and heirloom foods through educational programming, strategic partners, and small farm communities. We focus on innovations in soil regeneration, cultivating biodiversity, and sequestering atmospheric carbon by addressing soil health, biochar trials, organic and low till farming practices, and habitat, watershed, and wetland protection. We cultivate over 1.5 acres, providing a wide variety of organic produce, eggs, maple syrup and flowers. We market ourproduce through an on-site farm stand, and wholesale to local restaurants and food outlets. Field operations include two greenhouses, hoop houses, a sugar-shack for syrup production, rice fields, a fully equipped production barn, fruit orchard, berry arbor, four beehives and free-range chicken coops housing 50 chickens and ducks. Annual gross sales average from $20,000-$35,000. Brooke Singer was Director of Farm Innovation at White Feather Farm (2023-24) and is founder of Carbon Sponge. The Carbon Sponge Hub was hosted at WFF from 2022-2024. For this grant, WFF provided a home base, administrative support and basic farm tools. Additionally, WFF was a participating farm in the Hub. Additional labor costs, specialized tools and equipment for this project were funded by Spark of Hudson in 2024.
Cooperators
- (Researcher)
- - Producer
- (Researcher)
- - Technical Advisor
- - Producer
- - Producer
- - Producer
Research
One of the project’s main goals was the evaluation of a suite of a collection of off- the-shelf field monitoring tools (we refer to as the Carbon Sponge Kit) for gauging soil and plant health and potential for soil carbon storage. In our final report, we discuss the accuracy of the Carbon Sponge Kit and make data collection recommendations for farmers wanting to balance crop yield and soil health.
At each of the five Hub farms, we divided the sorghum production area into three equal parts and labeled Site #1-3. We tested every three months four times evenly spaced across 12 months. The first testing round was in May 2024, the second was in September 2024, the third round was in January 2025 and the final and forth testing was in May 2025. The testing was conducted by the Carbon Sponge Team and sometimes with the farmer(s), as scheduling permitted.
The Carbon Sponge Kit included: the Microbiometer, Solvita CO2 Burst, penetrometer, pH and moisture probe, thermometer, and refractometer. The Microbiometer and Solvita tests are competing commercial tests on the market for evaluating soil health. The Microbiometer is a low-cost and quick field test for microbial biomass and fungal-to-bacterial ratio that uses extraction powder to separate microbes from soil particles and detect microbe pigmentation on a membrane. The Solvita CO2 Burst test is a low-cost test that calculates microbial biomass by measuring carbon dioxide respiration. We use a penetrometer to measure compaction. We also use two soil probes, one for temperature and one for pH and moisture. pH is also recorded in the professional lab. We use a refractometer on the sorghum stalk juice to measure for BRIX on the second testing round and at harvest time, measuring for dissolved sugar.
As part of the Kit testing, we recorded site conditions like weather, irrigation, and percent soil coverage. We documented with photographs as well. The Carbon Sponge Field Technician worked with each farmer on testing days, providing consistency across the farms and the project, and were responsible for uploading the data to a shared drive. Farmers add observations in a comment section which included anything from a recent weather event or pest pressure to equipment failure.
Three soil samples were collected on each farm (from Site 1, 2 and 3) on the four designated testing days and delivered to our partner lab, the Cary Institute of Ecosystem Studies in Millbrook, NY. We collected samples at 6” depth using a composite method of 3 samples per site. We also collected a sample for bulk density analysis from the three sites per farm. The tests at the Cary Institute, conducted by Dr. Peter Groffman’s lab, included carbon and nitrogen pools, microbial biomass carbon and nitrogen, potential net mineralization, potential net nitrification, respiration, and bulk density. These lab analyses use professional “gold standards” like the chloroform fumigation and incubation method to measure microbial biomass carbon and were used to verify and measure the percent accuracy of our Kit results.
On testing day one and four we sent soil samples from each site on each farm to Logan Labs. These were also collected at 6" depth using the composite method. The soil tests at Logan included exchange capacity, percent soil organic matter, pH, nutrient levels, and soil texture. In mid-summer, we also sampled plant tissue to Logan Labs when the sorghum was beginning to bloom for analysis.
All of this data collected from May 2024 through May 2025 was used to evaluate soil and sorghum plant health across the five Carbon Sponge Hub farms. Additionally, the comparison of the Kit and lab data provided the basis for verification of the Kit tools and subsequent recommendations in our final report. The analysis and verification was led by Dr. Perl Egendorf who utilized a range of exploratory data analyses and statistical significance tests to understand relationships between soil properties, microbial community activities, and sorghum performance.
We measured and observed trends in the field that were specific to each farm as well as more general findings that were applicable to the five farms in the Hub.
The following are our main findings specific to each farm.
- Main Findings at Each Farm:
- Nimble Roots Farm: Strong Organic Matter gains from biomass inputs; success linked to reduced disturbance and residue management.
- Sweet Freedom Farm: Compost and manure inputs paid off with high Organic Matter and strong yields despite sandy soils and weed pressure.
- Foxtrot Farm: Cumulative organic inputs built fertility; should monitor nitrate to prevent leaching.
- White Feather Farm: High Calcium but low Potassium; heavy clay limits drainage and Organic Matter gains.
- Home Farm: High Phosphorus but low Organic Matter, Nitrogen, Sulfur, and Zinc; weeds limited sorghum growth.
We also had four general takeaways from the year-long study related to sorghum farming in the Hudson Valley.
Weeds were a challenge, more than insects or animals.
Regular cultivation to control weeds until the sorghum reaches about a foot in height is often necessary. We have experienced pressure mostly from grasses and plants in the Asteraceae family (specifically ragweed and mugwort) that compete for light and nutrients. Co-planting with a legume like cowpeas, which is slower growing than sorghum, or broadcasting clover when sorghum reaches a couple of inches tall could temper weeds. Investing in a cultivator to handle the weeds early (2-3 weeks after planting and again 2-3 weeks after the first cultivation) is a necessity at most farms.
Bird pressure was also a challenge and has been an issue in the past, especially when the grain is hardening and in the final phase of growth.
For smaller plots, you can deter birds using scare tape. If birds become an issue later in the season when the grain heads are formed but not fully hard (known as the dough stage), you can harvest the heads early and let them harden as they dry down in a greenhouse with air circulation before threshing. Or, cover the “doughy” grain heads in the field with corn tassel bags for the last couple of weeks of growth, checking periodically to make sure mold is not forming. For larger plots, invest in a laser scarecrow or audio deterrent boxes which we plan to test in 2026.
Kassaby sorghum plants did not mature but Korjaj was dependable.
The Kassaby in 2024 was grown from our saved seed from plants that were healthy and abundant with seed in 2023. African varieties of sorghum are adapted for specific seasonal rainfall patterns, so the variable rain patterns of the Hudson Valley can result in plants that grow very tall but fail to ripen before frost. Planting seed from a common or commercial stock that is well tested is a probable solution to this problem. If you are interested in trialing non-standard seed varieties and adapting a sorghum variety with specific, desirable traits to your bioregion, crop failure like what we saw with the Kassaby in 2024 is a risk. Sorghum has incredibly rich diversity; in the USDA-ARS (Agricultural Research Service) National Plant Germplasm System (NPGS) alone, there are 45,000 accessions. There is a lot to gain from dipping into this gene pool and experimenting, but it’s less dependable than standard, commercial seed. We did determine during this study that Korjaj variety was dependable, providing viable grain and juice and the 2025 season is confirming this as well. We are also looking for a variety that is similar to Korjaj but not as tall, or considering breeding Korjaj to grow to a shorter stature.
Mechanical equipment is not right-sized for small farms.
The biggest hurdle to increasing sorghum production in the Hudson Valley from a market garden-size plot, that can be managed with hand tools, to a 2-acre size plot or bigger is securing the proper equipment. Even if financial barriers were not an issue for small farming operations, which of course they are, U.S. manufacturers are not making farm equipment tailored to this scale. Small farmers have to “hack” and/or fabricate unique solutions or buy imported equipment from Italian or Japanese companies, where small-scale farming is better supported but sorghum is not typically grown. In 2025, we improved our ability to seed with a tractor at Nimble Roots by opting for an Italian-made precision vacuum planter. This served us much better than the large ground seeder we used the year before. Finding the right solutions for cultivating, harvesting and processing sorghum grain and juice requires capital investment, research and development, and trial and error. Success with finding right-sized solutions for sorghum harvest at a 2-acre scale will significantly increase yield potential.
We also analyzed our data to make testing recommendations for farmers to gauge soil and plant health as well think about carbon stewardship.
Organic matter from Logan Labs
This is a relatively affordable gold standard test that can be a good proxy for soil carbon, health, and fertility. We recommend taking samples for this every year, in order to get into a routine and track changes over time. If it’s not feasible to test for OM every year, this is fine. Implement a schedule that is manageable. Also, if declines in OM are found, this is part of carbon cycling. Soil organic matter (OM) takes time to build up, and can reach a threshold. We recommend embracing a long-term view; assessing the impacts of practices visually, for soils and plants, and doing what works for each unique group of farmers and each unique site. Organic Matter data can help make assessments, but should not be used in isolation.
We recommend developing a plan. We like to sample before planting in the spring to see a baseline for the year and avoid disturbing root systems. Some people recommend sampling in August. If farmers are going to couple soil analysis with tissue sampling, we recommend sampling in mid-season when there is enough plant tissue and sufficient time to add amendments, if needed. Again, we recommend doing what works for each site while attempting to be consistent.
We found some clear changes in OM over time. Notice Nimble Roots’ large increase in one year. This is rare, but we believe this happened as a result of opening up the pasture for the first time in decades and mulching the sorghum biomass in place after harvest. In contrast, at Home Farm, where fallow land was also opened up for the first time in 2024, there was no sorghum biomass incorporated and no gains in OM (rather there was a dip). At White Feather Farm’s plot, which we have been cultivating for four years, the biomass of the sorghum was incorporated into the topsoil in the Fall along with minimal winter cover cropping but there was also a drop in OM. The soils there are more clayey, more compacted and more alkaline which may be preventing gains in OM.
Moving forward, we will track the OM added to the soils at Nimble Roots to see if it is consumed by microbes and becomes incorporated into microbial biomass maintaining organic matter levels or if microbial consumption and respiration produce losses in OM in the soil. This is the nature of carbon cycling and stewardship. Carbon doesn’t build in soils in a linear fashion. We aim for net accumulation over many years, not just from one season to the next. As such, future work is necessary, including studying the development of different carbon pools (labile vs. stable; or particulate vs. mineral-associated) over time.
Microbiometer
This can be used as a proxy for OM from agronomic labs like Logan. As with other OM tests, this can be done annually, or more frequently if farmers are interested in tracking seasonal changes or impacts of different management approaches on seasonal shifts. We recommend making a plan for sampling locations and time of year, and keeping it consistent to effectively track changes.
Penetrometer, moisture, texture (with a lab, or by jar or by feel)
The penetrometer can tell us about compaction, which is linked to other physical properties like pore space, soil structure, and water retention, all of which are all important for soil health and carbon stewardship. We recommend using the penetrometer at least once per year, along with OM tests.
Soil moisture probes are generally reliable, and can be useful to assess water retention directly, along with irrigation needs. Moist soils enable active microbial life and carbon stewardship. While saturated soils support anaerobic microbes that can end up storing more carbon, these conditions may not be ideal for many plants, and are not necessarily optimal for cycling nutrients like carbon. Moisture tests can be conducted quickly and as frequently as desired.
We recommend analyzing soil texture to understand how the size particles of minerals in your soil impact the soil’s health. While texture isn’t an automatic proxy for carbon cycling, it’s important to know your soils’ textures, in order to optimally support your plants and soil microbes in doing their work. For example, sandy soils may need to be watered more frequently than clayey soils, and clayey soils might need specialized equipment for cultivation. A texture test can be done once and repeated after major inputs or tilling has occurred.
A full account of our results, along with photo documentation and charts and graphs, are included in our final report "Stewarding Soil Carbon with the Carbon Sponge Hub."
Following are the key findings from our study:
- Nutrient Status: Most farms had healthy sorghum plant tissue results. Common issues were low calcium-to-potassium ratios and site-specific nitrogen, sulfur, and zinc deficiencies.
- Soil Health Monitoring: Annual soil and tissue tests are essential. The Carbon Sponge Kit provided useful, affordable field tools, though some (like Solvita and pH meters) showed weak reliability compared to lab tests, and we do not recommend them at this time.
- Soil Organic Matter (OM): Organic matter gains varied widely. Nimble Roots saw a major short-term increase due to residue retention and high biomass inputs. Other farms saw slower changes, especially on clay-rich or compacted soils.
Based on these findings and the year-long study, we have devised clearer recommendations for farmers interested in testing to track soil and plant health. They are:
- Test Regularly
- Conduct annual soil organic matter (OM) tests (Logan Labs or equivalent).
- Pair with annual plant tissue tests mid-season to catch deficiencies early.
- Use affordable field tools (Microbiometer, penetrometer, moisture probes) to track trends.
- Build Soil Organic Matter
- Retain residues, reduce soil disturbance, and apply compost/manure if starting off with very low organic matter or difficult texture like high clay or high sand.
- Use N-fixing cover crops to build fertility naturally.
- On sandy soils, prioritize organic inputs and moisture management.
- On clay soils, improve structure with broad forking or light tillage, plus compost amendment and drainage management.
- Track Physical Properties
- Use a penetrometer once per year to monitor compaction.
- Measure soil moisture regularly to ensure microbial activity.
- Assess soil texture at least once (repeat only following major disturbance or addition of amendments).
- Long-Term Carbon Stewardship
- Focus on building stable carbon pools (via cover crops, living roots in the ground all year, residues, and organic inputs).
- Expect slow visible changes; track trends over years, not just seasons.
Education & Outreach Activities and Participation Summary
Participation Summary:
On July 27, 2024, Brooke Singer led a Carbon Sponge workshop at White Feather Farm in Saugerties, NY, during their one-day Soil Fest. During this 2.5-hour free, hands-on workshop, participants learned about the Carbon Sponge Hub and how to design a carbon sponge. Singer presented the Carbon Sponge Kit and demonstrated it in the field. There were 12 participants.
On September 14, 2024, also at White Feather Farm in Saugerties, NY, Carbon Sponge hosted a 3-hour workshop with Atina Foods of Catskill, NY. During this workshop, participants learned about our hub of small farmers collectively trialing climate-smart crops, like sorghum, and monitoring soil health. Then Atina Foods shared different ways to prepare sorghum grain to make sorghum dosas, roti, and other flatbreads of Indian origin. There were 25 participants and tickets were sliding scale from $0-20.
On October 5th, 2024, Carbon Sponge participated in Sweet Freedom Farm's sorghum harvest in Millerton, NY. Sweet Freedom Farm is currently one of the 5 Carbon Sponge Hub farms. Brooke Singer set up a table with the Carbon Sponge Kit, Guidebook, and handouts for people to learn about the project and how sorghum is climate-smart. She discussed with attendees what an agroecology framework is that centers sorghum and shared several DIY tools for testing soil and plants for soil and plant health. The audience was a mix of people interested in farming, food, and ecology, as well as experienced farmers. There were approximately 75 people in attendance.
Brooke Singer presented Carbon Sponge at a conference on June 25, 2024, in Windsor, Ontario, called FEMeeting: Women in Art, Science and Technology to an audience of 200. Brooke Singer also presented Carbon Sponge via online video conference to an art, science, and technology faculty research group (15 members) at the National Autonomous University of Mexico (UNAM) on August 26, 2024. Brooke Singer joined Northeast SARE's Candice Huber on August 1 for an online webinar titled "Soil Health and SARE Grants" hosted by Sullivan County's Cornell Cooperative Extension (CCE).
Brooke Singer presented Carbon Sponge at CalTech for a one-day symposium, "Defining a Visual Practice Lab," that explored the essential role of diverse visual practices in driving innovative art-science-society collaborations. This symposium took place on April 11, 2025. Lastly, Brooke Singer presented the work of the Carbon Sponge Hub at the Hudson Valley Grain School in Poughkeepsie, NY, on February 25, 2025, organized by Cornell Cooperative Extension and Glynwood Center for Regional Food and Farming.
Lastly, there were two Carbon Sponge Culinary Workshops in March 2025 with support provided by the Spark of Hudson. One took place at Knead Love Bakery with Sarah Magid in Greenpoint, Brooklyn, with a focus on gluten-free baking with sorghum. The other occurred at the Brooklyn Granary and Mill in Gowanus, Brooklyn, with baker and grain researcher Katie Phelan. She lead participants through methods and techniques for working with sorghum grain, syrup, and flour in pastry doughs and layered desserts. Brooke presented about the Carbon Sponge Hub and the climate-smart aspects of sorghum prior to the culinary artists' demonstrations at both of these events.
Press:
Making the Case for Sorghum, Ambrook Research, June 21, 2024
The Soil-obsessed Artist brings Sorghum to New York Farms, ScienceLine, October 21, 2024
Can an Ancient Grain Support Soil Health in New York, Times Union, April 1, 2024
Sequestering Carbon is not Just a Science but an Art Too, Modern Farmer, April 3, 2024
Learning Outcomes
Changes in knowledge, attitude, skill and/or awareness:
Annual sorghum as a climate-smart plant in New York;
Annual sorghum as a cash crop in New York for both grain and juice for human consumption;
Integration of grain in primarily diversified vegetable small farms;
Grain harvesting and processing techniques on a small scale;
On-farm, rapid field testing that is inexpensive yet informative for gauging soil and plant health;
Analyzing professional laboratory reports with the help of an agronomist;
Coupling soil and plant testing for an integrated, agroecological framework;
Strength of peer-to-peer farmer networks for problem-solving, equipment sharing, and increasing profitability through collective marketing of products.
Project Outcomes
The major project outcomes include: improved testing recommendations for small farmers wanting to track soil and plant health, especially in relation to growing sorghum and soil carbon stewardship; the ability of large soil organic matter increase from year one to year two when growing sorghum using specific cultivation practices; a better understanding of the top challenges for growing sorghum in the Hudson Valley for small farmers, like weed pressure; and strengthening of ties between small farmers interested in sorghum production in the Hudson Valley. Our report "Stewarding Soil Carbon with the Carbon Sponge Hub" provides more details of all these outcomes, along with others.
Our biggest success story was at Nimble Roots Farm in Catskill, NY. They experienced a very large gain in soil organic matter (nearly 2%!) from April 2024 to May 2025 during this study. This is the clearest sign that our methods of growing sorghum are building soil carbon. The methods include residue retention, mulching in place, and reduced soil disturbance.
Following are the key findings from our study:
- Nutrient Status: Most farms had healthy sorghum plant tissue results. Common issues were low calcium-to-potassium ratios and site-specific nitrogen, sulfur, and zinc deficiencies.
- Soil Health Monitoring: Annual soil and tissue tests are essential. The Carbon Sponge Kit provided useful, affordable field tools, though some (like Solvita and pH meters) showed weak reliability compared to lab tests, and we do not recommend them at this time.
- Soil Organic Matter (OM): Organic matter gains varied widely. Nimble Roots saw a major short-term increase due to residue retention and high biomass inputs. Other farms saw slower changes, especially on clay-rich or compacted soils.
Based on these findings and the year-long study, we have devised clearer recommendations for farmers interested in testing to track soil and plant health. They are:
- Test Regularly
- Conduct annual soil organic matter (OM) tests (Logan Labs or equivalent).
- Pair with annual plant tissue tests mid-season to catch deficiencies early.
- Use affordable field tools (Microbiometer, penetrometer, moisture probes) to track trends.
- Build Soil Organic Matter
- Retain residues, reduce soil disturbance, and apply compost/manure if starting off with very low organic matter or difficult texture like high clay or high sand.
- Use N-fixing cover crops to build fertility naturally.
- On sandy soils, prioritize organic inputs and moisture management.
- On clay soils, improve structure with broad forking or light tillage, plus compost amendment and drainage management.
- Track Physical Properties
- Use a penetrometer once per year to monitor compaction.
- Measure soil moisture regularly to ensure microbial activity.
- Assess soil texture at least once (repeat only following major disturbance or addition of amendments).
- Long-Term Carbon Stewardship
- Focus on building stable carbon pools (via cover crops, living roots in the ground all year, residues, and organic inputs).
- Expect slow visible changes; track trends over years, not just seasons.
Our future work should include testing the different carbon pools (particulate organic matter vs. mineral-associated organic matter) to understand the large soil organic matter gains at Nimble Roots Farm over time.
We believe the five case studies in the report will benefit any small farmer interested in growing sorghum. Our evaluation of different testing tools and laboratory results will benefit small farmers wanting to learn more about soil and plant testing, especially within an agroecological framework, and how to incorporate them into their practices without breaking the bank.
We accomplished what we set out to do in our study (i.e., comparing sorghum production at 5 small farms in the Hudson Valley) and answered our primary question about the validity of our on-farm testing and which tests are worth investing our money and time. There is still more work to be done to develop our framework for soil carbon stewardship. Moving forward, we are particularly excited to investigate the gains in soil organic carbon at Nimble Roots Farm and utilize testing protocols to understand the carbon fractions, or the percentage of stabilization versus cycling. We are also more experienced with running a hub, coordinating equipment and other needs across farms, and collaborating to bring products to market together.