Carbon Sequestering in Farm Country Made Easy


The Climate Summit in Paris in December 2015 initiated the 4 per Thousand Program.  The strategy of this program is to sequester carbon in soils of the world at the rate of 0.4% per year in the top 16 inches of soil. 


Bill Brandon

With the introduction of perennials like switchgrass into their crop management plans, farming carbon credits and energy may prove a valued product for farmers to diversify into.”

Fields of Potential

U.S. croplands pose great potential to make such goals realistic. A cornfield for example would take in about 8 tons of CO2 per year per acre.  To reach the .4% goal, 64 pounds of CO2 per acre needs to be sequestered. However, this carbon must be stable and remain in the soil over very long periods of time.

Part of this loss comes from traditional tilling practices. Intensive tillage followed by fallow fields for the production of corn and small grains have resulted in a loss of more than half of soil’s original carbon content over time.

A study at the Northern Great Plains Research Laboratory using spring wheat cultivated with traditional tillage practices showed how differences in cropping systems affect soil structure and soil carbon. In the traditionally tilled spring wheat, the soil had 14% water-stable aggregates, and the carbon in the top 3 inches of soil measured 6.6 tons per acre.  No-till continuous cropping of spring wheat/winter wheat/sunflowers increased soil quality by comparison. No-till soil had 47% water-stable aggregates, and the carbon measured 9.6 tons per acre.

This soil carbon is still not stable though.  The plant litter and root structure left as the crop residue will be decomposed by bacteria, which convert only 20 – 30% of the carbon into new cells with 70-80% being released into the atmosphere.  These bacteria die quickly as new bacteria replace them. The dead bacteria are consumed by nematodes and protozoa that live in the soil and release nitrogen and other nutrients the plants need in a form the plant can use.  

We are progressing but the carbon content in the top 3 inches of that system is still not stable.  It also does not account for the Nitrous oxide released by this decomposition and nutrient release process.

What Can Save the Prairie?
Prairie Grass

A five-year on-farm study by the Agricultural Research Service evaluated switchgrass for ethanol production. The study encompassed 10 farm fields in Nebraska, South Dakota, and North Dakota. The fields were located in marginal land areas that would have qualified for the CRP.  

In the study, they found soil organic carbon increased across all sites at a rate of 980 pounds per acre per year within the top 12 inches of that soil.  In Nebraska in particular, where four sites were sampled to a depth of 48 inches, carbon increased at an average rate of 2,590 pounds per acre per year.  

These were average increases measured over 5 years and represent actual stable sequestration of carbon.  At the end of five years, 6.5 tons of carbon was stored.  The permanent deep roots of switchgrass supported fungi, which annual crop roots cannot do.  Even with a cover crop, biological activity takes place primarily near the surface by bacteria.  The fungi are 40-55% efficient in converting carbon to cells and as a multi-cell structure they can live a long time and sequester carbon in a stable manner.  

The temporal cycle of carbon in the topsoil with bacterial dominated ecosystems is big, but fast.  That is, it contains a lot of soil carbon that is converted into CO2 quickly, thereby limiting its sequestration value.  Carbon in the deep subsoil dominated by fungi is not so big, but slow to be converted resulting sequestration times of many, many, many years.

It is my understanding that the Ecological Services Market Consortium will initially be assigning a credit value to a cover crop, no till practice.  We will have to wait to see how they arrive at their figures.  Whatever their final calculations are, they will not match the sequestration capable from a perennial, deep-rooted energy crop. 

From another revenue angle, switchgrass can produce twice the biomass of corn stover per acre.  After establishment, a stand can remain productive for over 10 years before it needs to be replanted.  

Sequestering new carbon in the subsoil at a modest rate of .8 tons per acre for the first year (the equivalent of 2.9 tons of CO2 when released and not counting the reduction of nitrous oxide emissions), carbon credits at $54/acre ($15/ton CO2) would equal $43 and increase after that. Add to that about $35/ton value as energy at 9 tons per acre, or $315 per acre. 

Harvesting costs are about $25 per acre or less with purpose designed machinery.  Up front planting costs are more. Some fertilizing to get 9 ton per acre will be necessary, but after that little ongoing costs are incurred. These are conservative estimates and very favorable compared to corn economics. (Other figures have calculated far greater carbon sequestration.  There is no set calculated standard.)

With the introduction of perennials like switchgrass into their crop management plans, farming carbon credits and energy may prove a valued product for farmers to diversify into.

Primary source:   



Opportunity Deep in the Dirt of Cover Crops

Part 3 of our “Advanced Farming Opportunities” Series with Bill Brandon

By Bill Brandon

In this series’ previous installment, I discussed the above ground significance of cover crops. In this part I will review the below ground significance.  

This is all about microbial ecology.  Without soil microbes, plants would not grow.  Over the years of following ‘industrial’ methods recommended by large agricultural suppliers and agricultural schools and extension services, post WWII farming practices have disrupted ‘good’ microbial ecology.  Chemical fertilizers and accompanying methods created the ‘first green revolution’ that greatly increased productivity. After many years, we are learning that it also had a down side.

Radical, and often uninformed, activists have blamed famers for a linty of transgressions, lumping them in with the institutional and corporate interests that gave farmers the template for ‘modern farming’.  

The ‘new modern farming’ will need to take what has been learned to build a system that better serves our whole population and the environment which plants, animals and people must live in.  Here we must start with understanding soil organic material (SOM).

SOM is composed of:

  1. The ‘living’, all microbes, fungi, nematodes, protozoa, etc. that live in the soil and carry out metabolism, taking in ‘food’ and giving off CO2 or methane.
  2. The ‘recently dead’, plant material that has recently died and animal excrement that exist primarily near the surface.  If this material, provided to us by the sun through photosynthesis, were not broken down into energy and ‘recycled’, we would be in compost from here to the stratosphere.
  3. The ‘long term dead’, organic materials that resist decomposition and remain sequestered in the soil for long periods of time. Some small amount of these materials are man made and are often called ‘forever chemicals’ and are often toxic.

Bacteria and fungi are the two primary ‘decomposers’ of the ‘recently dead’.  They are in competition for food and some fungi are somewhat antibiotic to give themselves an advantage.  You might ask what difference it makes whether bacteria or fungi provide the decomposition of SOM and recycling of nutrients. It is generally thought that fungi dominate forests while bacteria dominate tilled farmland for very good reasons.

SOM RoleNematodes and protozoa eat the bacteria and excrete ‘chelated’ nutrients that can be taken up and used by plants.  Fungi, however, are multi-celled structures that directly deliver chelated nutrients to the plant root, which it has surrounded.  
Nutrient RequirementsBacteria are very resilient, going for long periods of time without food.  They exist dormant and then come ‘alive’ when conditions change.  Fungi need a continuous source of food.  When a field is plowed or tilled the structure of the fungi is torn apart and they have a hard time regenerating, while the oxygen supplied to bacteria makes them eat and multiply like crazy.  In the winter, food becomes scarce for fungi if their entire neighborhood is an annual plant.  
Carbon Conversion PerformanceBacteria are poor ‘carbon converters’, using only 20 – 30% of the carbon of the ‘recently dead’ to produce more cells, while 70-80% is released as CO2 into the soil and then into the atmosphere.  Mycorrhizal fungi convert 40 – 55% of their food source into new cells, thereby increasing living SOM faster.  
Nox Conversion PerformanceBacteria contain more nitrogen than fungi but when converted by nematodes and protozoa not all is converted into a form the plant can use; some is converted into Nox. Fungi use different chemical routs to make nitrogen available to plants and little or none is converted into Nox.

A well developed microbial ecology adds to soil fertility and larger amounts of SOM’s living components promote water retention in all the micro passageways created by the microbial community that is also used for oxygen access to the plant root.  Ecological offset credits will strongly focus on the amount of converted and stored CO2 in the soil and how much Nox (CO2 equivalent) is reduced. Restoring fungi to soils will greatly enhance this ‘carbon storage and offset’ component of the offset credit.

A Busy Person’s Intro to Cover Crops

Part 2 of our “Advanced Farming Opportunities” Series with Bill Brandon

By Bill Brandon

The big news is that the Ecological Systems Market Consortium was formalized in January 2020.  This is not a government program, it is a non-profit supported by major agriculture and food companies from Cargill to McDonald’s. 4

Their first area of focus will be cover crops for the Midwest.  They are targeting a value of $15/ton of CO2e sequestration in soils plus other sustainable objectives such as reduced soil erosion, preventing fertilizer pollution into waterways and building soil nitrogen and nutrients.  There will be a variety of practices that contribute to the ultimate value of an offset credit. The farmer should view this program as an opportunity to do the right thing while making money and/or reducing costs by doing it.

Objectives of cover crops  

There are five basic reasons for using cover crops. 

  • Prevent soil and nutrient erosion
  • Produce a marketable crop
  • Add nutrients to the soil
  • Maintain a good soil microbial ecology
  • Sequester CO2 and reduce Nox (a powerful greenhouse gas) and CO2 emissions from the soil

It has been pretty well established that a cover crop with roots does a better job in preventing erosion than loose surface material.  Planting a cover crop costs money and it is reasonable to look for a return on this investment. There is always a long-term return in healthy soil, but financial decisions must often be made on a year-to-year basis.

There are also cash advantages for cover crops.  Adding nutrients to the soil for the next growing season is a reduction of future expenses.  If this is your objective, red clover is hard to beat as a cover crop. It has a large amount of protein in its leaves, which is the source of nitrogen returned to the soil.  If a marketable product is your objective, an oil seed crop like any variation of pennycress is a good choice for the upper latitudes (generally above 35 degrees). It can be sold as a high value fodder for animals or the seeds can be sold to a processor, most likely a biodiesel refiner.

Another option will be selling ecological or carbon credits into the new market being set up.  This option will be discussed further in our next installment.

Why Do We Grow What We Grow

By Bill Brandon

The answer is probably just TRADITION!  Tradition is founded on some practical foundation and wrapped in social and economic ties and laws, etc.  It is hard to break from tradition. Cost is associated with such a change.  

Farming is based on change though. When our ancestors started farming, it changed society. Most people would say for the better. They raised their basic foodstuffs of grains, fruits, and vegetables.  As our society advanced, we added domesticated animals, which sometimes added to our harvest demand, as we grew feed for them. Farming rooted itself in progress and advancement taking over several core industries for centuries.

By the 19th century in America, farming was a backbone industry for daily life’s many needs.  They provided food, of course, for themselves and those working in cities and factories.  They were also the core providers of horses and mules, the powerful farm machines and transportation vehicles of that time. These same machines helped create their own fuel with the roughage and grains used to feed them throughout their day of labor.  Food, transportation, and fuel were the sources of income a farmer could count on.

This changed with the introduction of the internal combustion engine and the development of the oil industry. Farmers adopted tractors, and instead of raising and selling ‘fuel’ they now bought it from oil companies.  The importance of the farmer started to decline in America. While the country roared in the 20’s, the farmer just held on. By the end of WWI, farmers had pretty much completely lost the transportation and ‘fuel’ market. Now they were highly reliant on a commodities market.

Today, many farmers are tied to this format. They are stuck between corporate input suppliers and corporate commodity buyers. These buyers, in turn, distribute low cost products in the form of processed foods and animal feed.  This format has drained rural farm communities of their wealth and a connection to their own community’s needs. While some brag about American agriculture ‘feeding the world’, rural food deserts are common with lack of access to healthy food options.  

Those who are concerned about poor Americans diets leading to  chronic health issues often chastise farmers for ‘farming the subsidies’.  This is a simplified criticizing concept of the problems of farmers and rural economies. However, many, including farmers, feel we need to pivot the Nation’s farm format and structure.

Farming is a critical industry in any country and deserves special support to keep it healthy and productive.  The question is to what end. What factors of agriculture deserve support? Which ones serve the nation and food consumers on the whole and not only corporate food processors and input suppliers? 

The EPA has estimated that in 2017 the agriculture economic sector (including farms and supporting business) accounted for 9% of total U.S. greenhouse gas emissions.*  Others say this is actually 37% because some areas are undercounted. Undercounted may be partially true because, for example, the production of fertilizers, which releases significant CO2, is included in the ‘Industrial sector’.

Critics are not completely negative about agriculture’s ability to become more sustainable. Peter Lehner, who authored the “Agriculture” chapter of “Legal Pathways To Deep Decarbonization In The United States, stated “The good news is we can actually reach carbon neutral agriculture pretty soon, and we can reach it in a way that is profitable for the farmers and for the communities they live in.”**

Some believe that farms can even become carbon negative, sequestering more CO2e than they release. At the same time, they can once more supply local fresh produce year round without relying on food from distant growers.  It will, however, require a pivot from business as usual.  

To advance this goal, we are running a series of blogs looking at factors that might advance this pivot and return more industries like energy back to rural farm communities.