Lab tests found that biochar, a charcoal-like material made from wood waste, reduced methane produced by cow stomach microbes by 84% in a high-forage diet. Nitrate alone cut it by 70%. Combining the two did not beat either one alone, according to Gram Research analysis of this 2026 in vitro study.
Cows release methane, a gas that warms the climate and wastes some of the energy in their feed. A new lab study, reviewed by Gram Research analysis, tested whether biochar, a charcoal-like material made from wood waste, could reduce this gas. Researchers mixed the material and nitrate, a compound that can also reduce methane, with fluid taken from cow stomachs and measured the gas produced. Biochar cut methane by 84% in a high-forage diet, and nitrate cut it by 70%. Using both together did not work better than either one alone. Because the test was done in flasks rather than in live animals, these results are an early step and not proof that farms can use these methods yet.
Key Statistics
A 2026 in vitro study published in JDS Communications found that biochar reduced methane production by 84% in a high-forage diet using rumen fluid from cows.
The same 2026 laboratory study found that nitrate lowered methane production by 70% in a high-forage diet, while combining nitrate and biochar did not lower methane more than either additive alone.
According to research reviewed by Gram, adding almond hulls as a forage substitute did not change methane production in the 2026 flask-based experiment.
The Quick Take
- What they studied: Can wood-based charcoal (biochar) and nitrate, alone or together, reduce the methane gas that cow stomach microbes produce while digesting feed?
- Who participated: This was a laboratory experiment, not a study of live animals. Researchers used fluid taken from cow stomachs, placed in small sealed flasks with different feed mixes. The exact number of flasks was not stated, but the test was repeated in three separate rounds.
- Key finding: Biochar reduced methane by 84% and nitrate reduced it by 70% when cows were fed a high-forage diet. Combining the two did not produce a bigger drop than either one alone.
- What it means for you: These results are promising for future climate-friendly farming, but they come from lab flasks. They do not yet tell farmers or pet owners what to feed animals, and any changes to animal diets should be discussed with a veterinarian or animal nutrition expert.
The Research Details
Researchers set up a controlled lab experiment using small 200-milliliter flasks filled with buffered rumen fluid, which is the liquid from a cow’s first stomach where microbes break down plant material. The flasks were kept warm and without oxygen for 24 hours to mimic conditions inside the stomach.
The team tested low-forage and high-forage diets, each with and without biochar and with and without nitrate. They also tested a low-forage diet where almond hulls replaced part of the forage, again with and without biochar. The experiment was arranged in three separate rounds, with duplicate flasks for each treatment, which helps reduce the chance that a single odd result drives the conclusions.
Gas was collected in special balloons that do not let air leak out, and a sensor measured how much methane was present. The researchers also measured digestion of fiber, fatty acids produced by microbes, and nitrogen levels, which together show how the microbes were behaving.
Testing in controlled flasks lets scientists isolate the effect of each additive without the many other factors present in a living animal. This makes it easier to see whether biochar or nitrate actually changes microbial methane production. Repeating the test in three rounds also helps show whether the results are consistent rather than a fluke.
However, flask tests are a first screening step. They cannot show how animals would respond over weeks or months, whether animals would eat the additives, or whether the effects would last under real farm conditions.
The study used a randomized design with repeated rounds and duplicate samples, which are good signs of careful work. Statistical analysis accounted for the rounds, which strengthens confidence in the comparisons.
The paper does not clearly state the total sample size, so readers cannot easily judge the full scale of the experiment. It was also published in a newer journal whose impact factor is not established, and the work has not yet been widely replicated. Readers should treat these findings as early evidence that needs confirmation in live animals.
What the Results Show
The clearest result was that biochar alone reduced methane production by 84% in the high-forage diet. Forage is the plant-based bulk of a cow’s diet, such as grass or hay, and high-forage diets tend to produce more methane than diets with more grain. This suggests biochar may be especially useful in the diets that create the most methane.
Nitrate alone also lowered methane production, by 70% in the same high-forage diet. Nitrate appears to give microbes an alternative way to use up hydrogen, a gas that methane-producing microbes normally use. When microbes use nitrate instead, less hydrogen is left over to make methane. Nitrate also reduced how well fiber was broken down and changed the balance of fatty acids made by microbes.
The researchers expected that biochar and nitrate would work even better together, but they did not. The combination did not lower methane more than either additive alone. The team suggested that biochar may hold nitrate in a way that helps it be converted, and that a longer period for microbes to adjust, and lower doses, might reveal positive effects that this short test missed.
Adding almond hulls as a forage substitute did not change methane production. This is useful to know because it suggests that this type of feed swap does not add or reduce methane on its own in this setup.
Biochar and nitrate affected ammonium levels in the flasks in ways that support the idea that biochar helps nitrate break down. Testing showed very little nitrate or nitrite left after 24 hours, which suggests the nitrate was fully used up by the microbes.
Nitrate lowered the ratio of acetate to propionate, two fatty acids that microbes produce during digestion. This shift matters because these fatty acids are part of how cows get energy from feed. The almond hull diet increased several fatty acids while reducing longer-chain ones.
Microbial nitrogen production, a measure of how much protein microbes make, did not differ among the treatments. This is reassuring because it suggests the additives did not harm the microbes’ basic growth in this short test.
Nitrate has been studied for years as a way to lower methane in livestock, and many studies have found it can reduce methane when used carefully, although high doses can be risky for animal health. Biochar has been explored more recently as a material that may help capture gases and support microbial activity in soil and animal systems. This study connects these two lines of research by testing them together for the first time in this setting.
The results for nitrate alone are consistent with earlier work showing it can cut methane. The biochar results are newer and suggest it may be a strong methane reducer in lab conditions, though earlier research on biochar in animals is still limited.
The biggest limitation is that the study was done in lab flasks, not in living cows. Flask conditions cannot fully reproduce the complex environment of a real stomach, including how animals eat, chew, and absorb nutrients over time.
The researchers only ran the test for 24 hours. They noted that microbes may need longer to adjust to these additives, so the short timeframe may have hidden effects that appear with extended use.
The doses used were relatively high, and the researchers said lower doses should be tested. High doses of nitrate can be harmful to animals, so the levels that work well in flasks may not be safe or practical for real animals.
Finally, the total sample size was not clearly reported, and the study has not yet been repeated by other scientists. More research is needed before drawing firm conclusions for farms.
The Bottom Line
Confidence in the lab results is moderate: the methane reductions from biochar and nitrate are clear in this controlled test, and the findings agree with earlier nitrate research. Confidence that these results will translate to live animals on farms is currently low, because the study did not test real animals. Researchers should next test lower doses over longer periods in living animals, and check that animal health and milk or meat quality are not harmed.
Researchers studying climate-friendly livestock, animal nutrition scientists, and agricultural policymakers may find this useful as a starting point. Farmers and feed companies may want to watch for follow-up studies in live animals. Pet owners, home gardeners, and general readers do not need to change anything based on this study alone, and people should not try to give cows, goats, or other animals biochar or nitrate supplements without expert guidance.
Lab-based findings like these usually take several years to move into animal trials and then into farm use. Animal studies typically need months of feeding trials, and any product would also need safety checks and regulatory approval before reaching farms. Consumers should not expect to see these methods in food products in the near future.
Frequently Asked Questions
Can biochar reduce methane from cows?
Lab tests published in 2026 found that biochar reduced methane production by 84% in a high-forage diet when using cow stomach fluid in flasks. These results have not yet been confirmed in live cows, so farm use is still unproven.
How does nitrate lower methane in cattle?
Nitrate gives stomach microbes an alternative way to use up hydrogen, so less hydrogen is left to make methane. In a 2026 lab study, nitrate cut methane by 70% in a high-forage diet, though high doses can be harmful to animals.
Does combining biochar and nitrate work better for reducing methane?
In a 2026 lab study, combining biochar and nitrate did not lower methane more than either one alone. Researchers suggested that longer microbial adjustment periods and lower doses may be needed before any added benefit appears.
Is biochar safe to feed to livestock?
This study tested biochar only in lab flasks, not in living animals, so its safety for livestock has not been established. Animal health effects must be studied in live animals before any feeding recommendations can be made.
Want to Apply This Research?
- If you use the app to log food or sustainability goals, you can track how often you choose plant-forward meals or buy dairy and beef from farms that publicly report methane or feed practices. Log these choices weekly and set a simple target, such as three plant-forward meals per week.
- Use the app to explore meal swaps that lower the climate footprint of your diet, such as eating more beans, lentils, and vegetables, or choosing smaller portions of beef and dairy. Keep these swaps realistic and enjoyable so they last.
- Over several months, review your logged meals and climate-related choices in the app to see patterns. Watch for new peer-reviewed studies on livestock methane and feed additives, and update your choices only when results are confirmed in live animals and by more than one research group.
This article summarizes a laboratory study that tested methods in flasks of cow stomach fluid, not in living animals. Results may not apply to real farms, and this information is not advice for feeding animals or for personal health decisions. Consult a veterinarian, animal nutritionist, or qualified expert before making changes to animal diets or supplements.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.