How Oxygen and Cultivation Impact Glyphosate Breakdown

By Tim Scrivener
Published November 5, 2025 on Farmers Weekly

The breakdown of glyphosate in soils is fundamentally influenced by three key factors: oxygen availability, soil biology and the presence of cultivations.

Glyphosate is an effective tool for controlling weeds and terminating cover crops, but its persistence in soil has raised concerns about environmental impacts and soil health. 

Rothamsted Research microbiologist Prof Andrew Neal explains that oxygen availability within the soil is essential for effective glyphosate degradation.

Carbon-phosphorus bond

Glyphosate contains a strong carbon-phosphorus bond – a chemical bond that is rarely found in nature and requires substantial energy to break. 

There is uncertainty around the number of soil microorganisms that possess the enzymes capable of cleaving this bond, but these microbes depend on high availability of oxygen to do so efficiently.

“Microscopic pores are extremely important to oxygen movement and availability. The greater the pore space and organic matter, the more oxygen can circulate.

“That’s vital for the microbes responsible for breaking down glyphosate,” he says. 

In well-aerated soils rich in biological activity, glyphosate can be metabolized relatively quickly. But in compacted or oxygen-poor soils, it can persist for months.

On-farm trial

In an on-farm trial led by Rothamsted Research, in collaboration with the University of Nottingham, cultivated plots treated with glyphosate fell below detection limits within 12 days post-glyphosate application. 

In uncultivated soils, where pore space and aeration were lower, glyphosate persisted for around 30 days.

The findings reveal that soil management has a clear effect on glyphosate longevity.

Soils with better biological activity, organic matter, and oxygen flow support faster microbial degradation.

Cultivation can enhance oxygen movement and lead to more aerated soils which support biological function. However, repeated intensive tillage can damage the long-term pore networks.

“It shows that nothing you do to soil comes without consequence,” says Andrew.

Staffordshire farmer Tim Parton, who hosted the trial at Brewood Park Farm near Cove has long focused on biological and nutritional farming. 

He has eliminated use of fungicides, insecticides, and growth regulators, instead focusing on soil and crop health. 

However, Tim admits glyphosate still has a role on his farm, mainly for desiccating cover crops but this is used sparingly.

“I see glyphosate as a tool in my armory, but I want to keep its use to an absolute minimum,” he says. 

Tim refuses to use glyphosate as a pre-harvest desiccant, especially on milling wheat destined for human consumption.

“We’re living organisms ourselves. I wouldn’t want to eat food that’s been sprayed with glyphosate just before harvest,” he says. “That’s madness.”

Tim’s regenerative system revolves around cover cropping, which helps maintain living roots, improve soil structure, and feed soil microbes. 

When conditions are right, covers are successfully terminated mechanically by rolling on a frost with a crimper roller. 

“This maintains ground cover, suppresses weeds, and conserves soil moisture, but we all know the UK’s maritime climate doesn’t always allow for this.

“Glyphosate remains a backup when frost or timing are not in our favor,” he says.

“Everything you do to soil has side effects. The challenge is to choose the action with the least damaging impact, so the soil biology can stay alive and functioning.”

Four scenarios

To study how different management methods affect glyphosate breakdown, the trial was established in a field of spring lupins following a cover crop.

Four different treatments were compared to destroy the cover crop:

1. Crimper roller (farm standard when establishing spring crops after cover crops)
2. Glyphosate (2 liters/ha of glyphosate, made up to 3 liters/ha with additions of fluvic acid, citric acid and molasses)
3. Tillage (two passes of carrier discs working the soil down to 10cm)
4. Tillage to 10cm + glyphosate (3 liters/ha of glyphosate applied before cultivation)

Fueling the biological breakdown 

To stimulate microbial breakdown and enhance uptake into the plant, Tim adds citric and fulvic acids, and molasses to tank mixes of glyphosate.

“Citric acid lowers pH which glyphosate works more effectively at. 

“Fulvic acid also helps lower pH and acts as a powerful chelating agent, enhancing glyphosate uptake into the weed for a more effective kill,” he says.

Molasses provides a readily available carbon source, to feed the microbes that help degrade glyphosate residues.

“We have to work with biology, not against it. The more we understand how our actions influence what’s happening below the surface, the better decisions we can make for our soils, crops, and the environment.”

X-ray tomography

To better understand how these management practices influenced soil structure, and in turn glyphosate breakdown, soil cores were collected and transported to the University of Nottingham to image soil structure using x-ray computed tomography.

Visualizing the structure of soil following 14 years of no-till management showed a well-connected network of pores, root channels, and worm burrows – a testament to Tim’s biological farming approach.

This created the ideal soil conditions for oxygen movement and microbial activity, to breakdown glyphosate effectively. 

In the tillage scenario, the soil appeared more open and “fluffy” in the top few inches with increased pore space and oxygen diffusion.

However, a week later, this fluffy structure had collapsed. In this scenario, after initial loosening, the pore space decreased, and oxygen movement became restricted again. 

“The tillage area did initially have high porosity, but it soon slumped after a few weeks.

“Whereas the direct-drilled area was maintained at the same high porosity throughout, which allows the oxygen to enter the soil and breath,” says Tim.

What’s more, the tillage plot, without glyphosate was a complete disaster.

“This plot got overcome with weeds due to the excess tillage. The soil dried out far more and the crop of lupins failed.

“The direct-drilled crop did 1.2t/ha, which was good considering the dry spring,” says Tim.

Soil structure and cultivation 

Soil structure had a direct impact on how long glyphosate remained in the soil. In cultivated plots, glyphosate was broken down rapidly – falling below detection limits within 12 days. 

In uncultivated soils, where pore space and aeration were lower, glyphosate persisted for around 30 days.

Tim feels the results from this experiment would reveal totally different findings on a “dead” soil with very poor biology as a result of over use of nitrogen with little organic matter input and intensive tillage. 

“With my soils being so microbially active, the glyphosate can be broken down very quickly. However, in a poor anaerobic soil, the glyphosate would hang around for a long time in the right conditions.

“This is why having a working soil is so important,” he says.

Therefore, managing soils for structure, stability, and aerobic microbial activity can not only accelerate the breakdown of glyphosate but supports overall system resilience.

“Healthy soils breathe. When you maintain pore space, organic matter, and biological activity, the soil can process inputs naturally – including glyphosate. “That’s the foundation of sustainable soil management,” concludes Andrew.

Read the original article on FarmersWeekly.com »

Say No to Glyphosate

By Dina Akhmetshina, Federal Legislative Advocate, U.S. PIRG
Published July 29, 2025 on PIRG

What is glyphosate?

Glyphosate is a broad-spectrum herbicide commonly used by farmers, groundskeepers and gardeners to kill weeds and undesirable plants or grasses. 

In recent decades, glyphosate has been linked to some serious health risks, including cancers like lymphoma. Despite this, glyphosate continues to be used on parks, playgrounds, fields and yards across the nation. 

Glyphosate is the most commonly used herbicide in the U.S.

With 280 million pounds being sprayed across nearly 300 million acres of farmland every year, glyphosate remains the most widely used herbicide in the nation. 

For perspective, that means every year literal tons of glyphosate are sprayed on an area roughly equal to the states of Texas, Kansas and Wyoming combined. 

From corn to soy to canola, this pesticide is used on many of the crops that have become staples of our diet and food system. 

But when sprayed, the chemical doesn’t always stay entirely on the plant, or even the farm. The herbicide can make its way into our waterways as runoff pollution, ending up in rivers, lakes and streams, including those that serve as drinking water sources. 

As a result, trace amounts of glyphosate have turned up in many foods and beverages that Americans bring home from the grocery store every day. 

Four out of five Americans tested were positive for detectable traces of glyphosate

Companies like Bayer, the producer of the popular glyphosate-based herbicide Roundup, frequently dismiss concerns about the chemical’s prevalence in our food system and surrounding environment. Bayer claims that glyphosate binds tightly to soil, degrades over time and does not bioaccumulate in the environment, food chains or our bodies. 

Despite these assurances, testing on samples from U.S. residents revealed that more than 80% of samples contained traces of glyphosate. 

Even more concerning is that nearly a third of the study’s tested samples came from children aged 6 to 18 years old. These results have led the Centers for Disease Control (CDC) to estimate that four out of every five Americans, aged six and older, have been recently exposed to glyphosate through their diet, skin contact or simply breathing in the particles.

Studies have repeatedly linked glyphosate to fatal diseases in humans. One such link: a research study in 2001 connected glyphosate to non-Hodgkin lymphoma. Since then, additional studies have also linked lymphoma to the chemical. 

Lymphoma is one of the most common cancers in the U.S across all ages. Last year, non-Hodgkin lymphoma was estimated to have claimed the lives of nearly 20,000 adults, teens and children in the country. 

These studies have led several other nations to restrict or phase out the chemical. Meanwhile, the International Agency for Research on Cancer (IARC) has classified the chemical as “probably carcinogenic to humans”. In June 2025, a long-term animal study also linked glyphosate exposure to a range of cancers, including leukemia and osteosarcoma, in rats. 

These findings only further supported the IARC conclusion on glyphosate carcinogenicity

The top U.S. manufacturer of glyphosate has spent billions of dollars to defend its safety 

A surge of lawsuits against the producers of Roundup has helped raise public awareness about the chemical’s potential health risks. Americans across the country have taken legal action because they believe that the well-known glyphosate-based herbicide has made them sick, and juries have been siding with them. 

Bayer, Roundup’s current manufacturer, has already spent at least $10 billion on settlements and jury awards from around 100,000 cases, and has set additional billions aside in anticipation of future litigation. 

At the same time, the company has actively lobbied state lawmakers to pass legislation that would block other cancer patients from bringing more lawsuits, while also filing a cert petition urging the Supreme Court to do the same. 

Bayer continues to defend the safety of glyphosate-based herbicides, yet it has reformulated the residential version of Roundup to remove glyphosate. Still, glyphosate remains the active ingredient in the industrial formulations used on our crops and farmlands. 

In defense of glyphosate’s safety, Bayer often cites industry-sponsored research, yet the company has not always been transparent about its influence on these studies. 

For instance, the company previously failed to disclose that it funded some of the studies. Documents disclosed as part of the Roundup lawsuits revealed that the company even sponsored ghostwriting of scientific and academic articles, interfered in the peer review process, and otherwise exerted pressure on both academia and the media.

Glyphosate use exposes us to unnecessary risks

While glyphosate-based herbicides may have once played a role in meeting agricultural demand, today our farmers grow more food than we consume. At the same time, sustainable practices, such as regenerative agriculture and pesticide-free farming, continue to grow in coverage, recognition and practice. 

These developments make clear that the potential risks posed by the use of glyphosate in agriculture are increasingly unnecessary.

We should not be heavily exposing our families, and our food, to chemicals until they are proven to be safe by rigorous, credible and unbiased scientific research. At the very least, we should be able to demand that the agencies in charge of protecting our health intervene when a possible health risk has been identified.

This is why we are calling on the Environmental Protection Agency (EPA), the federal agency responsible for regulating pesticides, to halt the use of glyphosate in agriculture until there is conclusive evidence that no link exists between this chemical and serious diseases such as cancer.

PIRG and our national network have a history of raising the alarm on routine exposure to toxic chemicals, including glyphosate. Now, we’re working to bring together the voices of farmers, small businesses and community groups who all want a safer and healthier future for our families.

The EPA must act now, before another 280 million pounds of glyphosate-based herbicides are sprayed across America again this year.

The president’s MAHA Commission acknowledged glyphosate-associated health risks, highlighting them in the “MAHA report” released in May 2025. The report also raised concerns about the influence of industry funding on pesticide research and the reliability of such findings. 

In addition to this, we urged the MAHA Commission to also recommend a moratorium on the use of glyphosate until, and unless, it is proven safe.

While the commission failed to include reducing the use of specific pesticides such as glyphosate in its August policy recommendations, we can still work to urge the EPA to get this potentially dangerous chemical out of our food, environment and communities. 

Read the original article on PIRG.org »

No, Your Cheerios aren't Filled With Harmful Pesticides

By Dr. Andrea Love
Published February 19, 2024 on ImmunoLogic

As usual, the Environmental Working Group (EWG) is using bad science to scare consumers. They and media outlets are trying to scare people away from demonstrably safe and nutritious conventional food products.

Headlines about harmful pesticides in conventional foods are lying to you in order to create fear.

It is wildly irresponsible of supposed “journalists” to continue to platform this long-standing coordinated campaign by the EWG to erode science literacy and harm public health.

Some background

The Environmental Working Group (EWG) is a pro-organic activist organization funded by large organic farms like Earthbound, Organic Valley, Stony Field Farms, and Applegate Farms to demonize conventional products and encourage consumers to buy their products instead. EWG brings in $13 million a year that funds their disinformation campaigns. This is the same group that creates the falsified “Dirty Dozen” list of conventional produce supposedly ‘contaminated’ (they’re not).

EWG routinely exaggerates risks to consumers, promotes products backed by their donors, and uses flawed methodology to make claims not backed by legitimate data. EWG issues product safety warnings that have no evidence to support them. They are in opposition to modern agriculture, biotechnology, and have even spread unfounded claims about vaccine safety.

EWG is notorious for spreading fear about chemicals and exploiting chemophobia, the appeal to nature fallacy, and low chemistry literacy. They problem is, through their lobbyist arm, their disinformation impacts health policy and our laws.

The accuracy of EWG reports and statements has been criticized by scientific experts. Its warnings have been labeled "alarmist," "scaremongering," and "misleading". Even though their claims are misleading, millions of people, even those making policy are influenced by disinformation they distribute.

While the EWG claims to help human health through research and by advocating for industry changes, in reality, they do the opposite.

EWG should never be utilized as an ‘expert source’ of information, even though they are routinely quoted by media outlets on topics related to chemicals and food.

Toxicologists and other scientific experts have detailed their flawed science and faulty research methodologies which they base their claims on.

• They routinely make claims that are in direct opposition to credible scientific and medical agencies, their methods are not supported by any legitimate scientific organization, and frequently cite studies that are not peer-reviewed.
• They exaggerate toxicological risks of chemicals, overstate potential impacts to human health, and take findings wildly out of context.
• Their methods routinely implement chemophobic messaging and appeal to nature fallacies and utilizes fear-based marketing to scare consumers away from products that are demonstrably safe.
• They frequently cherry-pick data that are favorable to their donor corporations, particularly claims related to unsubstantiated benefits of organic products and harms of gene technology, while simultaneously omitting more robust and relevant data.

The “science” EWG uses lacks credibility, but preys on emotions of consumers, leverages fear-based marketing, and coerces people into buying specific products.

Their newest fearmongering campaign? Oat-based cereals, supposedly because of harmful levels of chlormequat.

What’s worse? Media outlets are echoing this nonsense. Headlines like:

“Pesticide linked to reproductive issues found in Cheerios, Quaker Oats and other oat-based foods”

“Chemical That May Cause Infertility Found in Cheerios, Quaker Oats”

“80% of Americans test positive for infertility-linked chemical”

To be clear: these claims are not truthful. Media outlets are sharing clickbait that demonstrates they didn’t even look at the study or the data.

Their website (linking for visibility, but don’t give them any more traffic), shows their history of demonizing chlormequat. Loaded and false phrases like “highly toxic”, “highly problematic”, “disrupts fetal growth”, “damages the reproductive system”, are everywhere, paired with a photo of a baby. ALL of this is designed to target your emotions, and NONE of this is supported by data.

Chlormequat has been around since the 1950s and is approved for use globally. In the US, it is approved for ornamental plants as a plant growth retardant. It is primarily used in greenhouses and nurseries for geranium, poinsettia, begonia, African daisies, and hibiscus. Contrary to EWG claims, chlormequat is rapidly metabolized and degraded by plants, animals, bees, and soil microbes.

EWG wants everyone to believe that ANY chemical at ANY dose that isn’t ‘organically approved’ is TOXIC. They love using that word toxic, and they almost always use it without context.

With everything, the dose makes the poison.

Their war on chlormequat has continued with a recent self-funded ‘study’ from the EWG which they claim proves how widespread and harmful chlormequat is.

Their study, “A pilot study of chlormequat in food and urine from adults in the United States from 2017 to 2023” is now being circulated by nearly every media outlet. Yes, it is highly irresponsible of media outlets to continually use EWG as a “credible” source - they couldn’t be further from it.

Main claims the EWG makes:

• Detectable levels of chlormequat were in 92% of nonorganic oat-based foods purchased in May 2023.
• Chlormequat was present in 77 of 96 (80%) of urine samples taken from 2017 and 2023, with levels increasing in the most recent years.

Detection does not equal clinical relevance.

This is a common strategy used by people who spread fear about certain chemicals (ironically, not other chemicals). Everything is chemicals. You’re a sack of chemicals. The dose makes the poison with everything. EWG employees seem to have forgotten all of this. The EWG’s foundation of fear-mongering is based on wild exaggeration of ‘detectable’ chemicals. 

We have some of the most sensitive analytical chemistry tools on the planet. That means, we can “detect” levels of substances that are miniscule. 

A part per billion is equivalent to 50 drops of water in an Olympic-size swimming pool, or one second of time in approximately 31.7 years.

A part per trillion is equivalent to 1 drop of water in 20 Olympic-size swimming pools, or one second of time in approximately 31,700 years.

Think about how small those values are for a minute. This is the range we are talking about when we talk about ‘detectable levels’ or ‘residues’ of pesticides. These are TRACE levels. TRACE levels do not equal clinically-relevant levels. Detectable does not equal meaningful.

Ok, let’s look at the data now. They claim 92% of non-organic oat-based products contained chlormequat. How many samples did they look at? How many different products did they test?

Media outlets like CBS are using these data to say things like chlormquat is “showing up in the overwhelming majority of oat-based foods sold in the United States, including popular cereal brands Quaker Oats and Cheerios.” WRONG.

The overwhelming majority? They looked at 25 samples in TOTAL. Twenty-five. Most of them from 3 name brands.

25 conventional oat-based products, 8 organic oat-based products, and 9 conventional wheat-based products, most from 3 major name brands were used. This is egregious cherry-picking. Do you realize how many different products exist containing oat and wheat? 

As a good scientist, I looked at supplemental data to see what was actually tested.

Two Boxes each of:

• General Mills Cheerios (one in May 2023 and one in June 2022).
• General Mills Honey Nut Cheerios (one in May 2023 and one in June 2022).
• Kellogg's Special K Fruit & Yogurt one in May 2023 and one in June 2022).
• Quaker Oatmeal Squares Honey Nut (tone in May 2023 and one in June 2022).
• Quaker Old Fashioned Oats (one in May 2023 and one in June 2022).
• Quaker Instant Oatmeal Maple & Brown Sugar (one in May 2023 and one in August 2022).
• Quaker Oatmeal Squares Brown Sugar (one in May 2023 and one in August 2022).
• General Mills Cheerios Oat Crunch Oats n' Honey (one in May 2023 and one in August 2022).
• General Mills Frosted Cheerios (one in May 2023 and one in August 2022).
• Quaker Simply Granola Oats Honey & Almonds (one in May 2023 and one in August 2022).
• Quaker Chewy Dark Chocolate Chunk (one in May 2023 and one in August 2022).

One box each of:

• Walmart Great Value Oats & Honey Granola
• 365 Whole Foods Market Fruit & Nut Muesli
• Good & Gather French Vanilla Almond Granola
• 365 Whole Foods Market Organic Raisin Granola
• Quaker Instant Oatmeal Organic Maple & Brown Sugar
• Simple Truth Organic Instant Oatmeal Maple & Brown Sugar
• Simple Truth Organic Oats & Honey Granola Clusters
• 365 Whole Foods Market Organic Chocolate Chip Chewy Granola
• 365 Whole Foods Market Organic French Vanilla Granola
• 365 Whole Foods Market Organic Old Fashioned Rolled Oats
• Simple Truth Organic Toasted Oats Cereal
• Arnold Whole Grains Healthy Multi-Grain Bread
• Band of Bakers Harvest Loaf
• General Mills Cinnamon Toast Crunch
• Gold Medal Premium Quality All Natural Whole Wheat Flour for Baking, 5 lb.
• Great Value Half-Length Spaghetti
• Kellogg's Frosted Mini Wheats
• King Arthur Flour All-Purpose Unbleached Flour
• Nabisco Ritz Crackers
• Nature's Own 100% Whole Grain Bread

I need to emphasize that buying a single box of one specific product at one grocery story in Washington DC during one specific date does not constitute the OVERWHELMING majority of oat-based foods.

They tested singular boxes of a selected array of various brands of food products for chlormequat. Already sounds like a fishing expedition. Let’s go back to that data table.

Detected levels range from from ND, which means NOT detectable, to, at the very high end, 291 parts per billion. 291 parts per billion. Let’s visualize that.

291 parts per billion is 3 cups of water in an Olympic swimming pool (660,000 gallons). 291 parts per billion is equal to 4 minutes 51 seconds in 31.7 years.

Do either of these seem like a lot?

In a box of cereal weighing 14 ounces:

We’ll use the highest detected level of chlormequat for argument sake: 291 parts per billion, found in one box of Quaker Old Fashioned Oats in June 2022.

291 parts per billion. 291 parts per 1,000,000,000 parts. 291 g per 1,000,000,000 grams.

14 ounces is 396.893 grams. That means there was 0.0001155 grams of chlormequat in a 14-ounce box. That’s 0.1155 milligrams of chlormequat in an entire box.

That’s separate from the fact was one sample (of only 25), and the values measured ranged from undetectable. This is not how robust studies are conducted.

Let’s assume we happened to get that one box of Old-Fashioned Oats and we ate the entire thing because we love oatmeal. We ate 0.1155 milligrams of chlormequat. Do we need to be concerned like the EWG and clickbait media outlets would have us believe?

How much chlormequat poses a risk to us?

Remember, the dose makes the poison for all things.

There are 2 levels set for regulated chemicals like conventional pesticides: acute exposure level and chronic (daily) exposure level. Acute exposure refers to what one can be exposed to in a single setting and not experience adverse effects (since our excretory system can only do so much work at once), whereas chronic exposure limit assumes daily exposure over one’s life.

Based on the body of scientific data (epidemiological, animal, in vitro, and in silicodata) and likelihood of exposure, a no-observed-adverse-effect-level (NOAEL) is set. This is the value at which point no effect has been measured in ANY of the data related to that substance. Regulatory agencies set an even more conservative level to account for population-level variability in sensitivity to chemicals (e.g. young children, those with kidney issues whose excretory systems may be impaired). This is the population adjusted dose (PAD).

The NOAEL level for acute exposure is 100 milligram per kilogram body weight per day (mg/kg/day), and chronic exposure is 5 mg/kg/day.

The acute population adjusted dose (aPAD) for chlormequat is 1 mg/kg/day.

The chronic population adjusted dose (cPAD) for chlormequat is 0.05 mg/kg/day.

Both PAD values are 100 times lower than their respective NOAEL levels, meaning they are extremely conservative. But using the PAD levels:

An average adult weighing 70 kg (154 lbs.) would need to consume 70 milligrams of chlormequat to reach the aPAD, equal to 606 boxes of cereal containing 291 ppb chlormequat in a single sitting.

An average adult would have to consume 3.5 milligrams every single day for the rest of their life to reach the cPAD, equal to 30 boxes of cereal containing 291 ppb chlormequat.

So, do we really need to be concerned?

No. Trace levels of chlormequat in these products are not a concern to human health.

The EWG is doing what it always does: exploiting the fact that most people, even news outlets, won’t bother looking at the data, how weak the study was, and put those numbers into real-world context.

The EWG, and every major news outlet that has picked up this flawed study and reported on it without even looking at the methods or the data are contributing to spreading disinformation and exacerbating health anxiety.

The EWG is lying to you about what are real concerns and what aren’t when it comes to our food. This study doesn’t demonstrate any of the claims they are making, but their PR team and their figureheads have lines of contact to media outlets who foment fear with clickbait headlines and misrepresentation of reality. 

Note: Some text summarized. View full charts and commentary at the original article listed below.

Read the original article on immunologic.org »

Read more from the "In the Weeds" Series »