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Are you worried about glyphosate lingering in your garden soil? Maybe you recently purchased a home and are concerned about the soil history. Or maybe you are moving from conventional to organic and are worried about your past use of round up. This gardening in Canada article is going to look at glyphosate and garden soil.
If you are new to this blog my name is Ashley and I am a soil scientist. I am located in a Canadian Zone 3 and a USDA Zone 4. I write articles, make YouTube videos, Instagram & Facebook posts all designed for Canadians and Cold Climate gardeners using science-based methods. If you are looking for anything specific be sure to let me know in the comments down below.
Glyphosate is round up. Round up as a product that is typically used as a broad leaf herbicide. It is meant for killing plants that are not genetically modified to withstand glyphosate being used. But the question becomes how long does it survive in our soil.
The first place I looked was scientific literature and the journal entry I thought spoke the most relevant to gardeners was done by the university of Cambridge. This study took glyphosate and looked at its effects on soil microbiology. It’s jorkin to consideration the depth in which the pesticide penetrated and the potential application strength.
Soil Type & Glyphosate
A common theme among all the journals I read was soil type. And this makes sense to me because the bulk density of our soil will determine how deep the pesticide penetrates. If you have a clay soil it is likely that the pesticide will not penetrate as name into the soil profile. This means the effects of something such as glyphosate being added to the soil will take less time to dissipate.
However if you have a sandy soil type the glyphoseate is more likely to penetrate deeper. This means it can potentially move into an area that is not as inhabited by microbes. Therefore it may take a longer period of time for the pesticide to break down.
How Does Glyphosate Disappear From Garden Soil?
So the first question we need to ask is how does glyphosate disappear from Our soil profile. And this is actually a concept we know very well. If you’re not familiar with agriculture and agri Foods Canada let me give you a run down when it comes to pesticides.
Before any pesticide can be approved for using Canada it needs to go through a review. During this review the process of elimination needs to be determined. If there is no clear path that allows for that pesticide to disappear within a certain period of time then it is not approved.
In a case of glyph we know what it’s made from. The main components include things such as hydrogens, oxygens, carbons, phosphorus and nitrogen. If you pay attention in our 17 essential nutrients video series you already know that all five of those elements are macro nutrients for plants.
Do Microbes Eat Glyphosate
This means there are going to be microbes specifically designed to decompose elements that have these nutrients. This decomposition process will take place at the moment I’m going to say it interacts with the soil surface. Studies are mimicking this for us in extraordinary ways.
After glyphosate is applied there is an explosion of microbial activity. The way we do this is through measuring the carbon and nitrogen mineralization within the soil. There is a notable increase in mineralization rates at the time of glyphosate introduction. This increased mineralization rate continued onward for approximately 14 days.
It’s important to know that during the studies the mineralization rate went up but the microbial biomass did not. What I mean by that is that microbes didn’t multiply at an exponential rate adding to the microbial count. This is done despite the fact that there is an influx of carbon nitrogen mineralization.
The bacteria found to the the predominant decomposer of glyphosate are two isolates. Pseudomonas sp. and Bacillus sp. You can make this at home see the below video or this article.
Things To Consider
One thing not noted in the Cambridge study but is my personal opinion is the potential idea that this balanced microbe biomass may be an indicator of the harms in glyphosate. For example when we use things such as molasses to encourage microbes within a compost pile we generally see an increase in the microbe biomass. This means the excess food is resulting in a population boom.
However in the case of glyphosate we are not seeing the boom only the mineralization. Could this mean that the access food available is toxic. Meaning they are consuming and reproducing but only a certain amount of offspring are surviving. This is keeping the entire population balance despite the popular influx.
Again I cannot stress enough that that is my personal opinion and not what cited in the study. This means there’s zero literature to back up in my claim.
How Deep Does Glyphosate Move Into Garden Soil?
There are three factors that affect how deeply glyphosate will penetrate into your garden soil. The first one being soil type which we mentioned above. The next two are going to be dosage meeting the volume of liquid you applied. And the third being the distance in which you sprayed.
If you are leaving a liquid on the soil surface in a pooling fashion it is going to penetrate deeper into the soil profile. If you spray from a recommended distance less pesticide or penetrate into the soil surface. This is important because the deeper the pesticide penetrates the more likely it is to stay around for a longer period of time.
With anything that involves chemicals you want to ensure you are dosing according to the packaging. This means the volume of pesticide used should be the recommended amount on the package. The distance in which you spray should also be the distance that is indicated on the package.
Does Glyphosate Affect Mycorrhizae?
Glyphosate does affect Mycorrhiza fungi. The effect is negative when it comes to cultivable fungi. Ultimate result is changes in the molecular structure of soil fungal communities after application. This means overall fungal communities are negatively impacted by the use of glyphosate.
Glyphosate Affect In Algea
Algea and glyphosate also do not mix. A healthy soil is noted to have 5% volume Algea. However when glyphosate is added the algae tends to disappear. This means ultimately that that soil is missing a much-needed microbial component.
It’s important to note that currently, despite the fact that we know algae is important in a soil system, scientists do not include algae as a major part of soil studies. It is currently a microbe that is pretty much ignored when it comes to looking at the effects certain products have on the soil ecosystem.
How Long Does Round Up Stay In Your Garden?
This again depends on how deep the roundup has penetrated. But if you were using the proper techniques listed on the packaging it only stays for approximately 30 days. This does not mean it is as potent on day 30 as it is on day one.
The first 24 to 48 hours is the most toxic time for the round up product. After being exposed to the soil it begins to degrade. This means it slowly gets broken down into its original components. This means that by day 30 there’s next to no signs of glyphosate being used in the system.
If it has been liberally applied and made it past the first 5 mm or so of soil there may be a longer wait time. Most of the studies I looked at gave a maximum time frame of 50 days. This again means that by day 55 glyphosate may still be present but the potency is greatly reduced.
You now officially understand what it takes to get rid of glyphosate in a garden soil. Between natural microbial processes and time it is likely the pesticide will not exist after the first month. This means it is safe to eat any fruits or vegetables that have been grown in the presence of glyphosate. this also means if you’ve recently purchased a house or your neighbours used round up in the area you are safe.