Roundup and soil

overpaidmuniguy

overpaidmuniguy

Location
Cleveland, OH
Does anyone know if any research has been published on the effects on soil health from using Roundup or other glyphosate herbicides?

Just wondering if the stuff is as inocuous as it is generally assumed.

I'm usually suggesting mulch around folks trees, but establishing a low-maintenance bed takes more than just dumping mulch onto a lawn. I've found newspaper under mulch works great for new beds, but most folks in my town pay others to get their hands dirty, and so landscapers with Roundup would be the generally preferred method.

I suppose I'm a bit hesitant to suggest Roundup outright, not knowing its effects on soil organisms, am I just paranoid?

Thanks,
Ryan
 
hiah dude......unfortunatly its not so cut and dry when using roundup and other glyphosate products. Depends on how many times the person responsible applicates the area,how concentrated the dose was, even down to what nozzle was used.If the person who applicates sticks to the guidelines then there isnt a problem,Ive done so for years with no detrimentle effect to any trees what so ever. obviously if the trees in the bed have any open wounds then i wouldnt advise spraying the beds for awhile. hope that helps a bit.
 
We always suggest that people mulch heavily (>3") with coarse wood chips and top off with a nice looking double ground. The coarse wood chips allow you to mulch heavier than usual with no detrimental effect, while also suppressing weeds. The top dressing of double ground is for aesthetics. No Round-up is needed for this method.
 
A good weeding first,then a good preemergent.That is good as well.To do mulch well does take a little effort. even if you add 2" per year in five years thats 10" !! A good thing to do is every, or every other year break up and agitate the existing mulch and then top dress as limbwalker suggests. Make sure if using chips that they are composted at least a year . Raw chip can suck the Nitrogen out of the soil!! watch mulch creeping up to the trunk all kinds of root issues will develop ,Girdling and the like
 
I think that the idea that fresh chips "suck" the nitrogen out of the soil is unfounded. I was told this by several old arborists, but in my experience, there are no detrimental effects to using fresh chips.
 
I have wondered about Roundup myself. In fact, I ask every professional I meet what their preference and responses have been. So far, all have said "No ill effects" and they, collectively and individually, have used this product for years. But this is effect on the tree, not specifically on the soil. I would think, though, that if it negatively impacted the soil over time there would then be signs in the trees.

On the mulch... We use, and recommend, whole tree chips. We use them, most would say, excessively here at our place. The biggest issue is NOT to dig them into the soil but top dress and let them decompose and do their nutrient-cycling thing. They will gradually break down. Excellent for replenishing the soil on a slow and steady basis.

Sylvia
 
Hey I am about to prove this out one way or the other. I am presently working on a big project where a landscaper brought in fresh wood chips and placed them in the woods around a very large stand of Tulip poplars. There is about a 95% mortality rate for these trees and there have been no other disturbances. Also the die back line directly follows the wood chip line. I took soil samples yesterday . About 20 in the dead area. And the same in the wooded area next to it. When I talk to the pathologist I will let you know!!
Our state Dep says in there "proper" mulch brochure that raw chip is some of the worst mulch, and that 1 year composted is one of the best!! I have often wondered why ,when we use fresh chips for weed control it works so well?! It does not actually suck out nitrogen. It merely takes available N to break down the chip.Some people who make mulch actually have the carbon to nitrogen ratios lab tested to make sure they are in a proper balance. www.state.nj.us/dep/forestry/community
 
Here at my parents place, we had this area of the yard where 3 Beech trees, and a massive White Oak sat. This area was just overgrown grass. My old boss started dumping fresh chips here probably 12 years ago to keep the weeds down. So for 12 years straight there was a constant supply of green chips, usually 4-6" deep but not directly up to the trunk. Now that I have my own business this is also where the chips go. I can tell you the trees never looked so happy. The soil directly under this top layer of fresh mulch is amazing, and I do believe the tree's are thriving from it. It helps keep soil compaction down, as I am constantly driving the truck underneath to dump chips/wood.

From that experience alone, I cannot see how green mulch is going to kill a tree.

In the picture below, all inside the red line woodchip lay to rest.

http://i31.photobucket.com/albums/c351/Brendonv/woodchip.jpg
 
I talked to a water quality tester for new york a couple years ago. I asked if he was finding any MTBE (gas additive) in the water. He told me no, but he was finding glyphosphate. The story is it is supposed to break down into harmless compounds. Might just be a Monsanto story.
 
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I think that the idea that fresh chips "suck" the nitrogen out of the soil is unfounded. I was told this by several old arborists, but in my experience, there are no detrimental effects to using fresh chips.

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I agree KY.....
 
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a landscaper brought in fresh wood chips and placed them in the woods around a very large stand of Tulip poplars. There is about a 95% mortality rate for these trees and there have been no other disturbances.


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Did the landscaper drive any equipment in the critical root zone? I am interested to see how the soil samples bear out.
 
A friend of mine who is a plant pathologist professor at the U of MN told me that glyphos are quite safe to use according to label. Makes sense to me. He said that problems arise when agriculture usage goes on during rain and the glypho washes off into surface water. If it stays in the soil it will break down and change like Monsanto has said for years.

A research article in the Journal of Arb showed that only the very top soil layer had a drop in N with new mulch. In a very short time the N went back to normal because of the composting benefits of organic mulch.
 
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A friend of mine who is a plant pathologist professor at the U of MN told me that glyphos are quite safe to use according to label. Makes sense to me. He said that problems arise when agriculture usage goes on during rain and the glypho washes off into surface water. If it stays in the soil it will break down and change like Monsanto has said for years.

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David speculated this very scenario when we were talking about the above reference; i.e., that people many times are too casual about disposal or useage of glyphosates and other products like it.

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A research article in the Journal of Arb showed that only the very top soil layer had a drop in N with new mulch. In a very short time the N went back to normal because of the composting benefits of organic mulch.

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I was looking for that article to quote. This information is also in Harris' book on arboriculture. This is the reason that it is effective as weed control but not harmful to established woody growth unless dug into the soil. The only ill effects I, personally, have experienced was inadvertently using mugo pine chips that had white pine scale under my Scotch pine (which now has white pine scale). So definitely would watch for bugs and such. I would also go cautiously on using fresh wood chips that had a known pathogen such as armillaria or verticillium wilt (even though studies have shown little transmittal of these diseases, it is still possible).

I, too, will be interested in what the pathology results show. As with over 20 years of using whole tree chips as top dressing on soil under trees, in gardens with everything from shrubs, to perenials, annuals, vegetables we have not experienced an adverse reaction nor have we received a single call from someone who had a tree killed.

If any nondecomposed product is dug in or worked into the soil it will tie up nutrients and organisms during the decomposition process. During that time those nutrients will not be available to the plant.

Sylvia
 
I suppose I'm guilty of poor scientific method, i.e. looking for research which backs up my hunch. With published stuff on fertilizer and decreased microbial activity, and increased pest attraction, etc... I was suspecting that there might be a similar situation with Roundup, possibly leading to some detriment to soil life.

On mulching, I've recently been dissapointed with a number of trees I mulched this spring. (Some residents in the city where I work have found that not only were their trees pruned, but a mulch bed appeared where there was none when they had gone to work that morning... wood chip banditry) Wood chips definitely smother turf, but only where the layer is thick enough. I've seen a few looking pretty crummy, mostly with the turf re-emerging from around the trunk where the chips were thin. Welcome back weedwacker!

Nitrogen loss from green chips as others have pointed out is quantifiable, but I feel negligible (again, my hunch) compared to the benefits for long-term plant health. (my rationalization for laying down chips red-hot) Especially for a guy in my position, my options are mulch with what's in my chip box, or don't mulch at all.

Now that raises another idea, if you make mulch beds from the chips at the front corners of the chip box, has the quick release Nitrogen from that morning's coffee restored a more favorable C/N ratio?

Later on,
Ryan
 
Just to keep you all updated .I sent samples to the lab .The pathologist at the lab went into a lengthy diatribe about the ill effects of the Fresh chip method on certain species. When this thing is wrapped up i will follow up!
I never thought this was an issue prior to now. Maybe I will post some photos as well. All dead tulip poplars in the freshly chipped zone . Mortality follows the chip line exactly. No other cultural issues??!
 
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The pathologist at the lab went into a lengthy diatribe about the ill effects of the Fresh chip method on certain species.

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Yes, I would love to hear what he has to say. We all do understand that tree chips are not toxic waste, right? Most biotic disorders take awhile to establish to the point of killing a tree. Trees are pretty tough.

Abiotic on the other hand can affect a tree fairly rapidly. If you shut off its ability to uptake water, or suffocate its gas exchange abilities, response will be fast and dramatic.

Dave
 
Thick applications of fresh wood chip mulch can ferment (compost) in place. If you're really unlucky, the thermogenic phase of the fermentation can cause a pretty rapid rise in temperature. That's a big reason to not use fresh chips. Also, as has been mentioned, composted chips can have the communities of microbes doing there thing which would reduce the potential of adverse C:N ratios. The mortality described at the start of this thread does not sound like N deficiency, but could it be cooked tree?
 
Not to be a spoiler on the question of mulch and tree death, but about my question regarding Roundup and soil health:

Is anyone aware of any detriment to soil health and microbial life that may result from residual effect from Roundup? We push mulching on trees to promote soil quality for long-term health, but I was wondering if application of Roundup might affect some unintended targets.

If everyone sees no problem with the stuff, I have been wasting some serious time weeding around my trees at home...

Ryan.
 
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