Farmers have been spraying herbicides for a long time. In spite of that, for years organic gardeners were never really concerned about the straw being so contaminated with chemicals that it would effect our vegetable crops — possibly for years — if you used it as mulch.
Then herbicides that belong to a family of chemicals called pyridine that don’t break down readily came on the scene and things changed. All of sudden we have to be extremely careful of what manures, composts, and mulches we use.
An Important Note:
Make sure you know the difference in Straw and Hay so you won’t confuse the two.
See my post Hay or Straw – Which to use for Mulch.Be extremely careful with hay that is not organic. It is much more likely to have the long lasting chemicals of the pyridine family on it. (clopyralid, picloram, aninophyralid or aminocyclopyrachlor)You may want to review my post Compost – Mulch – Residual Herbicides – What you can do About Them in Your Garden
We will not belabor at this time all the bad things chemicals do to our soil and gardens but will concentrate on whether or not we — as organic gardeners — can safely use straw that has been sprayed with herbicides.
The Answer is – it depends on
- what herbicide/pesticide was sprayed and
- how long ago.
I have been buying large rolls of straw from the same farmer for over 30 years. Many persisting herbicides have come on the scene over the past decade. Thus, I always ask about what if any changes my farmer has made in spraying his wheat fields. He always says the same thing — “no change” —- but I ALWAYS ask and take nothing for granted.
(And by the way, just so you’ll know —- straw is the stalk after the wheat grain is cut.)
Straw that I use for mulch in my garden. This roll was cut the same year I used it.
Even though I’ve known these folks for many years and think a lot of them, it’s still up to me to do my homework and know what the results will be from what they spray. They’re totally into the chemical way and uninformed enough to think that these chemicals are harmless.
What my Farmer Uses
The wheat that my straw comes from is sprayed with nitrogen and an herbicide called Harmony in January. In February or March it is sprayed with another herbicide/pesticide called 2, 4-D. (They’ve been using 2,4-D on the wheat ever since I’ve been getting straw from them <almost 35 years> and possibly longer.) (2,4-D is short for 2,4-dichlorophenoxy acetic acid)
Before you gasp in dismay — read all the information first.
I’ll tell you some of the bad stuff first. (Don’t worry — there’s better news after this.)
2,4-D was first used about 1940.
- You’ll recall that 2, 4-D is one of the chemicals that was in Agent Orange. (2,4-D can be much more harmful when mixed with another herbicide.)
- It’s also what Monsanto’s genetically modified corn has in it — so that the corn itself will be immune to the 2,4-D spray. That means even more of 2,4-D in the environment.
- If 2,4-D drifts on the wind when sprayed — it can harm susceptible plants like beans, cotton, fruit trees, grapes, legumes, ornamental, peas, tomatoes and other vegetables that are miles away.
- Excessive amounts of 2,4-D in the soil may temporarily inhibit seed germination and all plant growth.
- There are other warnings that come with 2,4-D about not feeding treated forage, fodder, soybeans, or hay to livestock. And the company warns that hay or forage should not even be cut within 30 days of its application. Also farmers are warned not to graze their cattle on crops that were sprayed for at least 7 days. Some sources say 14 days. (The same warnings are given for the herbicide Harmony.)
In spite of the Dangers of 2,4-D
There are over 1000 products with this pesticide/herbicide sold in the United States. It is one of top 3 largest selling pesticides in North America.
The active ingredient in Weed B Gone that many homeowners use is 2,4-D. I wonder how many folks spray their dandelions (or maybe their neighbor sprays) in the spring and then wonder why their vegetable seedlings are not doing too well. (Or maybe why they’re not feeling too well themselves?)
Here’s the information (the better news) that makes it possible for us to use straw sprayed with Harmony and/or 2, 4-D:
How long Pesticides/Herbicides take to break down — is known as their Half-Life.
Pesticides/herbicides break down through microbial and chemical deterioration.
The time it takes them to breakdown is expressed as Pesticide/Herbicide Half-Life.
The half-life listed for each (in various available charts ) is time required to breakdown under ideal conditions. Persistence of herbicides and pesticides will vary according to different factors including light, temperature, soil moisture, type, ph, etc.
There are 3 categories of Pesticide/Herbicide Half-Life:
- Nonpersistent – half-life of less than 30 days.
- Moderate – half-life of 30 to 100 days
- Persistent (like those in the pyridine family of chemicals) – half life of more than 100 days.
2,4-D Half-Life
Some sources indicate that 2,4-D has a half-life of 7 to 14 days. I’m no scientist but I figure since there are warnings to the farmers on the instructions that hay or forage should not be cut until at least 30 days after application — 30 days (or even a bit more to be on the safe side) would be a more accurate half-life.
Harmony
The half-life I found listed for Harmony was 12 days.
Figuring Safety using my Straw as an Example
Since the wheat crop that my straw comes from was sprayed in January and February, the 2,4-D and Harmony (using the Half-Life of 30 days) have already broken down by the time the straw is cut is cut in early summer.
GardenDmpls, a reader who seems to understand all this better than I do – left a comment to this post that was worth moving into the post. Here’s what she said:
“If they say half life is 7-14 days,but don’t touch until thirty days, that doesn’t mean the half life is around thirty days. Half life is the time it takes for half to break down. If the half life is 7 days, for example, if the original amount was 10 ounces, after one week there would be 5 ounces, a week later 2.5 ounces, after a third week, 1.25 ounces and a fourth week .625 ounces. What is important is when the amount left will be so negligible that you can ignore it.”
Usually by the time I use my straw it’s a year old — sometimes more. But I have used rolls that have just been cut and have never had a problem. And as I said — I’ve been using the straw for almost 35 years. (Back then — I knew nothing of residual herbicides.)
These 3 large rolls of straw are more than a year old.
Closing Thoughts
In spite of the fact that man seems to be doing everything he can to destroy the earth, he’s not quite there yet. Nature is powerful and does lots to help us in our quest to obtain the very best things for our garden so that it can in turn help us be as healthy as possible.
True, it’s not as easy as it use to be. We can take nothing for granted. We have to do our homework and search out what is safe and what is not. We must ask questions, get answers, and then know the facts.
If the straw you find has been sprayed with something other than the two chemicals mentioned here, I’ll give you a few sources at the end of this post to make it easier to start your research.
Bottom Line:
If your straw like mine — has been sprayed with Harmony and/or 2,4-D — I feel you can use it safely in your organic garden after the right amount of time has passed and nature has broken down the chemicals.
I’ve loaded my wheelbarrow and am ready to take this load to the garden.
Other Related Posts:
Compost, Mulch, Residual Herbicides – What you Can do About Them in Your Garden
Residual Herbicides in Composts – Part 1
Hay or Straw – Which to use for Mulch
Municipal Compost – Manures – Should You Use Them
A Few Starting Points for Research:
http://www.pesticides.montana.edu/Reference/minimizingpesticidecontaminatedsoil.pdf This is a good one. Easy to understand and it gives some good tables with information.
http://extension.psu.edu/cover-crops/news/2012/herbicides-and-fall-cover-crop-establishment Gives a chart of half life for various herbicides.
http://www.ces.ncsu.edu/fletcher/programs/ncorganic/special-pubs/herbicide_carryover.pdf
http://www.southernstates.com/articles/herbicide-residues.aspx
Check this one out. Another good starting point. Very general.
http://www.pbigordon.com/pdfs/LV400-SL.pdf
Specimen label directions etc. of 2,4-D weed killer.
________
Organic Gardening is easy, effective, efficient — and it’s a lot healthier.
________
All content including photos is copyright by TendingMyGarden.com. All Rights Reserved.
