Allelopathic Mustard

I've seen recommendations in several books and other places for using mustard as a soil builder and cover crop, but as I was looking for a source for seed I ran across several sources that indicated it was strongly allelopathic, and even exudes broad spectrum biocides (killing many soil microorganisms). That brought me up short, so I was wondering what others' experience has been using this plant for soil building. Has anyone used mustard and found it to be generally beneficial?

Here's a link to the site that talks about the biocidal properties of it: Mustard stuff They're mostly talking about how awesome their variety is for its high concentration of this stuff, but it sounds like it's applicable to other varieties as well.

Quoting from the page:

Bio-fumigation Potential- Ida Gold Mustard and Pacific Gold Mustard have very high levels of glucosinolates. The interest in glucosinolates, which are allelochemicals that occur throughout the Brassica family, has been generated because of the possibility of using plant tissues as a substitute for or supplement to synthetic chemical pest controls. Glucosinolate degradation produces biologically active products, the most significant of which (for potential biofumigation) are isothiocyanates, which behave as general biocides and have broad-spectrum activity on soil microorganisms. Some commercial soil fumigants use Methyl Isothiocyanate as the chief fumigant or as the active pesticidal agent produced from the degradation of other constituents.

I'd be interested in knowing if the same thing applies to Rapeseed. I'm planning on doing small areas of rapeseed next fall.
William

Brassicas are all in the Mustard family, I wonder if any of them have alleopathic qualities? Finding more and more alleopathic information out there than I ever knew existed..maybe we need a thread on the permies site listing things that have been known to be alleopathic all in one place?

Brenda Groth wrote:Brassicas are all in the Mustard family, I wonder if any of them have alleopathic qualities? Finding more and more alleopathic information out there than I ever knew existed..maybe we need a thread on the permies site listing things that have been known to be alleopathic all in one place?

From what I been able to find (not much), it sounds like most of them have at least some level of it. I haven't been able to find much in the way of quantitative info though, and I haven't noticed my garden brassicas interfering too much with the other stuff I have growing nearby (clover, herbs, flowers, etc). It's hard to find specifics about what it's supposed to be doing. The part that really surprised me was their claim that the mustard puts out a general biocide that kills various kinds of soil life. If that's true then I think I can live without mustard... but I don't know how strong the stuff actually is. Could be a case of a "hard sell" falling on the wrong ears.

I think the allelopathy thread is a great idea. That would be really helpful for setting up plant communities.

Sounds like permaculture for the paranoid. Let's find something else we can declare dangerous. I tend to
trust Mustard greens. I am not familiar with the varieties mentioned but still I just tend to trust them to be
o.k. Recently I have had horse manure and cottonseed meal and any other kind of meal taken away for
a variety of reasons. There is a thread of truth in a great many things that aren't truth.

Alex - that's a good point, but let me rephrase the original question to express a more balanced concern: If mustard is biocidal and allelopathic, I want to know that so that I can place it appropriately in my system. For example, it wouldn't make sense to add it to a vegetable garden polyculture with a bunch of other tender plants in the case of allelopathy, and it wouldn't make sense to add it to soil where I've carefully shepherded the soil life to a high level in the biocide case. However, if I want to outcompete some undersired species or encourage a crop destroying pest to move on, allelopathic biocidal mustard might be just the ticket. So I'd agree, it's not cause for paranoia or eliminating the plant from the repertoire, it's more about recognizing its best role in the greater system. To that end I still think it would be very good to know how much stock to put in the claims from that ad (both for that variety and for relatives).

It sounds like you have some experience with it in a permaculture setting -- have you found it to work well with garden polycultures?

Erik Lee wrote:Alex - that's a good point, but let me rephrase the original question to express a more balanced concern: If mustard is biocidal and allelopathic, I want to know that so that I can place it appropriately in my system. For example, it wouldn't make sense to add it to a vegetable garden polyculture with a bunch of other tender plants in the case of allelopathy, and it wouldn't make sense to add it to soil where I've carefully shepherded the soil life to a high level in the biocide case. However, if I want to outcompete some undersired species or encourage a crop destroying pest to move on, allelopathic biocidal mustard might be just the ticket. So I'd agree, it's not cause for paranoia or eliminating the plant from the repertoire, it's more about recognizing its best role in the greater system. To that end I still think it would be very good to know how much stock to put in the claims from that ad (both for that variety and for relatives).

It sounds like you have some experience with it in a permaculture setting -- have you found it to work well with garden polycultures?

My background in polycultures is modest and limited to small scale. Mustard greens are the standard fare of
southern gardens. Almost always grown in rows. It is boiled, so you have to pick quite a "mess of greens" to get
enough to eat once they cook down. Even in my intercropped beds they appear in short rows. I don't need a long
row because my wife and son don't really care for them. I have not noticed them being hurtful to other crops or
to the soil.Iif your inquiries lead to some definitive info that says that is the case I can make adjustments and grow
them along the fence by themselves and get them the heck out of the beds. It really would make sense to do that
anyway, it would make room for more variety.

she says tongue in cheek.....suppose I could plant mustard in my quack grass bed and see if it would kill off all the quack grass??? what a dream !

I'm no expert in this area but I will point out that all the sources/articles on mustard green allelopathic effects are on the germination of seeds. Apparently after a few weeks of decomposing the cut mustard greens, it's safe to start sowing seeds. But I wonder if it is safe to transplant seedlings into soil before that time or even while the mustard is still alive! I'm going to test this and report back

Erik Lee wrote:I've seen recommendations in several books and other places for using mustard as a soil builder and cover crop, but as I was looking for a source for seed I ran across several sources that indicated it was strongly allelopathic, and even exudes broad spectrum biocides (killing many soil microorganisms).  That brought me up short, so I was wondering what others' experience has been using this plant for soil building.  Has anyone used mustard and found it to be generally beneficial?

....

So, I've been trying to learn a bunch about cover crops and one of the ones I've been looking at is using daikon radishes as a cover crop to also break up the soil... but I stumbled across something on a vendor's website which led me searching and rather than starting a new thread, here I am reviving the ONLY relevant thread I saw that discussed glucosinolate...


On a page talking primarily about radishes, the site I was looking at said this:

Because radishes are part of the mustard family, radishes provide a modest benefit in terms of nematode and pest suppression. We suggest Yellow Mustard if you’re looking for more heavy-duty biofumigant action without the bio-drilling properties.

So 1) Apparently they claim radishes also have at least some version of this attribute (whether it is a benefit or a problem to work around) and 2) Mustard supposedly has a much stronger version of it.

I looked at their mustard page for more info and it says,

Incorporate plants into soil anytime before plants go to seed to prevent self-sowing. Wait at least 3 weeks before planting new crops.

So their tilling all of the biomass into the soil and even then after 3 weeks it seems all clear for new seeds.  

Who knows about trying to plant in the middle of it.  Or mowing and planting in the mulch.  I'm guessing it wouldn't have a great result though.


I also did a little bit more digging and found this study on the Google machine:  
https://www.sciencedirect.com/science/article/abs/pii/S0038071706001246

The concentration of glucosinolates (GSLs) and isothiocyanates (ITCs) was monitored in soil following the incorporation of pulverised high and low GSL varieties of rape (Brassica napus) and mustard (Brassica juncea) biofumigant crops. The concentration of both GSLs and ITCs in soil was highest immediately (30 min) after incorporation and they could be detected for up to 8 and 12 d, respectively. Irrigating with 18 mm of water over 3 h had no effect on either GSL or ITC concentrations.

And for whoever was/is wondering if the same would be true of rape:

The amounts detected were generally related to the amount of GSL added in the incorporated plant tissue. Maximum total GSL concentration detected in the soil was 13.8 and 22.8 nmol g−1 for rape and mustard, respectively, representing 7% and 13% of the original GSL present in the incorporated tissues.

So I THINK the lesson is mostly just don't cover crop with mustard and then till it into the soil... unless you just happen to actually want to kill off a bunch of the biology in your soil and are looking for a green way to do it. In that case, I think mustard is supposed to mature pretty fast lol.


I am definitely still curious if anyone else has any knowledge, thoughts, or experience to add to all of this though.

I am preoccupied with what it takes to grow fertility in place, rather than importing it.
I was searching for an edible,allopathic cover crop that affect seed germination, not transplants, found mustard and Google led me here!
I'm imagining mowing a field of greens to about an inch high, then transplanting directly into it.
I think you could even direct seed successfully, if you put down a layer of compost first.
I'm pretty certain the mustards would bounce back.
Weeding would become harvesting

There is a useful crossover between the needs of deer food plots and the possible use of mustard or diakon as a self seeding cover crop, making them easier to acquire.
I looked into horse radish as a perennial substitute, but it inhibits root growth as well as inhibiting germination.