Cleaning soil after removing toxic plants

11 years ago

We are in the planning stages for creating a garden and chicken run in our back yard and I think I'm FINALLY going to get my way and get rid of the oleander. Since it's toxic to humans and chickens, I want to rip it out and plant a fruit tree there for shade (and fruit, of course!) instead, but I'm assuming the soil will still contain toxins from the oleander that has been there at least a decade or three.

So, how best to clean up the soil there so the fruit from the tree and the chickens will be safe? Should I plant a cover crop (if so, what?) for a season or two before putting in a new fruit tree? Just add compost and leave it empty for awhile (how long?)?

I've done a little reading and found the term phytoremediation, but everything I've found on the topic refers to chemicals in the soil from pesticides, heavy metals, etc. not plant toxins. (In fact, one site listed oleander as a great way to remediate toxic soil.... but that wasn't in reference to vegetable gardening.)

Another site said sunflowers are good for removing heavy metals from the soil, but how are they at removing plant toxins? I'd harvest and toss whatever cover crop I grow, but I'm wondering which plant(s) would work best and how long I have to wait.

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Comments (7)

User
11 years ago
You are assuming a level of toxicity for oleanders that only exists in bad TV shows. I have two tomato plants growing right next to the oleander hedge, and no one has dropped dead yet from eating the tomatoes.

Oleander toxins are "glycosides", they are readily decomposed by almost any fungus, mold, or bacteria. Shredded oleander branches degrade quite nicely in a compost heap just like all the other plant matter. Just don't eat the compost while it's fresh.

Cut it down, shred the branches for compost, dig out the roots down a foot or so with whatever works. After 30 years, backhoes and high explosives may be necessary. At the very least, a mattock or pick-axe will be needed.

The roots will decay where they are, and the fruits and veggies and chickens will do just fine.
Tiffany, purpleinopp Z8b Opp, AL
11 years ago
Oleander is poisonous to humans if ingested because of the cardiac glycoside in it. Never read anything about allelopathy from Oleander, and it is not a known juglone producer in any literature I've ever read.

http://www.employees.csbsju.edu/SSAUPE/biol106/lectures/poison.htm
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I'll take a look for other mushroom types that might work. A question related: I was wrong and the big tree we took down wasn't a birch, but an aspen. No big deal but rather duff wood - although I'll still split it and burn it eventually (only pleasure fires outside from time to time). I like splitting wood and it's decent exercise. Anyway, the question: aspen has bark that gets soft and starts to rot almost immediately, so in splitting and stacking, I basically have to cut off the bark, which is already damp, stringy and often sort of disintegrating in the hand. Thoughts on composting this? Just toss it in my big pile? Ir's a cold composting operation and gets emptied out every year or two (two more likely). Spread around? Put in a different pile somewhere else and just see what happens? Important to add a lot of extra water or some additional nitrogen (guessing that N can't hurt)? I'm lazy enough (apart from splitting wood) that I don't want to do anything extreme, but it'll have to get picked up and moved somewhere. There are other piles of mixed woodchips/leaves, but thinking someone else must have experience with something like this.
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gardengal48 (PNW Z8/9)
11 years ago
and it is not a known juglone producer in any literature I've ever read.

Oleander CAN'T produce juglone, since that's a hormone only exuded by the Juglandaceae, the walnut family and its related species. Allelopathy is an ongoing field of study and many plants produce allelopathic chemicals but few in concentrations serious enough to warrant attention, like the walnut.

Removing the oleander and as much of the stump as possible - same as you would do for any large shrub - is sufficient to assure safety of the soil for edible crops and your livestock.

FWIW, I have never read any evidence that so-called "toxic" substances -like the oleandrin glycosides - can be translocated or drawn up from the soil into other, non-specific plant tissue. Even heavy metals are typically not absorbed by plants in any significant or possibly harmful concentrations.
Tiffany, purpleinopp Z8b Opp, AL
11 years ago
Thank you for the clarification and expansion, gardengal.
jolj
11 years ago
Charcoal has been used to remove toxic from the soil.
As I understand it char works like bio-char, only it takes up toxic. Never heard of using it on Oleandrin.
Tomato plants are toxic, more so in new/young growth.
Many of the plant around you will Kill you, when ingested.
I think that you do not need to worry about the soil.
I agree with other posters.
I worked with a Landscaper when I was in school. At 10 year old I drug large oleandrin limbs & trunks to the curb & have never felt better the next day. I was taught from a very young age NOT to PUT any thing in my MOUTH, unless I knew what it was.
jeff_12422
Original Author
11 years ago
Ah, so those who told me to worry about it without giving me more specific instructions have been watching some bad TV, eh? ;-)

So glad to see a consensus on this - I got warnings from a few different people that I had to be very careful, etc. And then on the chicken forum I googled, there were very mixed opinions about whether the chickens would even bother to eat a toxic plant or if they somehow know better. (My dog isn't too bright, and he seems to know to leave it alone, but I have no idea how much dumber than a chicken he is, or isn't...)

Thanks for the feedback! Now to decide on citrus v pomegranate.....
toxcrusadr
11 years ago
Animals are amazing that way. Humans have pretty much lost touch with that genetic knowledge of plants.

Cleaning soil after removing toxic plants

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Tiffany, purpleinopp Z8b Opp, AL

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Cleaning soil after removing toxic plants

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Tiffany, purpleinopp Z8b Opp, AL

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