Walnut Trees and Soil Toxicity
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- Jojo
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- Treeman
- Jojo
- Treeman
- Jojo
- Jojo
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- Darkwing
- Treeman
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» Jojo - Question from a reader...
I got this question by e-mail today.In January of this year we cut down a black walnut tree in our back yard. Could someone tell me how long it takes for the soil to improve in order to plant a garden or juglone sensitive plants.
That's a very good question. I have a few ideas on this, and I hope anyone who has experience dealing with this issue will drop a line here, or send me an e-mail so I can post all the findings.
I have heard it can take as long as it takes for the roots to decay. Decaying roots still relase juglone, so toxicity can persist for some years after a tree is removed. I would remove as many of the surface roots before undertaking major plantings so there are less roots decaying in your soil.
On the up-side, decaying roots will release less and less juglone as time goes by.
I've heard 3 years and 5. It could be more, it could be less. Much would have to do with the structure of your soil, how fast the roots decay, and what the roots on your tree were like. A longer season, as found in the south, would cause roots to rot faster.
Tomatoes and their relatives are a good indicator plant for juglone. These include petunias and flowering tobacco (Nicotiana). Plant them around the area. By doing this, you will be able to locate zones where there is more or less juglone present in the soil. These plants will turn yellow and die in a few weeks if the toxicity is high. If it is low, the plants may fail to bloom, or at least fail to thrive. In juglone-free soil, the plants will do well (of couse, with sun and requisite waterings).
The only problem with this test is that shrubs and trees and many perennials are much deeper-rooted than petunias and tomatoes. So if you plant a deep-rooted specimen in the same spot it may come into contact with decaying roots of juglone zones the small annuals wouldn't ever touch.
I have two other peices of advice for you, gleaned from a test on removing toxins of any kind from forage crop soils. First, if the drainage is good, water alot. The more you water, the more toxins will leach out of the soil.
Also, try buying a bag of gypsum (available at most agricultural and gardening stores) and sprinkling it over the soil. This can help break apart clods of earth down low and increase the ability of soils to leach toxins out, by changing it's atomic structure. You can't see what it does with the naked eye, but I have seen it work in many cirucumstances where agricultural toxins and high salts are a problem.
I hope this helps!
-- posted by Jojo
» Jojo - Another note...
By the way, most of the juglone under a black walnut tree is released by the leaves, nuts and hulls. Once the source of all that is gone, you will find the toxicity is greatly reduced.Juglone breaks down well in healthy soil with lots of micro-organisms. Keep the organic matter content of your soil high, and refrain from using chemical fertilizers and pesticides, which can hinder these soil fauna.
-- posted by Jojo
» Treeman - More on juglone residuals
JoJo,I have heard much of the same info you report. Your reader may want to consider using activated charcoal in the location. This is used to bind up mistakenly applied herbicides and may also have the effect of chemically binding to the juglone and therefore preventing its action on plants.
-- posted by Treeman
» Jojo - I used activated charcoal a few years ago -- on a skin infection
I used activated charcoal a few years ago -- on a skin infection that is. It worked very well.I've heard vaguely of the use of activated charcoal in agriculture, but upon looking it up, found lots of information on colon cleansing, and This page explaining a bit about what it is and how it's made in the Phillipenes. There's also this page about poisoning, which states that 1 gram of activated charcoal has a surface area of approximately 1000 square metres. Is it the same stuff?
Please elaborate if you will Treetoad. I'd be very interested to learn of possible applications it could have in this and other types of soil toxicity.
-- posted by Jojo
» Treeman - The Same Stuff
Yep this is the same stuff. The huge effectice surface area provides maximum chemical binding sites for such purposes. The msds sheet doesn't list any terribly serious toxic or carcinogenic effects for this material. I would suggest you vist the "charcoal home page at www.rpi.edu/~levinb/charcoal.html where there is a list of 130 charcoal info sites including a few regarding its use for neutralizing pesticides. A good article on this can be found at www.bae.ncsu.edu/bae/programs/extension/publicat/wqwm/ag442.html. Another article at hammock.ifas.ufl.edu/txt/fairs/31585. These should be a good start for further investigation.-- posted by Treeman
» Jojo - Hi Treetoad
Hi TreetoadThese sites could be of especial interest to those with soil toxicity problems, whether they are juglone related or not. I know a gardener who has an unknown soil problem, and we are undergoing tests to see if we can identify the toxin. It resulted from some very bad fill he bought a few years ago, to form a new bed and top up some of his existing one. He's learnt so much about gardening since making the mistake of buying this stuff. I am trying to help him in any way I can so if we find he has a specific toxin, we'll see if it's listed and maybe try out some charcoal.
Thanks for your info Treetoad! It's highly appreciated.
-- posted by Jojo
» Jojo - received by e-mail
This question was received today by e-mail...Hi,
I have a walnut tree in my yard, and when the walnuts fall on the ground I pick a few and cut the outer layer off, but the walnuts never seem
ripe. How do you ripen walnuts?. Maybe the squirrels are cutting them off the tree before they are ripe. Can you give me any answers?
Thanks
HI THERE
I beleive it is too early in the year for walnuts to be ripening, although this depends on where you are in the world. I found the bulk of mine were ready in October.
You may either be experiencing crows or squirrels or some such knocking them down, or the tree doing some natural pruning of it's own. Trees will often shed some fruit if they have too much to fully develop.
The hull of the walnut should turn a bit brown when they are ripe, and they will drop to the ground in great numbers. Gather them up daily so you get your fair share of them. If you let them sit the squirrels will steal them. I also recommend letting them sit for one month to sweeten up before eating.
I hope this helps - Jojo
-- posted by Jojo
» Treeman - Too early now and more
Yes, too early now. These aborts probably have real thin hulls and are quite light in weight.Later in September and October when they fall, you will first want to dehull them. Several ways of doing this- spread them out in drive way and let car wheels do the job. Dill a 1 3/4 to 2 inch hole in a stout oak board and wham them through with a hammer, or use an old (Antique)corn sheller I'm sure others have also developed godd dehulling methods. Then, like Jojo says, let them age or dry for a month or two before cracking.
-- posted by Treeman
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