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I have had good luck in the past burying logs to create a Hügelkultur for my garden. This year I decided to build some raised beds and lined the bottom of the beds with logs to get the advantages of Hügelkultur and also to reduce the amount of top soil I had to haul to my back yard.

Unfortunately, I wasn't thinking and accidentally put in some black walnut logs. Now I'm worried I won't be able to grow anything because of the juglone chemical in black walnuts.

The logs were very broken down and nearly falling apart. They had been laying on the ground for what appears to be 5-10 years. I know the juglone probably won't be completely gone, but will it have broken down enough to not kill my veggies? Or should I spend 6 hours, dig it all back up, and get rid of the logs now?

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    I would suspect there is little poison left in the wood after weathering. When I had a black walnut tree ,the fallen leaves did not seem to make a big difference to weeds. Commented Apr 20, 2020 at 19:30
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    Leave the logs where they are. Any Juglone in the logs should have leached out long ago.
    – Jurp
    Commented Apr 20, 2020 at 21:46
  • Thanks for the replies. Think I'm going to try it this year and see how it goes. I can always dig it up in the fall if I have to. Commented Apr 21, 2020 at 3:33

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The logs were very broken down and nearly falling apart.

Then they're subject to decomposition, leave them alone!

From the science,

Degradation of juglone in water is pH dependent, it is strongly enhanced in alkaline conditions relative to lower pH in neutral or acid conditions. It degraded much faster at pH 9 (half-life 18 h) than pH 4.0 – 6.8 (half-life 60 days).

So after oxygen and water hits it, and it oxydizes you have a 60 day half-life. And 5 years (your conservative estimate) is,

5 years * 365 / 60 days = 30 half-lifes.

All of this is going to be obscured if the jugalone is locked in the walnut and it's working to preserve the veins, but I can't find any research on this.

Or should I spend 6 hours, dig it all back up, and get rid of the logs now?

Would that be better? Sure. Is it worth it, absolutely not. Not if you're the most bored person on the planet.

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  • Your advice was spot on. I have had zero issues growing veggies in the beds. Commented Jan 10, 2023 at 20:15

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