I have some Siberian Elms, which I would prefer in a hugelkulture instead of as trees. However, it has allelopathic substances in it. If I added mushroom starter of some sort to the bed, would this neutralize the toxins?
Which mushrooms would work best? The beds will be built of mostly small diameter wood and twigs, since this is for a vegetable garden in a dry climate, and I don't want a huge mound. Manure will be added on top of the fresh wood, and the whole works will be covered with a few inches of soil, not more, because of an extremely rocky soil. Then the surface will be sheet mulched, to prevent erosion and to smother a lush growth of bindweed. Which mushrooms would work best in this environment, (either in the surface mulch or in the core.) I was thinking of oyster mushrooms.
Does anyone have direct experience with destroying allelopathic substances with fungi?
Should the starter be added to the wood core, or to the surface mulch?
If I added the mushrooms in the fall, could I plant in the spring?
Fungi will break down allelopathic substances. However, as the disclaimers go, "your mileage may vary" "past performance is not indicative of future results" and "offer available for a limited time only". Seriously though, your questions don't have exact answers, and a little experimentation on your part may be necessary to determine the optimal mushroom species, watering conditions, manure to mulch ratio, etc.
This paper seems to suggest that the presence of Siberian elm in mulch is not a problem and gets broken down in a reasonable (3 month) time period. Oyster mushroom is an excellent choice as it is one of the white rot fungi that are better at decomposing allelopathic substances. The method I recommend for applying a fungal inoculate is to get an immersion blender and make some mushroom gazpacho in a big pail. Sprinkle it liberally all over the top of everything you want to infect and water it in good. Continue to water it daily until you get a good soaking rain. In a couple of months, you should be able to dig into the mulch a couple of inches and see lots and lots of white hyphae. Once you see hyphae, it's well conditioned for planting.