Lots of fresh horse manure's arriving at my place next week.
Conventional gardeners say you must rot horse manure for a year before using it. Is hugelkultur more relaxed about this by letting me build my mound with fresh manure right away? I don't have room to let it sit around doing nothing. My plan is to lay layers of twigs, leaves, logs, hay and finally with manure then plant seedlings on it.
Also, what should I do with my old clay soil? There's mountains of it because I've dug it out of the ground to make the bed deeper. Is it best to throw it out, or should I mix it in with the mound? I don't think it's good soil because it hardly has any worms in it and even weeds barely grow in it. I moved into my place just a few months ago so I don't know the history of the soil.
My understanding of Hugels is that they are entirely made up of rotted wood decomposing in the soil, but the hugels I have made have always included 50% sheep manure because I had plenty of it. Even seven years later they are thriving so I can't be making that much of a mistake. I have always planted right on top of fresh manure, but mine was sheep and I know sheep manure does not need to be aged; it does after all come in convenient pellet form!
My experience lines up with what you propose to do.
I just recently (May) built some hugels that included a good amount of freshish horse manure. I would recommend layering it into the mound and then mixing some as best you can with your clay soil to put on top. If you're just building it now I'm assuming you are just going to cover crop it for the winter? In that case I think it would be better than great, if you are planting food crops immediately into it I might worry a bit about contamination and nitrogen burn. Incorporated into the wood in the mound though I think is probably superior than a straight wooden mound.
One aspect of horse manure these days is the possibility of herbicide carryover, usually picloram, clopyralid, or aminopyralid, so research into what you are getting and testing the manure on sensitive plants before integrating it into the environment is called for.supposedly it can take years before the herbicides degrade.
I think you're fine adding it in there, though it may accelerate the breakdown of the wood.
When I get a new pile of horse doo, I let it sit for a few months then plant seeds in it. The persistent herbicides on hay are supposed to target broadleaf plants, so I plant various broadleaf plants to make sure they sprout and leaf out normally. So far this seems to have prevented any contamination.
Sorry I know this an old thread, but I figured I would add in my 2 pennies worth. Year before last I recieved a pickup bed overflowing with horse manure from a ranch down the road. I lightly spread it on the garden and piled the rest of it at the end of the garden. I had started most of my seeds in pots but a few either didn't sprout or died before I had the time to plant them in the garden. So I dumped the pots out on the horse manure. We had a butternut squash plant that decided to grow there. I saod what the heck and left him there. He gave out 47 squashes!!! He also used up the whole pile of manure. It was completely flat by the end of the season.... So bassd on my limited experience you should do fine with it but keep in mind the pesticides and herbicdes as mentioned above.
Yeah, I would test it out with a planting of broadleaf species right onto the mound in the manner mentioned earlier.
Other than that, I would keep in mind that if you are building a hugelbeet that is six feet or more in height, and it sounds like that's probable in your case, as you dug out the bases, you have a lot of soil depth. You can put your horse manure in the middle of your buried wood, and pile other soil and compost and whatever else you're adding, and still have at least two feet between where your seedlings are and where the bed will be making a hot compost. So what if it's hot? Just don't locate it too near seedling roots. By the time your mature plants dig down that far, it will have composted some and cooled down.
Also, the observation about the volunteer butternut squash is reminiscent of exactly what happened in my first hugelbeet in its first year. I topped the bed with a mixture of the topsoil excavated from the 3 foot by 18 foot by 3 foot deep trench I had dug, a compost pile of mostly coffee grounds, elm leaves and kitchen scraps accumulated over two years, and then companion planted a variety of vegetables and herbs together. I distinctly remember my curiosity about a curcurbit vine that was leafing out much larger and fuller than the cucumbers I had planted there; the butternut squash vine it turned out to be produced four dozen butternut squash at an average weight of a kilo (2.2 lbs) a piece, and the largest double that and longer than my forearm. And this out of a Toronto, Ontario backyard.
I would suggest that you select heavy-feeding crops that benefit from such rich soil. Squash will love it. Beets too. All you really need to do is find a few keystone veggie species in different garden layers and build guilds around them.
Finally, I would take the same approach with your clay soil as the manure, in that you probably want to seed the whole thing over with a variety of green manures, to see what thrives and what doesn't. It will give you a good idea of what's there. And if nothing grows at all, I would still take samples to a lab and find out why rather than throwing it all out. If it's contaminated with something, there are things that you can grow in some cases that will sequester the pollutant. Hemp, for instance, is known for its ability to extract and sequester heavy metals from contaminated soil. Fungi are being used in areas contaminated by radioactivity, namely Fukishima, to do the same thing with the radioactive heavy elements. These things can't be used afterwards, but it does make it possible to clean the soil and use it again, rather than "throwing it out," which is a very Western euphemism for contaminating someplace you care less about.
Practically speaking, if it's clean, you should just mix your soil in with everything else. A high clay content will mean better moisture retention, and if you get a dry season, with a raised hugelbeet and the potential for wind dessication, you will appreciate that.
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