I have got the book "Sepp Holzer's" Permakultur, which is only available in German. He writes that if you make a hugelbeet with crushed material, then you should not plant peas and beans etc in the first year, because there would be too nutritious, spinach i.e. might even accumulate to much nitrate. But when you make your bed with coarse material, i.e. whole logs then you can do this. For me that is not very clear, there is a long way to go between a log and woodchips, and even then I cannot see that they rot that quickly to give you too much fertilizer. What do you think? If what Holzer says holds true you should not plant spinach or lettuce in a heavily composted bed either.
I think Sepp knows what works for him under the conditions on his farm. Not sure that the explanation is 100% correct in this case.
If shredded wood is added to the soil, the biggest danger in the first few years is nitrogen deficiency, not nitrogen surplus. Wood is rich in carbon and low in nitrogen, and the fungi and bacteria will out-compete plants to absorb any nitrogen in the soil as they feast on the wood. This is less of a problem if the logs are whole (the surface area is much smaller, breaks down more gradually). Shredded or crushed wood might raise the potassium level in the first years, but it would take a lot of wood to cause a potassium toxicity problem I think.
my understanding has been that when wood chip is dug into the soil there is nitrogen up take if added on top around plants not so, also that tree trunk/branches material is mostly a carbon source with little other nutrients, the best nutrient source is green type mulches, ie.,. spoilt hay etc.,.
now with this hugelkultur (hill culture), it is away of getting rid of large tree material, the logs of course are going to take a very long time to break down, so realy can't see that sort of set up causing too much problems for planting crops.
for me if i had that sort of material i would possibly use this system but i certainly wouldn't be going out looking for mateial just to use the system. i've found most gardeners want to build a garden and start planting in short order. this is where what we do counts. in our beds yes i would lay tree material in the bottom. i see more value in splitting logs and laying them in the bottom of a bale garden.
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From what I can tell Sepp has a lot of empirical data, and some ideas that he has really work and really do wonderful things, but he hasn't figured out a workable theory for most of it. If you are a philosophical prgamatist you might want to follow him very closely, but that explanation makes no sense from a theory point of view.
We did some research on Hugelkulture (I thought hugel meant heaven not hill and my X is Austrian) and what we found was that the bottom layer was supposed to be rotten logs that were already decomposing. Covered that with brush, raw manure, rotten hay, topsoil, and compost. Original we had a dozer dig two areas 25' x 90' x 24" deep. We now have one filled pretty close to ground level, and eventually we want to get that 12" inches above grade. In that area this year we grew sugar beets, parsnips, potatoes, beans (masai), leeks, calendula, radishes, raddichio, okra, celeriac, fennel, and onions. Everything grew very very well. It seems if you can get wood that has begun to decompose you can begin growing right away.
Yea, that's the point and he also says you should plant right away, when beds are done.
To much fertility made me think when i started gardening. I have always avoided manure and doing very fertile beds. Of course i'm a bit lucky to have humus rich clayish soil and can grow in it without problems, just putting down hay, wait a bit and beds are ready.
What he says makes sense, but i think you've misread a bit. I can not quote from book or anything, so i'm telling you with my own words, not mine, but his understanding.
Nutrient aviability to plants depends on break down of the material inside the bed. Crushed material breaks down faster, so most nutrients are available faster. He says it happens the next year after doing the bed with crushed material. "Of course this totality depends on your climate etc." Anyway, when there is most nutrient aviability he suggest to plant pumpkins, cucumbers, cabbage, tomatoes, corn, potatoes, ... You should plant peas, strawberries, beans only after four years when there is less nutrients. Plants that are feed to much are not so aromatic. Spinach can build up nitrate, and that's not good for our health.
Beds out of coarse material, whole logs. There is no high nutrient aviability the first year after making the bed, but then they release nutrients for many years.
What he had available for making the beds was spruce. He also told somewhere you should not cut down spruce logs or anything, more resin is extracted and you can have ph problems.