I've never heard of disease or bad bacteria being an issue. The issue, I believe is plant-usable nitrogen. When you put uncomposted material into a soil bed, bacteria multiplies rapidly as it feasts on the material. Those bacteria need nitrogen to multiply, and they take that nitrogen out of plant-usable nitrogen in the soil. The nitrogen is "tied up" in the bacteria. It's not gone. Just unavailable to plants, because plants don't eat bacteria. When the organic degradation is finished, many months later, the bacteria die, and those nitrates return to the soil.

If you have some reason to believe that nitrogen content isn't an issue, then I guess it's OK. Certainly if you seed the area with some high nitrogen fertilizer -- ammonium nitrate or urea, for example, you're probably good to go, though you might be careful about heat released by very rapid organic degradation. I always thought lasagna gardening was supposed to be basically in situ composting. That is, you dig in organics in the bed, and just wait for decomposition there to finish. With hugelcultur, your organic is wood, and that decomposes slowly, so it may not eat as much nitrogen.

It's difficult to get enough organic matter into southern gardens. Soil bacteria never slows down in warm regions and can consume some two tons of vegetable residue per acre each year. Soil is not just degraded rock. An nrcs.usda site says a teaspoon of productive soil can contain between 100 million and 1 billion bacteria. The vast majority break down organic compounds so that other soil life can make use of them.

Disease organisms are already in your soil, and your plants are more likely to be infected by rain splashing dirt up onto the leaves than by vegetable matter buried in the soil. If you encounter diseased plant material you should put it in the trash; don't compost it. But dead plant material does not inherently encourage plant disease. Animal manure from cattle, horses and sheep should be composted before application to prevent urea damage to plants, but it is not contributory to disease.

"Animal manure from cattle, horses and sheep should be composted before application to prevent urea damage to plants, but it is not contributory to disease."

Actually animal manure can be quite contributory to disease........ecoli, salmonella, and listeria are all common in fresh manures. As are any number of parasites, including roundworms and tapeworms. It is always suggested to compost any animal manures before applying to a veggie garden or to edibles. Or age it for a suitable length of time.

Interesting question.

I’ve done that a lot over the years and never worried about it. Occasionally animals dig it up even tho meat or bones are never used. It just has to be chopped up and mixed in well to discourage animals. If worried about the nitrogen issue, try to bury as far as possible from roots. Vermicomposting is fun too.

gardengal48 is correct about uncomposted animal manure and human disease. I was thinking about plant diseases not being an issue. Certainly you don't want these bacteria resident in your garden bed. Studies show that they can survive in a garden bed for a year or so, and are extremely common in animal manure. There are some indications that they can actually be taken up by produce, though in general such bacteria are not incorporated into plant tissue. But they can certainly coat the outside of it. Interestingly, washing is pretty ineffective in removal of e coli from the surface of greens.

it has never been an issue for me. if I have something, I dump it under some plant that is tall enough to cover the sight. if it is the cold season I bury it.

Yes, trench composting is one flavor of in-situ composting. It's slower than pile composting because of poor ventilation, but a lot easier. Just bury and walk away.

Thank you for the responses everyone. From how I interpreted, they meant disease in a way that it would hurt your plants rather than the type that would hurt you like in the case of ecoli.

I have to assume that when you dig organics into soil, you get increases in all bacteria, including those that might harm plants. So I suppose there might be some truth to the idea that composting greens could produce a lot of plant pathogenic bacteria along with non-pathogenic bacteria. These bacteria can survive for many years in soil, and one has to assume that the way they survive is by digesting residual organics there.

hugelkultur does not tie up nitrogen. read up on surface to volume ratio.

Ah, but it does!! Any wood left to decompose in the ground will tie up N. But the surface to volume ration does come into play as does the depth the wood is buried. Hugelkultur wood is generally sited pretty well down in the soil profile as well as being covered with a depth of soil that will generally exceed the penetration of most annual vegetable crop roots. So while there will be some N unavailability, it will not be where it affects the plants you are growing.

"From how I interpreted, they meant disease in a way that it would hurt your plants rather than the type that would hurt you like in the case of ecoli."

Allowing vegetative or kitchen waste to decompose in situ or buried (rather than composted prior to application) will not produce bacteria or fungi that will be harmful to the plants you are growing.....unless you are already eating diseased veggies you purchased :-) What will be produced are the decomposers and they do not affect living plant material.

Decaying wood will tie up nitrogen, though logs and branches decay slowly. Maybe that's what you mean by surface/volume. Logs and branches don't have much. But also, as I understand it, hugelkultur puts logs and branches well below the root zone. So if they are tying up nitrogen, they aren't doing it where the roots are. By that token, they aren't really amending the soil where the roots are either. At least not for a few years. I've never quite figured out the benefits of hugelkultur, but certainly for cold climates, the heat released at depth can lengthen the growing season. As the logs and branches degrade and very slowly release nutrients, those nutrients will be leached downward, and not upward to where the roots are.

Surface/volume refers to the simple point that decomposing microbes that would need nitrogen to break down the wood are mostly limited by the physical surface area. So at the extreme, sawdust will have tens of thousands of times the surface area of a log of same volume; chipped wood less than sawdust, but still a lot. It gets broken down more quickly but all those bacteria need nitrogen, and they use up everything nearby - temporarily. (Nitrogen availability may be a limiting factor in this process - hence why urea and other forms of nitrogen added to speed up the process by some). The log would break down more slowly, less nitrogen tied up.

It would also be more by means of fungi getting in there, and some likelihood that means less nitrogen tied up, but kind of speculation.

I did some reading on hugelkultur and, in most of the references I found, it was recommended that nitrogen be added BECAUSE hugelkultur does tie up nitrogen. But I agree that compared with high surface-to-volume organic soil additives, it probably won't tie up that much. As far as I can tell, the main value in hugelkultur is getting rid of logs and branches. If I could pulverize those logs and branches, I'd just compost them and mix that compost into my soil instead.

Yes, the whole question is whether or not the tie-up of nitrogen interferes with plants taking it up - if the nitrogen 'use' for breaking down the wood is slow enough, it won't be a factor. There are other factors of course - how much nitrogen is in the soil already and how available, air available and presence of nitrogen-fixing microbes, etc. Fungi are known to move nutrients around through mycelium - can they bring nitrogen in?

Some of the claims about hugelkultur are that (compared to burying already composted soil amendments) it can last a very long time and the slow process contributes to a longer-lived soil bioweb, better drainage/water buffering (wood can absorb and release a lot of water - at moderate speeds), etc. And also that breaking down slowly has a beneficial impact on nutrient cycling and availability (less just gets washed out, as well as lowering the nitrogen tie-up). May be better in some soils than others, your mileage may vary, etc. It is also a decent way to get rid of wood and branches )).

I'm not trying to push hugelkultur, but there are some decent reasons it may be different than tilling in other organic matter/compost or mulching with woodchips.

Thank you. That makes sense. In principle, hugelkultur offers a soil structure that is less temporary than just digging in compost, because composted wood is being added gradually over many years. Also true that buried wood will probably improve soil hydration and mitigate nutrient leaching. But if you start out with poor soil, hugelkutur sure isn't necessarily the best way to improve it fast, and nitrogen management becomes somewhat iffy.

I doubt there are any single magic bullets for poor soil, but some people report good results. Obviously may depend on conditions, and no-one is saying that different methods can't be combined (like continuing to mulch/add organic matter later). I expect may be more relevant in climates where organic matter in soil is depleted fast, or clay-type soil where you need to get something under and in the soil - but I haven't seen any serious studies of where it's best used. Frankly I don't think it's really practical for large-scale application (commercial agriculture), and most gardens don't get studied in as carefully controlled conditions.