Good starter plants for hugelkultur beds, and also, compatiability with fruit trees

So I'm helping out at a local Community Farm at the moment, and the owner has worries about the regular droughts that we have here in Queensland, Australia. In the dry spells, we can go up to 6 months without a drop of rain, meaning that the fruit trees and orchards usually have to be pump irrigated pretty much every day in order to keep the trees alive.

I'm suggesting hugelkulture as an alternative to that, and wanted to run past my idea with the forum. My idea was to build circular hugelkulture beds around the fruit trees, at a height of about 6 feet, in order to soak up loads of water and allow indirect watering of the fruit tree next to the bed. My idea was to place the beds around the tree like this (sorry about the simplicity of the drawing!!!)

_____
/.......\
|...o...|
\____/

With the lines being the hugelkultur bed, and the o being the fruit tree. The ...... are empty space, as are the empty space.

We would then have a method of infinite irrigation for the fruit trees via misting from the beds, new space to grow crops on the beds, more protection from grazing animals, and general all over awesomeness.

Can anyone see a problem with this? Has anyone done this before?

My second part of the question was - what are some good initial root-heavy crops to plant in the beds? I want stuff to be planted that has a good solid root system so it holds the bed together and does not collapse onto the fruit tree, but not sure what good initial crops to plant in the beds. Thanks in advance!

All the best

Ollie

I understand that planting trees in a hugelkultur bed is a bad idea because tree roots really don't like air pockets. Your idea seems like a really clever way around that limitation. The only potential problem I see would be access to the center... depending on how high the bed is.

Check out this current topic for ideas on first-year hugelkutur crops.

Yeah, I understood from a number of posts in this forum that planting trees on the beds is a bad move, so we are avoiding that one completely. We have decided to place the beds in a 'U' shape around the trees, with enough room to walk around the tree once it is full grown, and walk around the beds too from the inside and out. Drainage will be provided by a runoff through the gap of the 'U' shape by placing a slight slant on the soil inside the 'U'.

We actually started constructing the first one last week, but we have calculated that we need 2 truck loads of wood and 2 truck loads of soil per tree. And there being 100 trees, this will take a real long time. I took some photographs (and will upload them tomorrow) so everybody will be able to see what I mean, and put an image to my theory. I cannot see a problem with the way I have laid this out, and it might provide a great no-work irrigation system for thirsty trees in dry areas, as well as fertile beds to plant plants that compliment the tree and taste great

Queensland's climate seems to be doing even more bonkers than the trest of Australia's
While you have a big dry, you generally have a massive wet, right?
Clay, sand or....?
I can only go by my own situation: my hugelbeds are modified for my dry, sandy environment: more below than above ground, and as things get drier round here (as I expect them to), my beds may well become basically sunken.
I have my fruit trees espaliered right beside my hugels, all on a N-S axis . My place is pretty small and one tree could easily eat an entire hugel if I let it.
I chuck enormous amounts of mulch around, and I think making sure trunks are clear is vital to avoid collar-rot.

I've only been here for about 4 months to be honest....I'm originally from a temperate climate in England, UK, so i have not even lived here for a whole season! But from what I can gather this is a subtropical area, which has a wet season and a dry season, both in the extremes. There will be mad amounts of flooding at one point, then months without rain for other points. It is certainly in the extremes, and with global warming providing more extremities, it is only going to get more volatile.

The soil on the farm is between clay and earthy soil. Once you dig down a bit it is very clay based, but the topsoil of about a feet is pretty good. We have a never ending supply of manure and mulch and timber at the farm, so soil improvement continues all the time. We are going to just place our hugelkultur straight on top of the existing grassland and see how it fares. Mainly we are doing this so we do not interfere with the root system of the fruit trees that are going to be encompassed by the 'U' shape of the wood.

I'm planning on having my own 30-50 acres property in Queensland/New South Wales at some point in the next 5 years, so this experience with drought-protection-irrigation-systems will be invaluable when I have my own place. It'll be interesting to see how this season feels to me, since I am used to the UK based set 4 seasons, which are pretty defined (except in the last two years....man, they have been all over the place)

I would have a concern with completely encircling your trees with the beds due to the access issue already mentioned and the fact you may have soil that will become waterlogged during the wet season. This could possibly drown your tree roots. I would do some drainage testing before you go to the trouble of building and planting.

I think the drainage is going to be ok, we had a look just after about 15mm of rain (in one night!) and it was just as well drained as everything around it.

I've actually built one of the beds already - the plan is to build two, and see how the go for a season, and if they fare well then we will be building 100 more. I will update with a lot of photos and explanations soon (need to grab a new card reader)

I would do at least one buried swale there as a test and control....

Hegels do trap some water, but if you bury the wood a couple feet down, it will trap water, and pond it down into the wood, while allowing overflow to quickly float away.
Hegels will also keep roots from getting water where they are stacked, and encourage roots to grow up into them. increasing capillary outflows in drought, and making em more susceptible.
They were designed to use in deep old growth forest, to get dead wood out of the way, get some more sun, and to elevate and get some dry toes early in the season, while storing water for later

I would do a row of semicircles facing up hill down one row, of buried wood, with low swales to trap water. We are thinking that it may be better to acrape a cone shape outward to send the roots deeper and trap the water further away from the trunk, but don't know if anyone has tried that yet...

a little damage to feeder roots now is a low price to pay for extended water retention and if you can mix in some charcoal soaked in fertilizer tea, you have a 10-20 year plan...