My design so far is as follows:

A concrete base to be laid on which the walls of each compartment will be built. I've been debating the pro's and cons of a solid impermeable base with my father. He reckons the solid base will A) stop the moisture within the pile from draining away too fast B) make it easier to extract the finished compost. He also believes the concrete base will make the whole structure more stable and enduring. Each compartment will hold one cubic meter. The walls are going to be single brick and unplastered. I was thinking about leaving some small gaps between some of the bricks to facilitate air exchange. Would also cover the piles with large durable plastic tarps to lock in more moisture.

My main concern is how to keep moisture levels sufficiently high, but still allow enough oxygen to penetrate the pile.
The climate here is very dry as we are technically semi-desert and the vegetation consists predominantly of succulent flora. Rainfall is usually very unpredictable, although we often get some in the early summer and then again in the fall/early winter. Droughts are common too.

I've been wanting to make compost here for a while and now that I have my shredder it's all systems go. My current pile, a conventional exposed heap, is located in full sun and gets blasted by hot drying winds all the time. Hardly the most appropriate situation to be composting in given the local conditions :(

Can anyone give me some useful advice?

My 'bins' (made with old plastic swimming pools) are also solid around the sides, and I'll cover it with a tarp to keep in the moisture. I will now and again ram in a metal bar to get some air in it, or use an electric drill and a long auger. But these things are 1.5 meters high, shy of 3 meters in diameter.

In practice though, being lazy, I often go with the theory of let it rot for two years, it will be ready.

But aeration and frequent turning are just as important, so don't make your bins too big. Unless you have heavy equipment (tractor/backhoe) you need to keep your piles small enough that you can stick a fork in them and turn them without hurting yourself, at least once or twice per week. They say a pile should be at least 3'x3' in order to compost properly, but I wouldn't go much bigger than that, maybe 4'x4'. And build near a water source, like a hose or a rain barrel.

When I dump the chicken poop bucket (I clean their coop daily) or the kitchen compost bucket on the pile, I rinse them out and dump the water on the pile, too. Oh, and if you have access to used coffee grounds, they are a GREAT source of moisture in the pile. My big "Earth Machine" plastic bin has heated up and stayed moist much more easily since I started putting in large amounts of UCG. Do you have Starbucks in Karoo?? I don't even know what continent that's on! LOL Any cafe or restaurant would do, of course, as long as they're willing to save their coffee grounds for you.

--Maureen

No idea if it works on my plants but they all seem to grow faster. N=1 though.

A lot of citrus and avocado is grown around here.

My bins are slightly smaller made from pallets. They get plenty of air and they are built on pavers or or thin bricks - a permeable hard base. The base allows for worms to get in - big time during the rainy season - but keeps the burrowing animals and the tree roots out.

I run my bins on 18 month to 24 month cycles. I generally just feed the bin stuff once a month and cover with grass clippings and whatever. After about 3 months I start to see the volume reduce. I can keep feeding forever I think but at some point around a year, I stop feeding and just water. I've usually topped it off several times by then. During the dry summer I'll water a full bin with about 4 liters a day with a watering can. After feeding a bin for about a year, I'll just water for 6 months to a year. Right now with the cooler and wetter weather I'm getting lazy and I am only watering about once a week. The outside parts might look dry but the inside is moist enough.

You've got a chipper so I'm guessing you don't have to worry about large pieces. Your arid climate means your materials aren't going to be too wet so you will have moisture issues and if you're not turning like I'm not turning, the process will be slow.

I like the pavers versus a concrete base because of the worms. If you turn like I used to, you can still sweep up afterwards so less mess and loss.

Yeah let air in through the walls. Keep the bins out of the wind and the sun and you'll go a long way to retaining moisture. I don't like the tarp because of the lack of air. Better a cover that will block the sun and the rain if the season starts dropping too much rain at one time.

Once the bins get some bulk and age they will retain moisture better. You can always piss in them at that point and it will never touch the bottom.

I don't think you'll go too far wrong with what your thinking right now. What is going to work best is what works for the way you do things. Make the process fit with the way you live and not the other way around. If that means it takes a little longer - no big deal. Once you get into regular cycles, you won't notice so much how long it takes. The compost works for you. You don't have to work for the compost.

Don't fuss too much and good luck.

two cents
..

The solid base is a good idea on both counts. Where I live now, a solid base would prevent soil activity from inoculating the pile and earthworms from cold finishing; do you have worms? Not an issue if you always "hot" compost. A permeable base could be superimposed on the solid if needed.

Given the aridity, rain/grey water catchments might be advisable to maintain proper moisture. You will have to look into hazards involved with greywater storage if it can't be used directly.

I'm in South Africa. Sorry for the confusion! We border on a Mediterranean climate, but not so much rainfall in the winter, it's sparser and spread throughout the year, not really concentrated in any one season. Unfortunately their aren't any Starbucks around here, I think they have them in Cape Town. There is a local franchise of coffee shop called 'Mugg and Bean', but the nearest one is at least 150km away :( On the bright side there are a number of restaurants in my hometown, which get through quite a bit of coffee so I can always ask them to save me their grounds. I'm sure they'd be more than happy to.

As far as not having a semi permeable base is concerned. I've thought about that, but I already have a big worm farm, which is housed in a converted bath. Eisenia foetida I believe so I was going to inoculate the piles from that now and again. I tried to do that to my exposed piles, but I think it was way too dry for them, because I dug in there a few weeks later and only found a couple (1 or 2) out of hundreds I'd introduced previously!

My chipper is a great help, like you say rott, I'd probably have to wait for ever for it to breakdown if the pieces weren't reduced in size and I'm a tad too impatient for that! I really don't have a problem with turning my compost once or twice a week if its going to make things speed up that much more. Still relatively young and virile and I could use the exercise haha.

I'm busy saving up for all the materials to build the composting units. I'm relying on my father to help me build it as he is a builder by trade. Need 7 square meters worth of bricks and two bags of cement for the walls. Plus about a square meter of stone chippings and two square meters of sand for the base. Not cheap, but I'm confident it'll be money well spent in time!

It rained for the whole night two days ago so the soil is wonderfully moist and perfect for planting and weeding. Must crack on and make the most of it before it dries out again.

Will post updates as the project progresses! Oh and just so I know is it possible to upload photos to this thread? Or would I need to do that in the gallery?

Alex

Then cut and paste the HTML link into your message

(third one down)

So protea, is there anyway you can fence-off your garden area to keep these Baboons out?

Greg
Southern Nevada

If the pile is too dry, composting stops. If too wet, composting is slowed until the excess water can drain away.

Cinder blocks are permeable enough without adding gaps.

I kind of think the worms will find a way in regardless of what kind of base you use.