Is Hot composting Possible With Smaller Compost Bin?

Forgive my ignorance on this if you would, im pretty new to the gardening world.

I have tried a number of compost bins with varying degrees of success from the council supplied to metre squared wooden bins and even a tumbler bin (which was completely useless by the way).

Right now, i am able to make reasonable compost in the metre squared compost bin but most of what i have to fill it, is grass clippings and Im afraid my garden is not that big. In fact, the grass clippings probably only fill about 8 inches of the bin when all is said and done albeit before I add some cardboard to the pile of grass clippings. As there is only me in my house, I do not generate a lot of kitchen waste though what I do generate is put in a bokashi bucket and later shared between the compost bin and the 2 wormeries that I am currently running.

The metre squared bin does work but it takes about a year for everything to break down. I can live with the length of time that it takes but the problem is the speed at which weeds suddenly appear from that compost because the compost heap is a cold one?

I read somewhere that much of the success in composting is down to the surface area of the heap, does anybody know if that is true? Or is it actually possible to get a hot compost pile from something like the aerobin which is smaller in size (74cm x 74cm) and insulated? Its very expensive. I dont mind spending the money on it if it is going to be successful but I have no idea if hot composting is even possible for the amount of garden waste that I tend to generate?

Any thoughts at all?

 

I suspect that the answer is no. Essentially it comes down to critical mass. As the size increases the heat generation will increase (proportional to volume - ie cube of size) relative to the heat loss (proportional to surface area - ie square of size). The Moon Gardener (John Harris) in his book talks about needing a ten feet cube heap to get really hot.

Insulating the container will help - but I suspect that there is a limit as to how much.

 

Thanks Peter. Thats what I suspected.

I guess on the positive side of that bin, it would at least keep the area sealed so keep seeds from birds and so on out. On the other hand, that may also prevent various critters like woodlice and so on getting in there to do their job... Difficult sometimes to know what to do for the best LOL [hr]
Looks like aerobin is not very successful for many people anyway from what I am now reading.

http://www.gardenexpress.com.au/forum/viewtopic.php?f=2&t=9025

The mere fact they have removed their support forum from the site tells me all i want to hear LOL Guess i will go back to the cheaper second wooden bin and just keep the thing covered :-)

Thanks Peter, that was very helpful

 

Hi Andy,

I can see the problems there. Couple of thoughts, bacterial activity is highest in spring and autumn, so if you can save the different materials for those times then mix them you stand a better chance of it turning on.

I've just emptied a 50 gallon barrel of kitchen waste to line my bean trench. Because it was airtight (we got rat problems) Not much had rotted down, most of it was still recognisable, so it is possible to save a years worth of scraps.

You'd then build a heap by putting layers of scraps,lawn clippings,any dry stuff and so on.

Second thought was to add an activator at that stage, water it over with a high nitrogen solution, this could be chicken manure soaked in water or just watered down saved up wee wee.

Cover it to keep rain out but still let air in. Stick a metal rod in to test the heat, after 3/4 days, if its gone nuclear, then the end should be too hot to touch.

The other solution to the weed seeds would be to sterilise it.

 

What Ziggy says makes good sense. But I still see this as a problem in physics. Its very similar to an atom bomb. Neutrons are created in proportion to the mass involved, but are lost (like heat) via the surface area. Very small atom bombs don't work. Only when you get above a critical mass where neutrons are being created faster than they are being lost do you get any real heat produced. And when you do its a lot.

On a similar subject. Three or four years ago, I went with a friend to a local timber mill to buy some wood chips. We were directed to a massive pile some 20 feet high and 100 feet long, and told to help ourselves. What I remember most was the clouds of steam arising from this pile. We filled bags with the bark chips, but had to stop and move away every few minutes, because it was too hot to work continuously close to the pile. I was expecting the whole pile to burst into flames at any minute. Critical mass.