Composting revisited

Sunday, 02 December 2018

One of my compost domes

My parents were both fervent believers in the power of compost, so I have always had a compost heap of some description since I first started gardening, 35 years ago. I have previously written a blog about composting, but since that time, my ideas have changed on the subject somewhat. In my previous blog I talked about the use of open compost bays and bottomless domes for composting kitchen scraps, but I no longer use either of these methods, mainly due to what seems like a rat plague in our area in recent times. Rats seem magnetically attracted to these sorts of heaps, even when our plastic dome compost bins were weighted down with numerous bricks around their edges. The rats dug tunnels right underneath the bricks to get to the scraps in the bins, which they would then drag out and eat. If it is possible to bury the dome about 8 cm into the ground, this may help (though I wouldn't put it past the rats to burrow that far down) - or put chicken wire across the bottom of the dome before placing in on the ground.

Compost tumbler

However, I have given up the plastic domes altogether, not only because of the rat problem but because they are very slow to produce compost, unless they are tossed regularly, which I never seemed to do, as it is a cumbersome task. I now use compost drums mounted on stands, which are totally enclosed (though they have air vents), thus eliminating the rat problem. They are turned over a couple of times each day, which speeds up decomposition because the contents are being aerated. We produce a small bucket of kitchen scraps every day, which are put into the tumbler. At one stage, I was using bucket liners that were said to be biodegradable, and hurling the bag with its contents into the drum each day. I have found, however, that these bags don't break down as quickly as one might think. Also, the contents stayed in the bags, forming clumps rather than being mixed in with the other material inside the tumbler, and the bits of the bag got caught on the central metal pins of the tumbler. I don't use any liner now and simply wash out the bucket each day, pouring the water onto a newly planted Clematis, on the advice of a gardening mentor, who told me these plants need a bucket of water a day to do well in our climate!

Dual-chamber compost tumbler

If using a compost tumbler system, you really need two tumblers, so that one can be decomposing without fresh material being added and the other being filled with scraps. I recently bought a second model, which has two separate chambers, which could work to overcome that issue, if the capacity is sufficient for the amount of scraps you generate. Because kitchen scraps are nitrogen-rich, I also add carbon-rich materials to my tumblers - including paper from my paper shredder and dead leaves. These leaves can be kept stockpiled nearby the tumbler (a good use for my now redundant plastic compost domes!). For optimum decomposition, there needs to be a balance between carbon and nitrogen materials. Without the carbon-rich materials, the tumbler contents can become very wet and sludgy. This informational website produced by our local council has easy-to-follow information about these issues.

My worm farm

I still have my worm farm, which takes some of the kitchen waste (avoiding citrus and onion peelings), as this produces vermicast, an excellent fertiliser for plants when diluted with water. A worm farm can be a useful alternative to a tumbler where space is limited. The more worms there are in the farm, the more scraps can be consumed. Note, however, that recently the rats ate through the covered vent hole on the side of the plastic top of my worm farm to gain access to the scraps, so I now put an empty worm farm tray at the top of the worm farm with the lid on top of that, weighted down with a brick. A bokashi bucket, described in my other blog on composting, is another option for compact spaces. For those who would like to compost their kitchen waste but don't have the facility to do so, investigate ShareWaste, an innovative website that connects people with scraps to nearby compost bins, worm farms or chicken coops!

My new compost bays

My other compost system is a set of three large, wooden bays to take all our garden waste: grass clippings, trimmings from perennials and shredded prunings (which are put through a mulching machine). We used to just have an ill-defined 'area' where this was done, with no system for knowing where the mature compost was; the new system (actually my birthday present last year!) has a bay for material to be mulched up, a bay of material maturing into compost, and a bay where new material is to be added, until it is full. Every so often, we throw a bag of cow manure onto the pile and toss the heap. The netting over the top of the bays is to deter the resident brush turkeys! These days I am not leaving the compost to decompose completely but am putting out on my garden as a coarse mulch, on a continuing basis, to smother weeds, conserve moisture, improve soil structure and add nutrients in a slow trickle to plants as it breaks down. Adding the cow manure to the heaps helps counteract nitrogen drawdown as the mulch decomposes on the soil. Recently more good news about compost has been revealed: compost added to soils can help carbon sequestration as an important way to offset greenhouses gases. Composting our kitchen waste at home in an aerobic fashion is also important, as if these are sent to landfill, they decompose in an anaerobic environment, producing methane, a greenhouse gas more potent than carbon dioxide.

I have one other set of smaller compost bays where I put grass clippings and perennial clippings, with some added cow manure. This material is tossed regularly and allowed to break down into fine compost, which is what I use whenever I plant anything in the garden.

Over 50 years, my parents converted what was basically sand in their Blue Mountains plot to a rich, dark soil, which supported a beautiful, flourishing garden, all through the use of compost. My current garden was originally sticky red clay, which has improved over time through what must now have been tonnes of compost. There is still some way to go but I feel I am getting there!


Plant of the week
Flowers in January, February, March, November, December.
See everything that's out this month »

My previous blogs at this time of year:
2008
06 Dec
2013
01 Dec
2014
07 Dec
2015
06 Dec
2017
10 Dec

Reader Comments

  • By Bren - 2540 (Zone:10 - Warm Temperate) Monday, 03 December 2018

    Your compost bays are very impressive! I have so much green waste, I don"t know what to do with it; my compost bays are always overloaded and the material tends to dry out rather than breakdown. A mulcher would help; Deidre, what kind of shredder/mulcher do you have? We have had many mulchers over the years beginning with a tiny electric one. Now we have a huge petrol-powered one, which is a Hansa Chipper. It does really make fantastic compost as everything is reduced to tiny shreds, which break down quickly. Deirdre

  • By Margaret - 2122 (Zone:10 - Warm Temperate) Monday, 03 December 2018

    Thank you for all the various methods of containing compost. I have trouble with rats also (never see them) and have resorted to using large black plastic tubs, covered with a lid, for my household waste,with the addition of green waste, etc. Not as good as your methods, but at least I do have compost. With regard to clematis, I have three growing, and flowering well, two being Australian-bred. I don"t give them a bucket of water each day, but will experiment with the suggestion. Your tubs sound a good idea, Margaret. I have already noted that the clematis is doing very well and has lots of buds; perhaps due to my bucket of water a day method! Deirdre

  • By Lloyd - 4060 (Zone:11A - Sub-tropical) Monday, 03 December 2018

    Clearly dogged attention to the process is key - hoping more moisture will help my two tumblers. My three "domes" are slow (being anaerobic, is my guess) but give a very dark rich humus very slowly. Not so much at present - too much carbon is my guess and not enough turning and moisture. Getting the mix right is a challenge - I just mow fallen leaves in with the grass and hope!. Saw that "rough" compost being applied on Gardening Aus and was puzzled - look more like mulch. Adding oxygen by turning seems important plus getting the balance of nitrogenous to carboniferous materials right. My half-decomposed compost is like a mulch and I lay it on the top of the soil as a mulch, and it breaks down over time. The plants seem to be responding quite well to this approach! Deirdre

  • By Colleen - 2145 (Zone:10 - Warm Temperate) Monday, 03 December 2018

    We also had a rat problem with the dome compost. The solution we found was to cut the vegetable scrapes smaller and put in a bucket of water to make them partly rot before adding to the compost. Lots of fungus nats snack on the veges on the water but they are harmless. Then add the bucket of water & veges every week with dry material. Added benefit is keeps the heap from drying out. I have tried tumble compost but as work can"t turn regularly and it dried out on me. An interesting idea, Colleen. Deirdre

  • By David - 2068 (Zone:10 - Warm Temperate) Monday, 03 December 2018

    Recently a used 400L aerobin composter was donated to our Community Garden. Has anybody any advice regarding these? Unfortunately one of the two plastic cones from the "lung" was damaged and they aren"t cheap to replace because the whole lung has to be purchased since the old model cones aren"t manufactured any more. (Currently we"ve got a traffic cone replacing the upper cone.) At Kimbriki the dome type composters sit on a sheet of rigid metal mesh to keep rats out. Much easier than wire mesh The idea of the metal mesh under the domes is a good one to keep out rats. Have no experience of the aerobin. Hopefully the traffic cone will do the trick! Deirdre

  • By Beth - 2257 (Zone:10 - Warm Temperate) Monday, 03 December 2018

    The rats did put me off trying to compost. They actually gnawed through the plastic dome! I have devised a very simple and lazy solution. We have drilled many 4" holes into large buckets (Mitre 10). We remove the bases using a grinder. I dig a deep hole and bury the bucket. The lid is at ground level and is left exposed. I empty my kitchne waste into said bucket and throw in handfuls of dry leaves,chicken or cow manure, and occassionally diluted Go Go juice. The rats and turkeys go hungry. This is a terrific idea, Beth! Deirdre

  • By Janna - UK Wednesday, 05 December 2018

    I"m incredibly happy to hear that tumbling is working for you! We"ve just built three bays, very similar to your birthday ones, but I filled them within 24 hours of them being completed with a very small proportion of our fallen leaves. Still to figure out how to deal with four acres of organic waste, but we"ll get there. How lovely to hear from you, Janna. Hope all is going well. Your tumbler is working very well! Are you able to shred the leaves? We put almost everything through our mulcher and it is amazing how the volume reduces down! Deirdre

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