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.
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!
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.
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 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!
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