Page 21 - Allotment Gardener Issue 2 2024

C
HOT COMPOSTING
Hot Composting produces compost more quickly and will kill weeds, seeds and pathogens. However, it involves a little more work and the bin will need to be larger (at least a cubic metre) to help retain the heat produced by the composting organisms. Most hot composters will turn their hot compost bins regularly for the first month, which is easier if they use a bank of three or four bins moving the waste from one bin to another. Pallets are often wired together to make low- cost bins. Rather than using the ‘as and when’ system for adding the materials – as used in cold composting - when hot composting,
the bin should ideally be filled in one or two batches, which means that the waste may be needed to be stored on the site for a few days before mixing.
Layering greens and browns is a common method of visually estimating the C:N ratio by adding greens and browns to the bin in separate alternating four-to-six-inch layers, which will be mixed when the contents are turned.
Regularly aerating the bin contents by turning during the first few weeks results in
increased microbial activity, generating temperatures of 40 - 700 C which kills the seeds and pathogens. Turning to maintain temperatures every two days for 18 days can produce immature compost in as little as 21 days or with less frequent turning
in two to six months. On our community allotment site, we turn new bins weekly for
3 or 4 weeks. Others will turn the contents when the compost temperature drops below about 500C until it stops rising after being turned.
over wintered content looks wet and smells unpleasant, more browns can be added to restore the balance. Woodchip is an effective remedial brown, as in addition to providing carbon, it helps to create the air spaces required for aerobic decomposition.
If excess leaves, or other browns, were added to the bin in the autumn to help provide insulation, the contents might be too dry and additional greens will need adding to restore the green brown ratio. Coffee grounds, manure or grass from the early lawn mowing are all good activators at a time when many other green materials are not available.
When cold composting, be prepared to wait for about a year for nature to work her magic and produce the compost, so more than one bin will be required on the allotment. The bin
contents will sink as the waste decomposes, allowing more material to be added. In addition, the contents should be kept moist by occasional watering. The material will
break down more quickly if cut into short lengths, to expose a larger surface area to the composting microbes. Having short lengths also make it easier to turn the bin contents
to aerate and speed the composting process. Brassica stalks can be chopped into short lengths and crushed with a hammer which will speed their breakdown and relieve your stress. Most allotment composters will use several of these bins, filling the first and then moving to a second or third while the contents of the first bin are composted.
Rod Weston is an organic master compost expert, who operates a composting demonstration site with over 30 composting bins, wormeries and cooked food composters at Stokes Wood Allotments in Leicester. He runs our NAS composting
Facebook group and is also author of ‘A Gardeners Guide to Composting Techniques’ published by Crowood Press.
Allotment Gardener | Issue 2 2024 | 21