Municipal Compost

Municipal Compost is compost made directly from organic waste, rather than for example compost derived from peat. It is often used as a 'soil conditioner' rather than a straight compost due to its high nutrient content. The process of making it helps keep organic waste from going to landfills and also produces useful byproducts - gas and heat.

‘My overall feeling is that if you can get municipal compost then it’s worth using it somehow. That might be as a straight soil improver, mixed (after sieving) with leafmould to make your own potting mix, or mixed with bought-in peat free to make a rich mix for containers. I wouldn’t recommend using it on its own in containers, unless you’ve done a test run and found it works (I think all gardeners should be having fun with their own trials, which would also help build a much clearer picture of how these ‘municipal’ materials are doing). Use it to complement other composts/materials because it helps reduce landfill and has a much smaller ‘footprint’ than say peat-based compost.’ - John Walker

How is municipal compost made?

Food waste and green waste from gardens – grass and hedge clippings, prunings – is roughly shredded (to a width of 400mm) and then mixed with a small quantity of compost activator (contains micro-organisms and enzymes to promote efficient composting). This mix goes into a large, enclosed tunnel. Fans under the floor, blow air through the waste. The pile heats up as it begins to decompose, and the temperature is carefully monitored with probes.  It must reach 60 ^oC  for at least 48 hours so that pathogens and most weed seeds are killed. After a minimum of one week in the first tunnel, it is turned and transferred into a second tunnel, where the process is repeated. This helps ensure that the materials are thoroughly and evenly composted. The compost is then transferred out of the tunnel, mixed with other batches (to help minimise  inconsistencies between batches), and left to mature for several weeks. The final step is to sift the compost through a large drum – removing anything larger than 20mm.

The EcoPark in North London distributes 60% of the finished compost to agriculture, 40% to community groups and allotments. The normal delivery size is a whopping 15 tonnes, the smallest is 7 tonnes. Plans are afoot to introduce 1 tonne bags this year. This willl be a boon for smaller growing projects.