City of Armadale
COMPOSTING AND STERILISING YOUR MULCH
Composting is one method of killing weeds and seeds in mulch and can be done very
simply just by following the procedures set out below:
•
Heap your compost material into as high a pile as possible and thoroughly wet
down.
•
Leave to stand overnight.
•
Once the mulch is completely soaked through, add approximately 100g
Nitrogen per cubic metre of mulch to help accelerate composting. (Nitrogen
may be in the form of ammonium nitrate, urea or some other source of high nitrogen
fertiliser. The reason for this is to maintain the correct Carbon / Nitrogen ratio. For
efficient decomposition of organic material, a Carbon/Nitrogen ratio of approximately
14:1 should be maintained.)
•
Add approximately one handful of dolomite lime per cubic metre as this is
beneficial and will help to maintain a relatively neutral pH level.
•
Water the lime and nitrogen fertiliser into the pile and leave to stand.
•
Monitor the temperature of the mulch heap with a thermometer. To pasteurise
the mixture, a temperature of at least 68 degrees Celsius should be maintained
for a minimum of 36 hours.
•
If possible, turn the compost with a fork to aerate the mixture while continuing
to monitor the mulch temperature.
•
Make sure the mix is kept consistently moist.
•
Once the temperature begins to fall, the composting process will be complete
and the material will then be ready for use in your garden.
Note 1
This method of composting only pasteurises the mulch. Micro organisms, such as
bacteria and fungi will still be present in mix, however, if the suggested temperature
levels are reached, most of the harmful organisms will be destroyed, while the beneficial
organisms will be retained. This method will also kill all weed seeds.
Note 2
The above process works best for heaps of approximately 3 cubic metres. Smaller piles
would need to be covered with black plastic to achieve the required temperature for
sterilisation.
For further