On October 17th the City of Greater Sudbury in conjunction with Earth Care Sudbury sponsored a workshop on composting at the Ward 1 Delki Dozzi Community Garden. Participants were shown compost bins that had been set up recently and the rationale both for their construction and for their placement. Participants viewed a power-point presentation that provided an overview of both the science and the art of composting. Participants then returned to the compost site to find that Delki Dozzi gardeners had stripped the vegetable beds in preparation for winter and had completely filled a one cubic metre compost bin.
This morning one of the gardeners undertook the next stage in the composting process by building the compost pile to optimize the rotting process. First, the vegetation that had been stockpiled in the bin was piled on a tarpaulin and bit by bit chopped up with shears. This process results in comminution (‘comminute’ is a fancy word that means ‘to make smaller’) and this has the effect of increasing the surface are of the vegetation that can be attacked by decomposing fungi, and bacteria, and possibly some plant eating insects and other arthropods.
A layer of the chopped up material was spread in a bin in a layer about 10cm deep. This was then followed by an equal layer of un-decomposed material that was left over from the previous year’s composting and that had not yet rotted completely. This material not only gets a second chance to become compost but also it provides a source of decomposer organisms that have been hanging around waiting for the right conditions of moisture and temperature.
The next layer added was pond weed from the shores of Lake Ramsey. Cleaning up and using aquatic vegetation in a compost pile serves two purposes. First it reduces the amount of fertilizer entering the city water supply by harvesting before it rots; and second, it provides nutrients for our garden free of charge. How cool is that? You get someone else to buy your fertilizer for you when they cultivate their lake shore property and you help keep your water supply in good shape when those nutrients seep into the lake and are taken up by the aquatic vegetation.
The sequence of new vegetation, old vegetation and aquatic vegetation were repeated until all the new vegetation had been processed. It is interesting to note that the fresh vegetation just removed from the garden beds plus an equal amount of old vegetation and aquatic vegetation did not quite fill the bin. This demonstrates the importance of comminution; not only does the process increase surface area but eliminates large air spaces that would cause the heap to dry out. You need enough air but not too much; you need enough moisture but not too much.
Nothing much will happen in the way of decomposition this fall and winter but come the spring thaw, longer days and warmer temperatures, the gardener will turn the pile over into an adjacent bin and composting will begin in earnest.
All materials at hand and ready to begin.
Aquatic vegetation rich in goodies