Probably More Then You Want to Know About Compost
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Gardeners of all levels can benefit from composting and creating that "Gardener's Black Gold". There are many different methods of composting and although most of us know we throw in green waste such as garden clippings and kitchen scraps with brown waste like fallen leaves in a pile then we get nice compost, do we really know how composting works? There are many different methods for composting and each have their pros and cons, however the process of decomposition is the same for each method at the core.
Decomposition of organic material is a natural occurrence. When leaves and plant life fall to the ground in the forest, teams of micro organisms break down the plant material into smaller and smaller components until the end result is nutrient full material called humus aka compost. The humus returns the nutrients back to the soil for other living plants and trees until they die off and the cycle continues. This is the natural cycle we want to escalate by creating the ideal "meal plan" and environment for these micro organisms.
As soon as you start your compost pile, millions of bacteria and fungi start the process. They break down the material feeding on the carbon for energy and nitrogen to build protein in order to multiply. All this work creates heat and the pile will heat up. As the compost heap heats up, the bacteria and fungi that started the process will begin to die off. This is a good thing because each stage of decomposers work within specific temperature ranges and when they die off they become food for the next stage of decomposers and so on until the job is done.
Bacteria that start the process are called Psychrophilic bacteria and are most active about the 13°C (55°F). They do function below this temperature but in increasignly slower rates until the freezing mark at which point decomposition pretty much ceases. The Psychrophilic bacteria are there to do the prep work and get the pile up to temp.
The next stage kicks in with Mesophilic bacteria. Mesophilic bacteria does most of the composting work between 8°C and 50°C (46-120°F). These guys produce acids, carbon dioxide and more heat until they create an environment they can't live in and die off for the next stage of bacteria.
At this stage, Thermophile bacteria comes in and feeds furthering the decomposition process. This is the last stage in bacteria and fungi process. The ideal temperature at this stage is 50°C-90°C (120-194°F). The Thermophile will work at the pile until there is no more material left for them to break down, at which point the heap temperature will start to drop and the maturation stage starts.
The maturation stage is what we can see visually when we turn the compost pile. We see larger organisms like worms, ants, centipedes, millipedes, etc... Once the pile is completely broke down where you can no longer recognize any organic material and the compost has a nice earth smell to it, it's finished and ready for the garden.
It's worth noting that the stages above are in perfect composting conditions. Our backyard compost heaps will rarely get to the high end Thermophile stage. This is why it's not recommended to compost diseased plants, dairy products, oils or animal materials, which require a constant temperature of approx 60°C (140°F). Even without reaching these temperatures, our backyard heaps will break down nicely, just take a bit longer. Our job is to help speed up the process by giving it exactly what it needs Oxygen, Organic Material and Water.
The various stages obviously don't happen all at the same time within the entire compost heap. Heat will build up from the core of the heap and propagate outwards, but we speed up the process by turning the pile about once a week. Turning the pile adds oxygen and distributes the heat throughout the pile evening out the decomposition process. It's also important while turning to verify the moister of the pile. Rule of thumb is it should be as most as a wet sponge. If it's too dry it slow down the process and if it's too wet it will invite anaerobe bacteria which causes a smelly compost pile. If it's too dry just water it down and check it again the following week when you turn it. If you live in an area that gets a lot of rain it would be beneficial to have your compost pile up off the ground, like a pallet bin propped up on cinder blocks. This will ensure proper draining and a tarp on top of the pile will stop it from getting too wet.
Composting is one of those things that can be as simple or complex as you want it to be. For me, I started small with a home made pallet bin, but as my experience is growing, I'm going to build a 3 bin so I can create more compost easily. You don't have to be fancy, you just have to start ;o)
Permaculture
