Composting - Food & Garden Waste
Effective waste management is an important part of permaculture design. We have several methods here on the farm for turning would-be waste into a valuable resource. One of these is our compost tumbler. Our previous composter was beginning to struggle with the volume of food waste we produce. So, on the advice of our friends at @oldtreebrewery, we upgraded to a shiny, new Joraform tumbler! It’s a solid, sturdy bit of kit made from galvanised steel and with a 2inch thick layer of insulation inside. The internal temperature can reach 75 degrees, making short work of digesting all the food scraps we feed it. Reaching such a high temperature also means we can safely compost cooked meat and fish scraps.
It features two bays. We feed scraps into one bay until it’s full then we begin to fill the second bay. Once the second bay is full we go back and empty the first bay and the process starts again. This type of composting works aerobically (with oxygen) as opposed to anaerobically (without). Air holes on the side allow a flow of oxygen into the composter. Giving it a good turn every few days ensures that this oxygen is mixed into the breaking down matter inside as well as thoroughly mixing new and old waste. Aerobic bacteria thrive in the oxygen-rich environment and they get busy breaking down the organic material producing a lot of heat in the process!
We have built this lovely roof over our new composter. This is, in part, to shelter it from the rain, to get as many years of use as possible out of it. It also creates a nice dry space for us to store our carbon source conveniently close by. In any composting system, it is important to have a balance between ‘green’ waste, high in nitrogen, and ‘brown’ waste, high in carbon. We roughly aim for a ratio of 2:1 green to brown waste. Our nitrogen-rich kitchen scraps are balanced out by adding sawdust. As well as adding the essential carbon, sawdust allows small air pockets to form in the wet food waste, creating more space for the all-important oxygen.
When the composter is full, we empty it into a wheelbarrow and transfer it to one of our compost bays. These are made from old pallets and are slightly raised off the ground to allow airflow. Here we leave the compost to continue to mature and break down until we are ready to use it. At this stage, we can also add biochar to the compost. Worthy of a blog post of its own (look out for that!).
Biochar is essentially charcoal that is created in a low-oxygen environment. It can be used to sequester carbon and also aids soil health by improving aeration and drainage as well as water and nutrient retention. We ‘charge’ the biochar, inoculating it in our compost. It acts like a sponge, absorbing nutrients and making it immediately effective when spread on our beds. This stage is essential, without inoculation the biochar will instead absorb nutrients directly from the soil. We mix the mature compost from our bays with the biochar at a 1:1 ratio then leave it to inoculate for at least a couple of weeks.
To deal with our garden waste we use a three-bin compost system. Made from old pallets it features three bays. One is active, this is where we add any new material. Once the matter in the first bay is sufficiently broken down we turn it into the second bay where it continues to break down undisturbed. When this is broken down enough it’s turned again into the third ‘ready’ bay where it can then be used to spread onto beds and add nutrients back to the garden. We added a tin roof over the bays during these wetter months to prevent the compost from getting saturated. Wet compost becomes too compacted leaving no space for oxygen. Equally, if compost becomes too dry it will stop breaking down as the microbes cannot effectively digest the organic matter. Though we have little risk of that in wonderfully wet Wales!