Regenerating our soils is one of the most critical actions we can take to reverse the damage to our climate. The good news is that it is relatively simple to create compost full of the soil food web that restores life to the soil and its ability to sequester carbon.
Pott Farms grows hemp in living soil in order to regenerate health to our environment while naturally providing our plants everything they need to thrive. This past season we established our own thermophilic composting system (see our social media post on what's heat got to do with compost). Here's how we did it and some guidance on how you can, too.
We started by collecting the materials. We cleared an acre of first and second secession plants to prepare fields for the 2021 season. You'll want to gather:
- 60% brown or woody material. This includes dead leaves, wood chips, cardboard, or anything that no longer has its nutrients.
- Why this is important: This material feeds the fungi who help make nutrients available to plants and is crucial for carbon sequestration.
- 30% green material. This includes fresh grass clippings, garden or kitchen waste, weeds, or even other compost.
- Why this is important: This material feeds the bacteria for the longer haul once they have reproduced enough to heat up the pile.
- 10% high nitrogen material. This includes uncomposted manure, legumes such as alfalfa or clover, or blood meal. This is the hardest material to categorize and possibly collect.
- Why this is important: Bacteria love high nitrogen foods and will reproduce more quickly when they are present. The heat caused by millions of bacteria reproducing at once is how the pile heats up and gets going
We use pallets to create our one cubic yard bins on a flat surface with contact to the ground. You can find pallets for free from local businesses that otherwise end up in a landfill after a delivery. Make sure they are stamped "HT" for heat-treated. Avoid pallets treated with chemicals. Simply tie them together with a few pieces of rope and allow the front to swing open.
At home, I use chicken wire to create temporary cages like this.
Compost piles need about 50% moisture, or free water. We achieve this by soaking the materials in compost extract (water that has really good compost steeped in it) prior to building the pile so that there is a good amount of diverse microbial life necessary for decomposition present prior to mixing the pile and who can get to work right away.
We tried a handful of methods and prefer to mix portions of the materials on a tarp before adding to the pile. An easy way to keep proper proportions in manageable batches is to:
- Have 10 equal-sized containers
- Fill 6 with your brown material
- Fill 3 with your green material
- Fill 1 with your high nitrogen material.
Pour that all onto a tarp and mix with a pitchfork.
[Look how happy Carole is! We work joyfully and love our time at the farm.]
Then we pick the tarp up and pour it onto the pile to add another layer.
Once the pile is built, it is important to keep it covered so that it maintains its water level at about 50%. We use plastic salvaged from packaging, extra greenhouse covering, or tarps.
We track the temperature of the middle of the pile and turn the pile once the middle has been above 131 degrees for at least 3 days. To turn, we remove the material from the top 1/3 of the pile and move the material that has been in the middle to the bottom of a new empty bin, breaking up any clumps as we do. We then put the top of the pile that we first removed into the middle of the new bin, and then put the bottom 1/3 of the pile on top, continuing to break up clumps as we go. We do this again once that middle section is held above 131 degrees for at least 3 days, and then let the pile mature.
We also check the moisture level while we are turning the pile, and adding a little water to each layer, as needed to maintain 50% moisture levels. Keep in mind that the microbial life could die or go dormant if the moisture level is too low, or the pile could go anaerobic if the water level is too high. (We'll talk about all the bad things that happen when a compost pile goes anaerobic in another post.)
We had compost ready to use within two months of starting a pile, in time to use on the fields we created for next season (more on that later, too).
These are the basics to creating fully aerobic compost full of a diverse set of microbial life, and is plenty of knowledge for you to get started yourself. I'll continue to discuss composting in future posts including a full introduction to all the various microbial life forms that make up the soil food web and talk about how I use a microscope to determine their presence and numbers.