Food waste to fertilizer: making compost at home
Updated: Sep 3, 2022
Did you know that Americans throw away ~ 10 kg (~23 lbs) of food every month, the equivalent of up to 28 percent of the food in the United States never being eaten? And those of us in Europe are just as bad: we are throwing away ~ 14 kg (~30 lbs) per month. Then, to make it even worse, most of this wasted food is hauled great distances in carbon-emitting trucks to landfills, where it essentially rots and generates methane, a greenhouse gas that is up to 86 times more potent than carbon dioxide. All bad, right? And relatively easy to resolve. Trust me on this one; it's easy.
Let’s start with the certainty that we will never go to zero food waste in our households - never. (We will tackle how to lower the amount of your food waste in a follow-on blog.) Most households end up with at least banana peels, kale spines, eggshells, and dead Mother’s Day flowers, etc. So, what can we do with those unavoidable food scraps? How do we upcycle our food waste into a food resource? There are many creative ideas on that (again, another follow-on blog with details!), but ultimately, some amount of food is just going to be "waste" and thus can be composted.
Let’s start with the certainty that we will never go to zero food waste in our households
There are many ways to compost at home. That might look like hiring a composting service – if that is right for you and your budget; there is no need to feel obligated to do this yourself. Or that you set up a composting system at home. We will discuss the latter in this piece, but feel free to reach out to me if you need help finding the former.
A dedicated unit for the first stage of composting: accumulating your food waste. How much food waste you accumulate, how much time you can dedicate to composting, and the location of your composting system will inform what type of device you use.
Use a bin like this if 👉🏾:
You generate quite a bit of food waste per week b/c you are a large family or are a vegetarian (my food waste increased significantly when I became a flexitarian). We keep ours under the sink, but some people have attractive ceramic ones which they keep on their countertop. And before you ask, as long as you empty the contents ~ twice a week, you should not have an odor or insects.
Your ultimate compost pile is nearby, like in your backyard.
You have a worm compost unit.
You practice Bokashi composting (more on that in a later post).
Store in the freezer if:
You have less food waste and can accumulate it in your freezer in a plastic bag or container.
Your ultimate compost site is far enough away that you would only go once every two weeks or so (such as a community composting site several blocks or km away). In that way, your food waste is not rotting anaerobically in the bin, stinking up your kitchen, and attracting flies (no faster way to decide you don’t want to compost!)
What to compost:
For beginning composters, keep it as easy as possible. You don’t want to become discouraged, and as composting is an art and a science, there is a balance to doing it correctly. Simplifying your input is a reliable way to ensure you will keep doing it!
Basically, the creators of compost (microbes & worms) need the following to make compost.
Nitrogen AKA “Greens” for protein and amino acids, essential elements for biological growth and to speed up the decomposition process. Nitrogen comes from what composters call “greens”: fruit and vegetables such as kale spines, apple cores, coffee grounds (yep, coffee grounds and tea bags are greens!), and cauliflower stalk ends (check out this list of greens for more examples). To help the microbes with their work, cut the scraps into ~ 5 cm pieces. And add half as many greens as browns in your pile.
Carbon AKA “Browns” for energy (think food) enabling the decomposers to work. Carbon comes from dead leaves, branches, paper towels, egg cartons, and newspapers. The latter should also be cut into strips and small pieces with twice as many browns to greens.
Oxygen 💨 for aeration. You can ensure enough oxygen by periodically stirring your pile (every month or so).
Water 💦 for biological production. Make sure your pile is as damp as a rung-out sponge. If it is too wet, it will just degrade like spoiled food (yuck), and if it is too dry, it won’t decompose promptly.
Your job is to ensure that there is a balance of the above in your composting bin, whether that is a tumbler, a three-bin open system, or a closed unit. I won’t go into the details of the different types in this blog but check out NRDC’s how-to guide to see the possibilities.
Benefits of composting
More carbon is stored in the ground making the soil more nutrient-dense = what grows in it is nutritious ✅
Soil retains water better ✅
Less carbon and methane (aka greenhouse gas) emitted via transport and from landfills/incinerators ✅
No waste – everything is recycled, indeed even upcycled! ✅
Ready-access to nutrient-dense fertilizer for your garden and house plants ✅
If it becomes too burdensome, figure out what you can do to make it less so: maybe you don’t cut up the scraps, maybe you don’t crush the eggshells. If you don't do it perfectly, so what? Eventually, composting your food scraps will become a habit. For some of you, that might mean full-in, composting absolutely everything every day. For others, you might only remember two days/week to recycle your apple skin peels. We will take all of it and everything in between. Because if you do something now, it is better than not getting started.
Finally, why are you doing it? Why bother?
Composting is good for the climate and for humans! Check out ILSR's composting infographic to see more details.
You are recycling (in other words, not wasting) nutrients that are used by plants, veggies, and fruit in your garden.
You are creating community with like-minded folks.
You diminish food waste – and isn’t that the foremost point?