DIY Compost Starter: Step By Step Guide To Making Your Own

A whopping 1.3 billion tons of food has been wasted last year. Let that sink in for a moment.

This number is equivalent to a third of global food production. It’s clear as day that the way we treat waste has become utterly unsustainable – and something needs to be done. 

Of course, major industries and governments still got their work cut out for them. The fair share approach to food and resources requires a major shift in both the system (government and industries) and mentality of us as humans, and until then, we could at least contribute to the waste reduction by composting, as individuals. 

New research by Thünen Institute of Rural Studies, Germany suggests that nearly half of the food waste we put in our garbage bins can be composted. In order to make the situation better, we should be very mindful about the quantities of food we really need to prepare/cook, thus making sure there’s no unnecessary waste left behind. Additionally, by utilizing dry composting toilets, we can further contribute to reducing waste and regenerating soil. 

But surely, since you’re reading this, you don’t need lecturing and reminding of the need for waste reduction. You’re looking to further improve your composting skills, and this blog post will help you do just that.

This step-by-step guide will help you learn how to catch, grow (cultivate) and make use of local microorganisms that naturally inhabit the space around you. Microorganisms help us decompose humanure faster, prevent odor, and ultimately, help us in the process of making a richer and healthier final product:


Why should we compost?

Around 5 to 7 million hectares of topsoil – which is of extreme value to agriculture – are lost every year to erosion and degradation. Overgrazing and deforestation (and bad agricultural practice) leave the land prone to erosion. 

Composting paired with humanure composting reintroduces nutrients and beneficial microorganisms into the earth, contributing to restoring (or upgrading) the current state of fertile soil mass.

What can we compost?

For those of you who are already familiar with the process of composting, this might be unnecessary info. If that’s so, feel free to skip to the step-by-step process for compost starters. If you’re somewhat new to the whole concept, we’re going to cover the basic info, just in case. First of all, all organic matter can be composted: kitchen waste, garden waste, yours or your animal’s poo – you name it! On our earthship, we use a combination of organic kitchen waste and human waste that comes from our dry composting toilets.

To be frank, it’s impressive what we get from our composting chamber. By combining the two, we’re very proud that we’re able to close our waste loop and help people around the world to do the same.

Why all the fuss? Healthy soil really means healthy people. We know it sounds over-sentimental, but changing your habits can be immensely beneficial to our planet – and we’ve got the equipment to prove it.

Composting Starter 101

When starting a new humanure pile or bucket in your toilet, it’s nice to add a starter culture. Starters are concentrated colonies of microorganisms in a small amount of their food. They are essential for the humanure composting process and they will occur anyway. By adding this concentration you are just giving a kickstarter and accelerating their process of growth. 

Simultaneously, they’re good “maintainers” too, meaning they will maintain the composting process from start to end.

 When there’s a funny smell even after mixing/adding more air, or you have a faster filling than usual, it might be a good idea to start adding some microorganisms.

If, however, you need it done ASAP, the fastest solution (without purchasing a microbial compost starter) is to add a handful of forest soil. That’s the same topsoil that we are going to use in the cultivation process. 

IMO or Indigenous MicroOrganisms are naturally occurring microorganisms in the soil in every corner of the planet. Capturing and cultivating your own local (indigenous) microorganisms is not a complicated process, and also, it’s free.

The steps you need to take

Here’s what you need:

  • A box (preferably wooden, but plastic is acceptable too)
  • Handful of rice
  • A handful of forest topsoil (we literally mean using your hands, no shovel needed. Keep the dry leaves you find as well)
  • Thin cotton cloth
  • A plastic bag (preferably home compostable

compost starter essentials

Preparing phase

Next, you need to cook the rice al dente and let it cool. After cooling, place it in the box. Cover the box with a cotton cloth. This will prevent the dirt and leaves from falling into the rice, while at the same time allowing microorganisms to find their way into the rice. Tie the cloth so it’s sealed tightly and wrapped around the box (we recommend using a rubber band).

Once you’re done, place the forest soil on top of the cloth (again, it’s fine if there are some leaves there). Pack it nicely in the plastic bag leaving air inside (like a balloon). The plastic bag serves to keep the moisture.

compost starter preparing phase

Resting phase

Once your rice is nicely wrapped and packed, keep it like that at room temperature in a shady place for 4-5 days. During this period, do not mix it or add anything else – it’s a resting phase after all. After those 4-5 days have passed, go and check out on it – but do not mix the rice.

By now, you should be able to see “foam” building its structure resembling a thin spider web. During this time, open the bag, allowing new fresh air in.

compost starter foam

Note that the color shouldn’t be any other than white (other colors indicate the growth of less effective fungi). Unfortunately, if the foam isn’t white, you will need to redo the whole process. 

Final phase

After around 7-10 days, you will notice a thick white cotton-like foam that has overgrown the rice. Usually, the indicator that the composting process went according to plan is the sweet milky smell.

 And voila! That’s it! You can divide this amount using your hands into smaller chunks and place them on the bottom of your bucket or chamber. Or simply mix them in your pile outside or indoors (wherever you keep it).    

final phase compost starter

Bonus recipe for the outside composting pile

We got this recipe from one of our customers. In fact, saying that this customer is enthusiastic about composting would be an understatement.

Although there are many methods that are equally effective, we wanted to include this one in particular because it raised our eyebrows as well. Considering we are equally passionate about the contents we leave behind, mentioning the method was a given.

My idea is that the potential pathogens in human poop are completely consumed by this deeply vibrant microbial activity, so we don’t need heat from a hot anaerobic pile (like pasteurization) or raw time (like the more traditional simple humanure meta).

This compost can be used for 12 months tops after the box is filled to the brim. Our method meta is one of maintaining a long-term low temperature for the deeply aerobic microbial colony. 

Yes, the colony is fed poop without urine. This is critical because when poop mixes with urine it becomes toxic to most benign microbial species, plus the very high nitrogen content in urea can easily ruin your compost C/N ratios.

But that’s not all! The real kicker is that the colony is also fed kitchen scraps, green grass, garden clipping, bio-char, a dash of mycelium containing commercial compost, local living humus (for inoculating with local microbial colonies), and even, in our case, liquid kitchen waste. We collect kitchen waste and then pour it over each new layer of compost, both for moisture and the concentrated nutrients inside.


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