How to Make Active Compost Microbes

Marissa Robert

Of all of the green habits you can pick up, composting is one of the simplest and fastest techniques to learn. You can even make your own active microbe starters for your compost. These microbes are known as Beneficial Indigenous Organisms (BIO) or Effective Microorganisms.

  1. Mix one part imported rice in the mixing bowl with two parts water and mix it vigorously with a fork. Purists use their hands, but you do not want to splash out of the bowl.

  2. Pour the contents of the mixing bowl into a strainer over a bucket. Make sure all of the rice water or rice wash ends up in the bucket and the rice in the strainer. You can lay out the rice to dry and cook it later, or cook it immediately. You can also wash it again. Asian cooks traditionally wash rice, sometimes two or three times.

  3. Loosely place the lid on the bucket. Do not seal it. Leave it in a dark area that's between 68 and 77 degrees F for five to seven days to culture the active microbes. The mixture should smell sour.

  4. Add 10 parts milk to the one part rice wash and let it sit for 14 days so it completely ferments. The rice wash collects and cultivates lots of microbes, some of which you do not want in compost, and the milk kills off everything but the lactobacillus. Strain the solids off the top of the bucket. The yellow liquid leftovers are purified lactobacillus serum.

  5. Dilute the lactobacillus serum in a 1:20 ratio with water and add it to your compost.


Do not use water treated with chlorine for any of this process. The water will kill the microbes and organisms you want to cultivate.