How to Turn Food Scraps into Great Compost

Every Spring, I call my father, who is a master gardener, for advice on making compost. I don’t know if it is the water here in Los Angeles, or the air in Texas, but I never make good compost, despite following his instructions closely.

What Cynthia didn’t know was that food waste is particularly difficult to make quality compost with. It tends to rot without becoming that dark brown, rich material, with almost no smell, that gardeners value. Her father’s compost is probably a combination of green leaves, woody materials and biology from prior years of composting.

A couple of years ago, Mike McGrath in a TEDx talk called about this idea that banana peels, apple cores, left over salad and other food scraps can be turned into rich additives for a garden as The Big Lie of Composting.

Most people compost for Karma points. They want to stop throwing away their kitchen garbage, so they buy compost bins. The composters came with instructions that read,“Things you can include: grass clippings, leaves, kitchen waste, and even old newspapers.”

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Following the instructions, people fill compost bins with kitchen garbage, and wait for the food scraps to turn into something wonderful. While they are waiting, and feeling good about themselves, the garbage rots.Local Carbon Network (LCN)Membership helps you make great compost that sequesters 1 cubic yard of carbon..

Composting is an imitation of processes and patterns of nature, but in a more directed way, for faster results. Unlike humans, the natural world does not make big piles of trash, nor piles of uneaten food in the woods.

To understand how to compost well, think about the floor of a forest, littered with leaves and small plants, with animals eating the greens, walking and crushing the leaves. They leave saliva, urine, they defecate. There are insects and small animals burrowing through the organic matter. The material on the floor of a forest stays moderately moist, gets chopped up and turned. Except for the material on the very top surface, most is kept dark, insulated and creates an environment where the microscopic life decomposes the organic material.

In Nature

There are 7 types of life in healthy soil and well made compost, with broad biodiversity with thousands of species. The primary drivers for decomposition are the bacteria and archaea. As they reproduce and decompose/consume the material on the forest floor, they create warmth. That leaf litter often hits the 60 to 75 ֠ F range where the fungi grow — some of the fungi live on the dead woody material. The plants send sugars to their roots, causing multiple species of bacteria and fungi to grow with the help of the decomposed material, also known as organic material.

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In nature, this is a critical part of how plants are fed. The various types of microbes described above decompose by growing and creating acids and enzymes and carbon chains that include and bind the key elements the plants need (Nitrogen, Phosphorus, and Potassium (N-P-K), as well as Calcium, Sulfur, Magnesium, Iron, Boron, Manganese, Zinc, Copper, Molybdenum and Nickel.)

These elements are released in a plant available form when the bacteria and fungi are consumed by other microbes, or by the wee critters that are one step higher on the food chain, and eat the second trophic level.

In a Compost Bin

It would be difficult to replicate all of these steps that occur in nature, and a gardener is interested in fast, effective composting, which is bacteria based. Composting for gardens (and organic farms) is geared towards rapid decomposition of the material, and taking the temperature up to the range of 150 ֠+Fahrenheit, which kills microbes that could cause disease.

This can only be done with rapid bacterial growth. So, if you seek well made compost from your food scraps, you need to provide the right conditions for the bacteria to grow. Later, when the pile is cooling, you also need to add back those beneficial microbes, like fungi, which grow more slowly and die in the intense heat of a compost pile.

The fungi are a significant part of carbon sequestration by the soil.

In nature, the carbon and the nitrogen are balanced, with greens, woody materials and manures. Time, moisture, occasional movement or stirring of the material and broad biodiversity are needed.

In the compost bin, most of that food is heavy on nitrogen, so woody materials (carbon) is required in equal amounts to the food. This woody material can include small pieces of cardboard, sawdust, wood chips, dried leaves, paper towels and shredded newspaper) Green leaves and lawn cuttings are great, but also add to the nitrogen and again, need an equal amount of carbon to become compost.

Additionally, the pile needs to have the right environment for the bacteria, which biochar creates, in order to thrive, reproduce and bring the compost to the right temperature.

Biochar, under a microscope looks a bit like a coral reef. Woody material has been charred, under exacting conditions, and becomes pure, inert carbon, with homes for a variety of microscopic critters of various sizes. It also holds pockets of air and is hydrophilic, even pulling water from the air.

Want Karma points? In addition to helping waste turn to compost, Biochar is an amazing soil conditioner, and will continue to help your soil for more than 1,000 years. First discovered in the Amazon and dubbed Terra preta (black soil in Portuguese), it improves soil fertility, reduces irrigation needs and represents agricultural waste that is returned to the ground, in carbon sequestration.

For the gardener, biochar also stimulates the bacterial activity — raising the temperature of the compost pile to that critical range, while the bacteria are breaking down the food scraps into that highly desirable, good compost.

How to Make Good Compost from Food Scraps

First watch Mike McGrath’s very amusing 17 minute TEDx,Everything Think You Know About Composing is Wrong.

Fill your compost bin with food scraps, equal amounts of woody material and about a cup of raw biochar for every pound or so of food scraps.

Join the Local Carbon Network, which is rolling out nationally. Membership includes wood material, biochar and a biological finisher with the rest of the Soil Food Web on a monthly basis.

We have found that the Joya Composter, which is insulated, easy to turn, and is weather and animal resistant, is the best composter on the market. The insulation is insufficient without biochar. But the biochar alone may not be sufficient if your compost pile is small.

The Joya Composter has 2 bins, so you can be composting and using finished compost in your garden at the same time.

Learn more about the Local Carbon Network or here.

See also:

Soil Building for a Victory Garden

Biochar, a Soil Biology Perspective

Biology from SymSoil , a leader in development of biological soil amendments for agriculture that restores the microbes that provide the right food to the plant roots, improving plant health, and making food more nutrient dense and flavorful, the way nature intended.

SymSoil has products and services for growers using regenerative agriculture methodologies which improve profitability. Its flagship product, SymSoil® RC (Robust Compost) is a complex community of soil microbes, which includes in excess of 1,000 species, covering broad biodiversity of bacteria, fungi, amoebae, and other protozoa, beneficial nematodes and microarthropods. SymSoil was named one of 2019’s AgTech Companies to Watch. Accredited Investors can learn more about SymSoil as an impact investment here.

All Power Labs of Berkeley started the Local Carbon Network in 2018 and provides the high temperature biochar used by LCN. APL raised nearly $50,000 selling bags of biochar in an effort to move carbon from “sky-to-soil” through this composting and planting process in Berkeley. The network is pushing for involvement throughout the San Francisco Bay Area, and has sequestered about 50,000 kilograms of CO2 so far, according to the company.

The ultimate goal to have Local Carbon Networks around the world, allowing individuals to capture and sequester carbon for use in community and personal gardens.

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