Prepare Your Garden Soil:
Making Compost

The Carbon Problem

Too much carbon in the air is bringing us increasingly extreme weather and driving the rapid breakdown of our climate patterns.

Too little carbon in our soils contributes to widespread flooding and drought and reduces the fertility and stability of food-producing land. So, moving carbon from the air to the soil is one of the winningest ‘Win-Wins’ of all time.

We’ve made short presentations (YouTubes?) on four relatively simple ways that gardeners and small scale farmers can help to relocate this carbon to where it is valuable. These are:

• Making compost
• Making Hugel beds
• Making biochar and
  
• Growing edible cover crops

We’ll start with compost, the best known of the four.

Composting uses biology to provide us with two important services;

• Safely disposing of organic wastes and
• Increasing the organic matter content of our garden and farm soils.

About 1/2 of everything that gets thrown away in the US could be composted. It costs an average of $50 a ton to dispose of this organic waste in a landfill (formerly and more accurately called a “dump”). Organic wastes in landfills generate methane gas. Methane is roughly 30 times more potent than Carbon dioxide in trapping heat and altering our climates.

Especially for the home gardener, it is far better to make compost with our organic wastes and to use the compost to improve our soil.

Compost improves soil in several different ways.

• Compost inoculates the soil with beneficial bacteria and fungi and reduces damage from plant diseases.
• It moderates the pH (or acidity) of the soil
• It improves aeration and texture of the soil
• By increasing the Cation Exchange Capacity, compost allows soil to hold more nutrients in forms that are easily used by plants. This slow and steady supply of plant nutrients is especially important in sandy and low fertility soils.
• Compost increases the water holding capacity of the soil. This point is especially important. Most cultivated soils have less than 3% organic matter; about one-half of their original level. Increasing organic matter back to 6%, with compost (and Hugel beds, biochar, and cover crops) will enable it to hold much more water. Roughly 140 gallons more for a typical 100 square foot garden bed, or 60,000 gallons per acre. This additional water reserve in the soil can reduce the threat of both flooding and droughts.

That is a lot of benefits; so how do you make compost? There are a lot of different approaches, but one of the best ways to make compost is to alternate layers of high carbon material with thin layers of high nitrogen material. High carbon materials like, straw, tree leaves, cornstalks, and wood chips are often referred to as “browns. Manure, fresh grass clippings, bean, and pea plants are richer sources of nitrogen, and are called “greens”.

It is best to avoid pet feces (like used kitty litter) because they can spread disease. Also, avoid meat scraps and fats as they can attract raccoons and other animals.

Keep alternating brown and green layers until you have a pile with a volume of at least a cubic yard or cubic meter (about 3 feet by 3 feet by 3 feet). This can be done as an open pile or more neatly stacked, like this compost pile in Kenya contained with cassava stalks.

A ring of fencing or a box made of scrap wood are other ways to contain a compost pile.

Turning your compost pile occasionally speeds up the decomposition process. Open piles are easier to turn than enclosed piles. Really big piles can be turned with a rototiller to save your back.

Lets quickly run through the process:

Making a compost bin with 4 pallets or skids, works well where space is limited or tidiness is important.

If possible, gather all the materials for making your pile before you begin. The greater the diversity of materials composted, the greater the diversity of beneficial bacteria and fungi in the compost. This diversity makes the compost more valuable in the garden soil.

We are starting with a layer of brush for better drainage. Then, we begin laying in waterweeds (the Leaf for Life garden is adjacent to a lake in north-central Florida). Next, we add garden weeds and garden plants that are no longer producing. The soil clinging to the roots brings beneficial bacteria to the compost pile. Tree leaves that have been soaked beforehand are then added. Next come layers of horse manure, more waterweeds, a little garden soil, kitchen scraps, and old hay. Some seaweed ensures a good supply of key trace minerals.

Add the layers loosely, to allow air in. Aerobic bacteria need oxygen to thrive. Ideally, the pile is kept about as moist as a wrung-out sponge. If the pile is too wet and doesn't contain enough air, the beneficial aerobic bacteria are replaced with anaerobic bacteria that create foul smells and much less valuable compost for plant growth.

When the pile begins spilling out the front, the fourth pallet is wired on. The rest of the pile has to be tossed in over the top.

If dry weather is expected, the top of the pile can be indented a little to help catch water. During wet weather, mounding the top of the pile will help it drain excess water.

After 3 or 4 days thermophilic (or heat-loving) bacteria will begin to rapidly decompose the organic matter causing the center of the pile to reach a temperature of 130-160 F (54-71 C). 140 F is a high enough temperature to kill most weed seeds and pathogens. Temperatures over 160 F (or 70 C) will reduce the quality of the compost.

You can check the temperature with a probe thermometer or by pushing a piece of rebar into the center. After an hour or so in the pile, it should come out hot to the touch. (show thermometer and rebar)

When the compost is finished it should have an earthy smell and it should be difficult to identify any of the initial ingredients.

Sifting the compost removes larger pieces, that can be sent back for further composting. It also makes a uniform and easy-to-handle material to use in your garden. Some of the finished compost becomes carbon-rich humus resists further decay. Humus can hold soil particles together, absorb 6 times its weight in water, and keep carbon out of the air for many years.

We usually try to spread 1-2 inches of finished compost on our vegetable beds each year.

If you don’t plan to put the compost in your garden right away, covering it will help hold in nutrients and prevent it from leaching or washing away.

Variations

There are several other variations on making and using compost that have enthusiastic practitioners.

Vermicomposting, or using worms to break down organic material, is a more specialized method that creates extremely high-quality compost.

Bokashi is an anaerobically fermented compost based on rice hulls, It was developed in Japan.

Actively aerated compost tea is a somewhat complicated process that uses special equipment to make a potent sprayable compost.

Instructions for trying all of these can be found on the Internet.

Compost Is Your Friend

Making compost turns waste into a valuable product. Composting can become a key piece in moving from wasteful economies towards more sustainable circular economies. It is an important discipline for integrating humans into natural ecosystems.

So, especially if you are a gardener, compost is your friend.

Thanks for watching.

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