San José, Costa Rica, since 1956

Three-Step Composting Helps Turn Red Clay to Fertile Soil

Readers have written to me with the same question: What can I do about my hard, red clay soil? Nothing seems to grow for me. Help!

Fortunately, there’s a natural solution to change that red clay into fertile garden soil.

It’s called composting, and it’s an important aspect of tropical soil building.

Most kitchen waste, dried leaves, grass cuttings, weeds from the garden and livestock manure can be returned to a compost pile to make rich, fertile soil.

Applying compost to your garden increases its fertility and productivity each year.

When you recycle your organic waste at home, you also help reduce problems of public disposal.

Every day in Costa Rica, hundreds of tons of organic waste are disposed of in landfills without being returned to the soil. It is estimated that 40% of landfill waste is organic matter, which could be utilized as fertilizer for agriculture.

Ecologically sound gardens demonstrate a viable alternative to the dilemma of waste disposal, and compost can save you money with a bonus of free fertilizer and inexpensive homegrown food for your family.

Soil contains many types of beneficial microorganisms, such as bacteria and fungi, which function to decompose organic matter into nutrients to feed their populations.

Unseen to your eyes, they grow, reproduce and die in life cycles that are measured in hours. In the process, organic material is turned into humus, which is the perfect plant food.

You can create humus with this same process, which usually occurs in the first few centimeters of topsoil, by composting. By introducing the proper microorganisms into a large mass of organic material while providing optimal conditions for them to grow, it is possible to create rich humus in large quantities for your garden’s soil.

Composting is a very flexible process in which a wide variety of organic waste can be converted into rich humus. A compost pile where organic waste is recycled into natural fertilizer can be created near or in the garden.

Each pile may have a unique combination, but here is a general formula for making good compost.

Step 1

Most gardeners layer a compost pile over a period of several weeks. First, add a layer of dry leaves or finely chopped banana stalks or other high-fiber material on the ground. A pile can be made in a circular fashion about two meters wide and piled to a meter high, or in rectangles one meter wide, three meters long and a meter high.

Next, add a layer of manure, kitchen scraps and grass clippings or weeds from garden cleanup. Then add soil and a small bit of compost from a previous pile. This provides the necessary microbes and can be used to cover the organic material.

You can also add EM, or effective micro-organisms, which is a liquid culture of safe, beneficial microbes that decompose compost rapidly and efficiently. It’s made by the students of EARTHUniversity in the Caribbeanslope town of Guácimo.You can contact their office at 2760-0069.

When organic material is cut into smaller pieces, microbes have more surface area to grow on and decompose the organic waste.

Chopping through the pile with an old machete is a simple and effective method.

Once your pile has reached one meter high, start a new pile; if you keep adding new waste to an old pile, it will never become rich, odorless compost soil. An average garden should have at least three compost piles in different stages of decomposition, for a steady supply of compost each month.

Step 2

Good compost can be made in two months if the pile is turned every 15 days to incorporate air into the organic mass.

Beneficial aerobic bacteria and fungi need air to carry on their metabolic life functions.

The more air they receive, the faster they grow and, therefore, the faster the compost decomposes. Their growth is so rapid that the pile will actually heat up – a good sign that your compost is cooking well.

Step 3

Water is also essential for microbes to grow well; however, too much water can slow their growth. The pile should be moist, but not soaked. For this reason, it’s important to cover the compost pile to protect it from heavy tropical rains. Since these microbes function best at high temperatures, it’s best to situate compost piles in sunny areas and, if possible, cover them with black plastic. This also helps to prevent insects from breeding in the pile.

When the compost is finished, you can also add small amounts of ashes and limestone.

Use approximately one cup of each powdered material with one wheelbarrow load of soil and compost.

Try to save 10% of your finished compost to use for new piles. You can add your finished compost to garden beds, landscaping or tree plantings by forking it into the top 30 centimeters of soil.


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