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Gardeners call it “black gold.” Compost is a natural soil conditioner created by the unexpected alchemy that turns trash into treasure. Work it into the soil, and it supports enriching microbial activity and beneficial insects that aid in soil aeration. Spread it on the surface, and the dark, decomposed organic matter will help suppress plant pathogens. Either way, compost improves soil structure by forming clumps that help retain moisture and resist erosion. Keeping a compost pile is an investment whose deposits deteriorate into portfolio assets that help your garden grow.
“Making compost is a slow digestive process,” explains Bruno Welsh, founder of Compost RVA. “The key ingredient is patience.” Welsh describes a community of beneficial microorganisms (from fungi and earthworms to pill bugs and bacteria) that live in and feed on organic matter, their tiny digestive tracts processing yard waste and kitchen scraps into a goldmine of soil conditioners.
Each ingredient in a compost pile hosts a different group of hungry microorganisms whose diversity yields an equally diverse blend of byproduct. “Brown” matter (dry, dead leaves, sawdust, and even shredded newspaper) contributes carbon to the mix. “Green matter” (grass clippings, kitchen scraps and coffee grounds) adds nitrogen.
“Good compost is dark and rich in color; it smells like earth.” —Bruno Welsh
“The carbon/nitrogen ratio is critical,” Welsh says. “In general, add more carbon than nitrogen for maximum efficiency.” A ratio of one part green to two parts brown is a good balance. Too much nitrogen will give the pile an unpleasant odor. Too much carbon will slow decomposition.
The living creatures that do the work in a compost pile also need oxygen and water to survive. Turn the pile with a pitchfork every few weeks, rotating material into the center to introduce air to the mix. And spray it with water until it feels like a wrung-out sponge — damp enough to support life, but not so wet that it inhibits airflow or reduces temperature.
Composting methods vary according to the type of container you use, the type of refuse you add and the microbes that thrive there. The most popular backyard method is an aerobic process that gets its name from the heat released as nitrogen and carbon react in the presence of oxygen. Called “hot” composting, the interior of the pile will sustain a temperature of 120 to 150 degrees for about a month.
For your compost pile, choose a shady spot close to a water source that measures at least 3 by 3 feet. Begin by spreading several inches of coarse brown material on the ground. Add a few inches of green stuff, topped by a thin layer of soil. Finish with a second layer of brown, and moisten the layers. Continue adding layers over time until you reach a compost-critical 27 cubic feet, enough mass to retain sufficient heat to kill off weed seeds or plant pathogens. (Bury kitchen scraps 10 inches into the pile when you add them, unless you want to run a backyard buffet for the critters in your neighborhood.) As you turn the pile you’ll begin to see signs of success: steam generated by the pile’s heat and colonies of earthworms threading through the crumbly black center.
“Good compost is dark and rich in color; it smells like earth and feels sticky and moist but not wet,” Welsh says. “When it doesn’t look like what it used to be, it’s finished.” Mix the finished compost into the soil and begin the cycle again, recycling nature’s precious plant nutrients by turning worthless refuse into a wealth of benefits for your garden.
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