The Simple Science of Composting


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Many of us think of composting as a way to control household waste. And while minimizing waste is one significant benefit of composting, gardeners can delight in another perk: Creating nutrient-rich food for plants and soil.

Don’t think compost can really make a difference for low-quality soil? Consider the story of Ken Singh, owner and operator of Singh Farms in Scottsdale, Ariz. When Singh first arrived on his plot in 2002, the soil was typical of Arizona’s deserts: hard, dry and clay-like. He calls the soil “the worst dirt I’ve ever seen.”

To solve the problem, Singh started composting on his farm in 2003 and began replenishing the soils depleted nutrients. Today, the plot is unrecognizable. Pale, sandy dirt is replaced with dark and healthy soil – so soft and moist it literally squishes beneath your feet. Lush forest canopy shades rows of vegetables, fruits and flowers – a stark contrast to the scorched earth surrounding the farm in Arizona’s Valley of the Sun.

So, how did Singh use composting to achieve such stunning results? Earth911 went on a tour of Singh Farms to get the low-down on some of his most successful composting methods and compiled this list of six things you should be doing to get the best quality compost for your home garden.

1. Do the math

Some folks have the notion that composting is only for “tree-hugging hippies,” but there’s actually a great deal of science and – gasp! – math involved in the process.

“What I work on is a carbon-nitrogen ratio, because that’s what makes energy,” Singh says. “If you don’t have that, you’re not cooking compost.”

Basically, the carbon-nitrogen, or C/N, ratio quantifies the amount of green and brown waste in your compost pile. If your compost mix is too low in nitrogen, it will not heat up and your scraps won’t decompose. If your mix has too much nitrogen, it may become too hot, killing compost microorganisms.

Learn More: Cheat Sheet: Composting

While the optimum ratio for your pile will vary based on soil composition, the usual recommended range for C/N ratios is about 30/1, according to Cornell University’s Waste Management Institute. The C/N ratio will decrease during the composting process as carbon is converted into CO2. A 10/1 ratio is typical of finished compost.

Not sure how to gauge the carbon and nitrogen content of your compostable waste? Check out Cornell University’s Waste Management Institute for tips on estimating carbon content.

NEXT: More need-to-know composting tips

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Mary Mazzoni


  1. in Ohio, did it in 17 days with 1/4″ hardware cloth wrapped in a 3′ diameter circle. in the desert you will need to steel food scraps from Robecks to get the moisture up and keep it covered to keep the moisture in.

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