Soil Science: Down and Gritty in the Dirt

Think all that organic waste you toss in the trash decomposes in the landfill? Think again. Composting it is better for the planet, as bacteria and fungi break down the nutrients, energy, and matter making it available to create new life through nutrient rich soil. Watch how residents, businesses and non-profits utilize the soil cycle to make money, food, and community.

DURHAM - This is a story about soil, and what you could call the soil cycle. It’s a story about the cycle of life, death, and decay that produces new soil. And in turn, that new soil helps produce new life.

Let’s start our story in the Durham backyard of Natalie Ross and John Jack. They are building several flowerbeds and a garden, hauling compost from a pile in their driveway into sections of their backyard. Compost, by the way, is decayed organic material that’s been added to soil. About ten months ago, the compost they are now raking in their backyard looked totally different. It was organic waste, similar to what is sitting in a pail on their front porch. The couple has signed up to be part of a home pickup composting service.

Natalie shows me what’s in the pail. It is pretty disgusting.

“There is rice, tea bags, a rotten potato, what’s left of a sandwich, the bone from the steak we had last night,” Ross says, moving a gloved hand around the contents of the pail. “There are even coffee grounds. I’m amazed at how many coffee grounds get tossed in the landfill. Basically, if it comes from life, it can be composted.”

You would think organic waste that is hauled to a landfill decays. It does, but because landfill waste is so tightly compacted, it doesn’t decay efficiently and so it creates methane gas, which contributes to global warming. In addition, what does decay and turns into nutrient rich soil is lost forever because it sits trapped in a landfill.

The U.S. Environmental Protection Agency estimates that about 30% of household waste is organic and can be composted.

Brooks Contractor wants to do something about that.

“Composting is by far the quickest, safest way to get organic material into the soil, and organic matter is the key to all of these soil processes that actually create soil,” Amy Brooks yells to me, as a huge tractor trailer hauling food waste drives by.

Amy and I are standing in the middle of the 30-acre site in Goldston, NC that is the home of Brooks Contractor, one of North Carolina’s giant composting companies.

Brooks Contractor collects almost 60,000 tons of compost from restaurants, school cafeterias, grocery stores and other companies every year. It produces about 40,000 tons of compost which it sells to landscapers and garden supply stores.

Amy reaches her hand into a pile of moist, dark and crumbly soil and pulls out a handful to show me.

“This is excellent compost,” she says as she points to some light brown flecks in the handful. “Those brown flecks are bits of eggshell, which is an excellent lime source for soil, a slow release lime source. There is a ton of microbiology in this dirt, so what is in my hand is very much alive.”

Compost starts as a mix of used cooking oil, organic waste such as vegetable peels, fruits and vegetables that have spoiled, leftovers from dinner plates and even manure, along with hay and feed from the state fair grounds. Even Amy admits it is a pretty disgusting combination. Brooks Contracting collects it all, mixes it together, and then spread it out into long wind rows. Those rows stretch up to 200 feet long, as far as the eye can see.  

The materials sit in various mixing piles as well as in the wind rows for ten months. The temperatures in the pile reach 130 degrees, hot enough to break down bone as well as kill any harmful bacteria. Giant machines turn the piles every few days because the microorganisms that break down the waste need air and water to do their work.

The piles are carefully managed, not only to keep the composting process going, but also to reduce odors. A compost pile that is working efficiently does not smell badly.

After about ten months, when the compost is ready, it is sifted to remove objects larger than a ½ inch. Items that can be composted are returned to the wind rows. Objects that won’t decay are disposed of. The compost is then mixed with topsoil, or clay, or other mixes depending on what the compost is used for. It is then delivered to customers.

One of those customers is Cullen Whitley, who manages the Goodwill Community Foundations Community Farm. Soil tests show the farm, which sits on white clay soil, should not be very productive. The soil is not only very acidic, it also has a low cation exchange ratio, which means the soil will not absorb certain nutrients. 

However as you look around the three-acre site, there is something growing in almost every inch of land. Whitley brought in truckloads of compost, which improved the soil so much, that almost anything could grow in it.

Whitley also checks the soil almost every month, adding lime to improve the PH along with other minerals as needed. He credits soil science with the farm’s amazing productivity, which is donated to local food banks. He does not use fertilizer. 

“To have good shoots, you need good roots,” Whitley says, while pulling a huge carrot out of the ground. “This is a Bugs Bunny, and to have good roots like this you need good soil. And to have good soil you need to do certain things; you need to check the PH, you need to have friable material which makes the soil workable, and compost keeps the soil fluffy and it will do your fertilizing for you.”

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