From Scraps to Soil: Concluding a Compost Report

Where Our Food Scraps Go

1Every week, many families in Riverton put apple cores, carrot peels, and coffee grounds into a green bin by the curb. A truck carries the scraps to the town compost site at the edge of town. There, the scraps slowly turn into something useful. A compost site changes food and yard waste into rich soil, and it takes the right mix of materials, careful workers, and time.

2The first step is making a good mix. Workers put food scraps and fresh grass clippings, which are called greens, into long piles. Then they add browns, such as dry leaves and wood chips. Greens and browns work best together. A pile with only greens can get wet and smelly, while a pile with only browns breaks down very slowly.

3Next, tiny living things do most of the work. Bacteria and fungi are too small to see without a microscope, but millions of them live in every pile. They feed on the scraps and break them into smaller and smaller pieces. As they work, the middle of the pile gets warm. On a cold morning, workers can sometimes see steam rising from the top of a pile.

4Workers help these tiny helpers by giving them air and water. Every so often, a worker uses a large machine to turn the piles over. Turning mixes in fresh air, which the bacteria and fungi need. Workers also check that each pile stays damp, like a sponge that has been squeezed out. If a pile gets too dry, they spray it with water.

5After several months, the scraps no longer look like peels or leaves. The finished compost is dark and crumbly, and it smells like a forest floor. The town gives some of it to community gardens and spreads the rest in parks and school flower beds. Compost helps soil hold water, and it gives plants nutrients they need to grow.