SHERIDAN — The signs of fall rest on the ground all around Sheridan. Millions of leaves clutter yards, fill gutters and collect on street curbs to indicate the oncoming winter. The process is all part of the seasonal cycle, but those leaves become part of another cycle, too.

According to Shawn Stevens, city of Sheridan landfill supervisor, leaves play an important role in composting and, therefore, contributing to the growth of new plants in the community. Each fall, leaves are delivered to the landfill and placed into a green waste pile that is then mixed with grass in the composting yard. The leaves provide both nitrogen and carbon to fuel the composting process.

The city accepted about 8.5 million pounds — 4,250 tons — of green waste in fiscal year 2017, which lasted from July 2016 through June 2017; Stevens said that’s about average for the city.

The city uses an Ag Bag system, which is an in-vessel system that involves putting compostable material into large plastic bags then controlling the temperatures with the use of internal pipes and fans. The landfill staff also monitors temperatures using sensors to meet regulatory requirements. In doing so, they ensure that weed seed and harmful pathogens are destroyed before the compost is distributed.

The entire process can take a minimum of two months, but can stretch into six months based on factors such as mixture, ambient temperatures and curing time, according to Stevens.

All of that green waste is anything but waste, though. 

“The compost that the landfill sells can be used for just about anything that has to do with soil enhancement including new and existing lawns, general landscaping, planting beds, gardens and landscape plant mulching,” Stevens said. 

While Stevens said the compost yard stays busy throughout the year, demand for the compost is highest in the spring and fall for gardening. Residents and commercial businesses can purchase compost from the city for $30.05 per ton.

The green waste collected accounts for about 20 percent of the landfill’s waste stream, and the composting process saves a significant amount of space in the landfill. The cycle that starts with leaves falling and ends with fresh compost keeps the city’s beautification process an ongoing one.

According to the Environmental Protection Agency, compost has a number of benefits. It enriches soil, helping to retain moisture and suppress plant diseases and pests.Compost also reduces the need for chemical fertilizers and encourages the production of beneficial bacteria and fungi that break down organic matter to create humus, a rich nutrient-filled material.

Jessica Bohnsack, store manager at Landon’s Greenhouse and Nursery, said compost helps nourish the soil with micronutrients plant roots need to grow and also helps loosen and aerate clay soil or amend sandy soil.

Bohnsack didn’t recommend compost for potted plants, but advised that it can be added to other plants anytime during the spring, summer or fall.

She advised that for individual plantings, such as trees and shrubs, gardeners amend soil so it’s one-third compost and two-thirds native soil. For garden beds, she recommended adding a couple of inches of compost to the top of the bed and working it into the soil in the spring. Or, in the fall, she said, let it sit through the winter and let Mother Nature work it down into the soil for you.