Rainbow compost plant in jeopardy, but final product still intriguing

Plans to build a compost plant on Rainbow Open Space took a step back last week as Boulder County Commissioners expressed concerns with the location and asked for more creative solutions to deal with organic waste.

"If we do a site, for me, not on Open Space lands, that's not what Open Space lands are for, no biosolids from wastewater treatment plants, we should be imaginative and maybe use a smaller scale and include the public," said Commissioner Matt Jones. Commissioners Claire Levy and Marta Lochamin also expressed interest in alternative ideas.

Commissioners accepted a Public Works staff recommendation to withdraw the application for a special use permit at the former tree nursery on Highway 287. The procedural move was necessary to allow an open discussion between commissioners, staff, and the public on the proposed facility and additional solutions for organic waste which is currently thrown away or trucked out of town.

"If it goes to a landfill it causes climate problems. It has methane gas that comes out of the landfill and we could put that compost to good use to help with soil health which would help sequester carbon," Jones said.

Generating compost for agricultural use was a stated goal of the original plans for the compost facility. But several area farmers say they weren't asked about their need for compost and don't know anyone who was. Turns out, agricultural use of compost is complicated, even though it holds promise.

"I think compost is incredibly vital in reducing our waste stream," said Michael Moss who runs Kilt Farms near Niwot. "Utilizing compost for long term sustainability for me makes total sense." He leases land from Boulder County and, like several local farmers, said he uses compost in a limited, targeted way. He thinks a local source would be helpful to farmers, potentially reducing the cost, one of the biggest barriers to widespread use.

There are a lot of factors that go into whether a farmer uses compost. Wyatt Barnes owns Red Wagon Farm in Boulder County, a small, organic vegetable farm that sells directly to individuals and at local farmers markets. "Compost has its place, but it's pretty limited," Barnes said. "It has massive obstacles in material handling, moving it, applying it effectively and we just don't need that much of it and there are suppliers out there that do a good job."

Barnes leases land from the county. Some of the soil was in rough shape at first, so he bought compost to increase fertility. It helped. Now he makes his own on the farm at a fraction of the cost.

Once Barnes improves his soil, he keeps it full of nutrients by planting cover crops that are not harvested as food, but hold the soil in place and return nitrogen and some organic matter to the ground. "That works pretty well without having to add a bunch of other stuff," Barnes said.

Farmers are constantly balancing nutrients in their soil. Compost is one component of that. "Compost has generally beneficial bacteria and broken down plant material. Growing plants benefit from this and do well, especially in the short term. Long term, the plants don't use many of the minerals that quickly and the compost added has way too much of some nutrients. Some of the weeds react to the overabundance of some of these nutrients and grow like crazy," Barnes said. "You have to mess with it on your own soil and learn."

Compost increases soil organic matter, or carbon, and helps create an ecosystem that supports plant growth, according to Mark Easter, a research associate at the Natural Resource Ecology Lab at Colorado State University.

"The more organic matter you have, the more rich the microbial community is going to be. And the microbes in the soil, the soil ecosystem, help make those nutrients available to the plant more efficiently," said Easter.

"There is really exciting research in the role microbes play in maintaining a healthy soil that is productive for the farmers and produces healthy, nutritious food," he said. "Applying a well-made compost to the soil can induce what people are calling an ecosystem shift in soil to diversify the microbial community and that plays a big role in carbon sequestration."

But tilling soil makes it hard to keep carbon in the ground. "It goes back in the air," Barnes said. He tills as little as possible, but says it's necessary for his vegetable crops.

Easter said the amount of carbon that stays in the soil varies from farm to farm and state to state. It accumulates over time. Easter added that some corn farms in the Midwest are able to avoid tilling after investing 10-15 years building healthy soil. The wetter climate helps.

Here in dry Colorado, farmer Paul Schlagel grows corn and is involved in a CSU study on compost and soil health. "It's a challenge to me to still have solid evidence that we're doing the right thing even after four years," Schlagel said. "There is no doubt that the yield is higher. But are we getting our return on our investment? We don't know that yet. We have our doubts, but we're going to keep doing it."

It's possible that a county-owned compost facility could subsidize the cost of compost for farmers. But they also need equipment to spread it, costing around $100,000, according to Schlagel.

Easter said improving soil health means less fertilizer over time, reducing that cost. Additionally, research is showing higher yields and more resilient crops.

The quality of compost is another factor in how widely it's used. That depends on what goes into it and how well it's made. Contamination is a problem for the industry, particularly plastic, glass and the little stickers on grocery produce that don't break down during composting.

Invisible particles are also a concern, especially for compost made from biosolids, otherwise known as treated human waste. Heat from making compost can kill pathogens, but some things in biosolids don't break down, including persistent chemicals. Biosolids have been considered for a county compost facility. Organic growers cannot accept compost from biosolids.

Demand for compost is growing in landscaping and agriculture is gaining more attention. Using compost to sequester carbon and build soil health is a long game. Easter compares it to the early days of recycling. He said we've gotten better at that and he expects the same for composting.