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Acres of barren Boulder soil are headed to rehab (and that might just help fight climate change)

Project to make depleted open space owned by the city healthy again could be a blueprint for carbon capture and land management

Marcus McCauley's farm land borders 120 acres of city of Boulder agricultural land where he is piloting a soil restoration project the city hopes can help it meet its climate goals. (Nina Riggio, Special to The Colorado Sun)
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Walking toward the western edge of his farm, Marcus McCauley pauses to roll a cigarette, lighting up before jumping the fence dividing his property west of Longmont from the neighboring farm. A coyote walks across the far end of the 120 acres, traversing a patchwork landscape of exposed dirt and low greenery, pocked with prairie dog holes.

“A lot of the green you see is bindweed,” McCauley says, pointing away from his farm. “You have to look a little closer to get the full story.”

In 2016, a fierce windstorm blew the topsoil — the normally fertile ground where food is grown — off the neighboring property and onto McCauley’s farm, setting back production on his land by weeks and driving away his honey bees. The dust came from one of at least 1,000 acres of land owned by the City of Boulder that is in such poor condition that it cannot be leased to farmers because nothing will grow there.

“As a neighbor, I’ve been hurt by the way they’re taking care of their land, and so have other farmers around here,” McCauley says. “You drive around, and the worst land is open space.”

McCauley is working to restore soil quality on the barren farm and in the process help Boulder achieve its climate goals. And if his pilot project goes well, the city hopes to ramp up the scale of the restoration program.

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Environmental planners at the city estimate that well-managed soil has the potential to suck out of the air up to 20 tons of carbon dioxide per acre per year. If Boulder restored 1,000 of the 15,000 agricultural acres it owns, environmental planners think they could sequester 20,000 tons of CO2 — four times what the city has achieved through emissions reduction.

“A growing number of acres of ours have actually become unleasable because of a combination of factors, which include past management factors, climate change and prairie dogs,” says Brett KenCairn, senior environmental planner for Boulder. He’s part of a team working to address ailing soils on some of the city’s 45,000 acres of open space. “Right now, we know at least 1,000 acres of our lands are unleasable. It’s probably more. And those impacts are happening on lands that are currently leased, so they’re making some of our leased land much less productive.”

Brett KenCairn is Boulder’s senior policy adviser in climate sustainability and resilience. He was hired in 2013 to write the next iteration of Boulder’s climate plan, back when it seemed climate change could be stopped. (Nina Riggio, Special to The Colorado Sun)

Worse, the unleased land puts water rights associated with the farms in danger. Unused water can result in forfeiture of the right to it in future years, he said. Looking toward a drier future, Boulder is concerned. 

As Colorado begins to feel the effects of climate change, desertification has begun to alter the landscape, and KenCairn says the interplay of threats can make soil rehabilitation more complicated. Climate change, for example, makes land harder to recover after its vegetation is mowed down by prairie dogs.

“That was the case with the land next to Marcus. The wind event on our land actually damaged Marcus’ land, so there was an interest he had in seeing something done about that,” KenCairn says. “When we started to recognize some of the things he’d done in recovering his own land and started thinking about some of the things we could do with carbon sequestration and soil regeneration, we just thought that would be the perfect site.”

Boulder now employs McCauley as a contractor, hoping his regenerative practices will create a plot of land healthier than it has been in decades.  The city spent $9,867 on the project last year, including management, labor, equipment and materials, and has budgeted $17,000 for this year.

“It’s the flagship for a larger program. We’re now in active discussions for developing a much larger soil-regeneration, carbon-sequestration initiative that could potentially be applied on several thousand acres,” KenCairn says. “It’s about our contributions to the larger global carbon bank, it’s about preparing ourselves to be more resilient to climate change locally and it’s about being able to feed and nourish our populations more adequately.”

Dorper sheep, a South African cross, is well-suited for arid climates like Colorado, but also plays a big role in Marcus McCauley’s agro-ecology. “We started with mixed vegetables, and I learned a lot,” McCauley said. “But I needed to see what the land needed. We knew we needed to focus on pasture regeneration and animals.” (Nina Riggio, Special to The Colorado Sun)

How the sheep and chickens help

McCauley started working the plot in 2018 and says it reminded him of what his grandparents went through during the Dust Bowl in Oklahoma. He described the land as a moonscape of jagged rock. McCauley has been here before. His 39-acre McCauley Family Farm was in a similar state when he bought it in 2012. Over the past seven years, McCauley has worked to create a profitable farm and restore the land where he raises sheep and chickens for meat and eggs sold at farmers markets and through a community supported agriculture program.

“If you zoom out and ask what this land wants to be, we try to farm with that,” McCauley says. “It wants to be a savanna, a short grass prairie interspersed with some trees. So how do you eat from that?” 

McCauley sees his small farm, where he also grows peppers for his homemade Picaflor hot sauce, as a logical departure from the hyper-specialization of industrial agriculture in the United States, where farmers grow a single crop at the expense of their soil and pay to import nutrients onto the farm, while feedlots pay to remove animal waste that would be healthy in smaller doses. 

McCauley’s farm has pasture land interspersed with orchards. In the pasture, he has sheep grazing in rotating patterns. After a few days, he lets his chickens loose on the same sections, where they eat the insects that feed on the sheep’s dung. The fruit trees serve as a windbreak and provide shade for the animals, in addition to helping feed the chickens. The chickens, in turn, eat the codling moths, which can destroy an apple harvest. The chickens also roam his pepper fields, fertilizing as they fatten for market.

“We’re closing that system,” he says. “It’s the fruition of this vision of ecological farming that’s functional and productive.”

MORE: Read more environmental coverage from The Colorado Sun.

KenCairn sees an opportunity for Boulder’s climate goals in the restoration process. He was hired in 2013 as part of a team working to create and implement a plan to keep Boulder in line with global climate goals. 

“Our plan — like everybody else’s, I think — was largely focused on emissions reduction,” KenCairn says.

At the time, the Intergovernmental Panel on Climate Change recommended an 80 percent emissions reduction by 2050. In October, however, the panel released the alarming 1.5-degree report, which concluded the Earth is on track to warm by 1.5 degrees Celsius between 2030 and 2052, the threshold that the Paris Agreement was created to avoid, and warned of catastrophic environmental and economic consequences. If aggressive climate mitigation is not undertaken immediately, the coming disaster will scale proportionally, the panel said.

“The IPCC report comes out saying, essentially, not only are we not on track to achieve that goal, but emissions reduction alone will not be enough to stabilize climate,” KenCairn says. “We have to implement really aggressive programs to take carbon back out of the atmosphere.”

While some climate scientists propose geoengineering — increasing the reflectivity of clouds to reflect more of the sun’s heat into space, for example — KenCairn prefers working with the tools the planet has provided. Commonly referred to as natural climate stabilization, scientists hope to harness the carbon-recycling parts of the planet to suck greenhouse gasses out of the atmosphere. Reforestation is the classic example, but KenCairn says grasslands have big potential as well.

“In the right conditions, soil can take up a huge amount of carbon. Those conditions include that it needs sun and it needs moisture,” KenCairn says. “As we started to look at what the climate plan needed to be — to be in alignment with the new climate science — we recognized that we had to add an approach to participate in the sequestration side, not just the emissions-reduction side.”

Marcus McCauley has spent the last three years working “experimental plots” on his own farm and on Boulder open space to test the best ways to put carbon back into the soil. (Nina Riggio, Special to The Colorado Sun)

Getting the water to soak in

Keeping water in the desertifying land in northern Colorado can be a challenge. Instead of sinking into the ground through the breaks created by the roots of plant life, the water skates along the surface, sometimes flooding nearby areas.

Before McCauley can start growing food on the city land, he needs to get water into the ground. Since his project is, in many ways, a test, McCauley is experimenting with different methods, including flood irrigating and keyline plowing, a process that diverts water along slight troughs in the hillside, allowing it to better absorb into the soil.

“Water wants to flow down to the valley,” McCauley says. “We’re taking technology and human ingenuity and putting a line into the ground and saying stop at a 90-degree angle to that flow, taking it out of the valley, onto the ridge so the water will spread, slow down and infiltrate. That’s a way of trying to get that ecology back as quick as we can. Eventually, we won’t have to do that.”

Marcus McCauley manually floods the Boulder open space land to “test different practices for carbon sequestration to see what moves the needle most.” He floods one side of the property but not the other to compare and contrast. (Nina Riggio, Special to The Colorado Sun)

Next comes establishing plant life. McCauley hopes to kickstart growth with hardy annuals, like Sudan grass and radishes, that can thrive as they open the lean soil. He believes they can prepare the soil for more nourishing perennial plants that require microbial life in the soil and live for many years.

If McCauley can reestablish a diverse range of plant life, he can turn 120 fallow acres into a pump, sucking carbon out of the air and feeding it to microbial life in the ground. And over time, healthy grasslands pump a lot of carbon, as much as 3 to 5 tons per acre per year, KenCairn says. Each ton of carbon is equal to almost 4 tons of carbon dioxide.

Boulder aims to cut emissions to 400,000 tons per year by 2030, more than a third of the city’s current 1.5 million tons. KenCairn says that city could potentially sequester 20,000 tons of CO2 on 1,000 acres — 5 percent of its 2030 goal.

“If we could do 5,000 acres, we’re five times that. You start to see the numbers get really significant,” KenCairn says. “And we’re adding a huge number of benefits around resilience, water holding and microclimate.”

KenCairn also thinks the plan will help the city adapt to the realities a changing climate.

“When I started with the city, we were still having the conversation about ‘How are we going to stop climate change.’ Now we know that we didn’t stop climate change and that climate change is going to happen,” KenCairn says. “In that kind of a context, places have to prepare for extreme conditions of all sorts, including heat and drought. As it turns out, there’s a relationship between soil moisture and the intensity and duration of heat events. The more soil moisture you can hold, the more you’re buffered.”

KenCairn, who likens healthy soil to spraying mist in the air to cool off, says that recovering damaged lands now will prevent the spread of desertification as Colorado gets warmer. The city hopes to help farmers provide nutritious local food in the process. 

“Right now, I’m paying a lot more attention to the germinators on Boulder land. Seeing what works and what doesn’t work,” McCauley said. (Nina Riggio, Special to The Colorado Sun)

“We’re introducing sheep and birds back onto the land, and we’re seeing the pasture come back, the soil regenerate, and we’re doing it by providing the most delicious, nutritious, nutrient-dense food anyone’s had around here,” McCauley says. “Well, I would roll that back. Our grandparents had that.” 

KenCairn says McCauley’s chickens are probably one of the best investments that a Boulder resident could make in combating climate change.

Desertification and deteriorating soils are a global problem. The United Nations estimates that 135 million people could be displaced by desertification by 2045 and that nearly 30 million acres of land could become barren every year, unable to support life. Boulder hopes to help pioneer the role of cities in creating a path back, working with other cities nationally and internationally to meet carbon-sequestration goals.

As for the small plot of Boulder land, things are coming along. Slowly. A year into the venture, McCauley is excited to see plants growing. The next phase is to introduce animals, helping to fertilize the fields. Walking across the pasture, he stops to adjust the water from an irrigation pipe and leans down to inspect the small plants.

“It’s a tricky time because there’s a lot of bindweed over there, the weather might not cooperate. Things could knock us back,” McCauley says. “It took so many extractive processes to get here, it’s going to take a lot to get it back.” 

UPDATE: This story was updated at 10:04 a.m. on June 26, 2019, to include the budget for McCauley’s soil-restoration project.

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