Kevin Muno (left) and John Wick discuss the implications of their composting experiment
Ground was broken in Santa Ysabel on October 13 on an ambitious new project that seeks to prove soil management can be used to fight climate change throughout California and beyond.
"This is all about regenerative agriculture and carbon farming in San Diego County," said Kevin Muno, a cattle rancher and owner of the 80-acre Montado Farms, introducing the project. "By spreading a half-inch of compost on rangeland, we're able to sequester a ton of carbon per hectare [roughly 2.5 acres], increase grass growth by 40 to 60 percent, and reduce water use by three times. I think those are some amazing numbers. The goal is to ramp this up to policy level, so farmers can start getting paid for the value they produce through these ecosystem services."
Muno's statement was referring to the findings of the Marin Carbon Project, which has been studying the effects of composting on two rangeland sites in Northern California for nearly a decade.
"When I started out in 2008, I didn't even know the difference between manure, mulch, and compost," said John Wick, project co-founder and owner of the Nicasio Native Grass Ranch, where much of the project's work has taken place to date. "The conventional wisdom was that all of the carbon in compost would oxidize into the atmosphere, which would be undesirable."
Instead, researchers found that the healthier soil and increased growth of wild grasses were even more effective than trees in scrubbing carbon pollution from the atmosphere — so much so that simply spreading compost over one-half of the state's rangeland and taking no further action could eliminate the same amount of carbon pollution created by all electricity generation activities statewide.
"Now, when we're talking about offsetting an entire sector like this, things get exciting," Wick continued. "There's strong evidence that we could cool the earth right now with what we know."
While trapping carbon in the ground was the group's focus, additional benefits were soon apparent. The increased grass growth provided better, more nutritious forage food for cows, sheep, and other range animals. And each hectare of land was able to retain 26,000 more liters of water in surface soil than before the compost treatment, meaning grasses could grow longer and remain healthier during prolonged periods without rainfall. That amount of water, spread across the state's rangeland, is equivalent to seven million acre-feet, more than all of California currently consumes, Wick said.
"It works. It works in different climates, with different grass, different soil, different management, but the same exact compost," concluded Wick. "That's exactly what we're doing here, we have a batch of compost that's been made for us up in Marin County, and we're hauling it to 17 different locations across the state. If the soil systems respond in the way we anticipate, then it's going to be a very interesting experiment."
Muno's ranch, about 40 miles northeast of downtown San Diego, is the southernmost of the 17 sites across the state where compost research is being expanded. After taking soil samples, researchers will spread one-quarter inch of Wick's compost (half as much as at the initial site, though still expected to provide similar results) over one half of a one-acre site marked off on a hillside. Over the next several years, the soil will be regularly tested to compare results against the original two study sites, which have still shown positive results for all of the noted benefits eight years after the single compost application.
If they're successful, the next question is how to spread the practice to farm and ranch land on a larger scale.
"We have a unique place here in San Diego County, with over 5000 farms including more small farms and organic farms than anywhere in the nation," observed San Diego Food System Alliance executive director Elly Brown. "So we have a great opportunity to encourage these practices."
In order to expand, proponents say, a loosening on rules related to composting activity would be needed, as would a funding source. Brown's group has suggested allocating grant funds to support carbon farming, with funding coming either from the county's general budget, a bond measure in support of the practice, or by imposing greenhouse gas mitigation fees on new development that would be earmarked for offsetting activities.
Initial sampling of the ground at Murtado Farms is expected to be complete, along with spreading of the compost trucked in from Marin, sometime in the coming week.