Food waste that ends up on a landfill site is the third-largest contributing factor to climate change. Converting food waste into compost is an essential part of combatting climate change. Compost added to soil has a significantly higher carbon content compared to soils that have not been composted. This carbon sequestration can save our planet.
Soil and climate change
It’s no secret that organic farmers believe in compost, but just what role compost plays in soil’s ability to store carbon – and keep it out of the atmosphere, where it contributes to climate change – has been less clear.
A recent study out of the University of California, Davis suggests that compost plays a more significant role than once thought in building soil carbon.
It also found that carbon levels fluctuate more in deeper soil than most evaluation methodologies tend to account for. In practical terms, the findings could mean agricultural incentive programs have undervalued compost and that we’ve measured carbon levels in soil all wrong.
Nicole Tautges, a co-author of the study, says it wasn’t a surprise to find that compost is good at helping soil store carbon – it’s where exactly it does this that was revealing.
“The surprising piece was that it raised soil carbon between one and two meters deep. Because the big question is, ‘How does the carbon get down there when we’re only applying it in the top foot?'” adds Tautges, the chief cropping systems scientist at the UC Davis Agricultural Sustainability Institute.
Her team has hypothesized that it has to do with how water moves through the soil, and they plan to continue studying its movement. But just demonstrating the importance of soil depth could be significant, both for increasing the value that farmers and policymakers place on compost application and, eventually, for how soil carbon measurements are taken.
“When you only measure the top foot, there’s potential to both over-and underestimate carbon storage in our agricultural soils,” says Tautges.