Farmers Want to Create San Diego's Carbon Dumps The county committed to being carbon-neutral by 2035 but it will have to create many projects to capture carbon to hit that goal. Farmers could help – but only if the rules change to make it easier. Bea Alvarez pierced the Pauma Valley earth with the metallic bit of her cylindrical soil tester. She’s been tracking the amount of carbon her farm retains if she adds compost and rarely tills the land. Tilling exposes carbon from dead plants to oxygen in the air, creating carbon dioxide, which is the planet’s most troublesome climate-changing gas.