That's incorrect, if you look into regenerative agriculture you'll see that soil carbon content can be increased from 1 to 8 percent in less than a decade. Carbon sequestration isn't just from biomass above the soil, it also occurs through carbohydrate transfer to microbes and as a result of the increase in microbial biomass in soils.

Until they catch fire and release that CO2 right back into the atmosphere.

We’ve seen this happen with carbon capture programs already.