You would need to either bury it in a way that it won't be decomposed by microbes. Anaerobic digestion produces methane which is ~83x worse than CO2 as a green

You would need to either bury it in a way that it won't be decomposed by microbes. Anaerobic digestion produces methane which is ~83x worse than CO2 as a greenhouse gas. The alternative is to gasify it, and produce biochar (a.k.a terra preta), a form of carbon that is mixed with the soil to improve it's nutrient and water retention, friability and microbial activity. Biochar is theorized to be stable for 10k years in the soil.