[bluGill]

it still decays to things that release that CO2, plus burying things uses a lot of energy. If this a serious proposal you should be thinking grow it, wait for it to dry out and burn it - the fire will not be hot enough to turn all the carbon into CO2, the remainder is elemental carbon (read charcoal) in a form not usable to life. That carbon is also biochar which is actually useful to improve the soil.

This is most easily done in forest, but note that you need regular forest fires, otherwise the fire is hot enough to run all the carbon into CO2 and we didn't gain anything. Thus most of the forest fires you read about are bad - but if we change our policy after the fire and burn those forests often we can make them a net negative CO2.

[chewbacha]

Decomposing biomass is called compost and you can layer it back down on the soil you grow grass-like plants in. This is what forests and prairies do naturally. Some amount of the biomass is left behind and becomes a silt layer.

Carbon emitted from the decay is not net positive into the air. It would still be net negative so long as you didn’t expend fossil fuels to bury it. In fact, I could burn some of the harvest to fuel burying the rest :)

Plus burning it would release the carbon faster than decay, and decay of CO2 into roots is generally just fixes by growing plants again. So the rate of carbon release would be dramatically faster to but versus decay. And what we want is net sequestering so slow release is good.

It’s literally the process that generated a low CO2 high O2 atmosphere in the first place, I’m just proposing we cultivate it and not harvest.

[Reason077]

Alternatively we could also grow forests and, rather than burn them, harvest the wood for constructing furniture, buildings, etc, that will survive long-term. Hopefully, the wood can be recycled when the buildings reach their end of life rather than being burnt or decomposed.

But I suspect we'll need a lot of forests to compensate for the current rate of fossil-fuel use.

[Roodgorf]

As I understand it a push for more bamboo would be great for this. It's relatively quick growing and useful for a lot of various building materials. You could sequester a lot of CO2 in bamboo that would be fairly useful and take a lot less processing than other types of wood.

[chewbacha]

Bamboo is good too, corn captures a lot of carbon as well and dies off quickly, making it good for composting back into the ground. Grown in non-frosting areas you could re-sow year round with plants cultivated for each season.

[AstralStorm]

The trouble is that even bamboo requires marginally arable land which is at premium, fails to grow in cold conditions of most Europe and chunk of US and Russia. The area required to make a dent in CO2 sequestration would be a bunch of countries sized.

Secondary problem would be handling all of that junk. You cannot burn it, have to bury it instead.

[Roodgorf]

That's fair. Though I will say I don't think any single armed approach to sequestration will be anywhere close to reasonable, so exploring any avenue with decent margins, especially if there's any current practical value to it, seems like a smart idea.

What do you mean by "you can't burn it"? It would release some amount of CO2, but as another commenter points out, there would still be a non-zero amount of left over carbon, no?

[AstralStorm]

Well, exploring bad options is a waste of time, luxury we don't have unfortunately.

If you want to go full genetic engineered plants, there are better options out there.