The most important thing you need to know about the oxalate carbonate pathway, is that
FUNGAL activity increases this nutrient exchange between soil and plant.
So...Focus on increasing the mycorrhizal+mycelial networks in the soil to capitalize on this “pathway.” Try not to get hung up on some species that some scientists says has a higher oxalate-carbonate pathway...
When you DO choose a carbon source to farm, consider the long term provisions, too. We don’t carbon-farm strictly for the sake of farming carbon, we have to feed people too.
So one of the most important questions you can ask yourself, is: What would you/your inheritors do with the product?
Could they eat an entire farm of prickly pear? Or could they sell Timber or build homes with African teak after a couple decades?
And even still: Beware that you don’t fall into the modern mindset of monoculture!
One big field of primarily just one thing, isn’t very good for any of us... I encourage everyone to deeply consider the synergistic polyculture that could be created with the same amount of effort as a massive forest of cactus...