The whole reason we had the second stage of the Industrial Revolution is that if you use trees instead of mining then you're limited in energy by the acreage you can devote to trees and that goes down with extra farming as the population increases. To simplify horribly that's why the Ming iron industry with it's chain suspension bridges and so forth collapsed.

If you're removing carbon from the air by burying trees then you'll only be able to sustain the energy intensity of civilization in the Britain of 1800, plus what we can get with renewables. What this new form of capture gives us is the ability to get rid of excess carbon without using huge amounts of arable land to do it.