Carbon sequestration is very important to the whole drawdown concept. Healthy soil stores carbon in its organic matter, and the processes of growing plants on healthy soils maintain the flow of carbon into the soil. I have a small (150 sq. ft.) vegetable garden that I have registered as a Climate Victory Garden, in which I use no pesticides, commercial non-organic fertilizers, or other chemicals. The soil is very rocky, so I do have to do some digging for some root crops like garlic, but otherwise I do not till the soil. I amend the soil with aged horse manure and kitchen compost, plus a bag or two of lobster compost, made from composted ground lobster shells, a by-product of the coastal Maine restaurant industry. I am aiming to get the organic soil fraction up to 8 or 9%. It is getting there!
I also manage the gardens on an estate, which are much more extensive. I make mountains of compost there, using horse manure, hardwood mulch, leaves, and any garden scraps from deadheading, pruning, etc. I use the finished, screened compost as a mulch, topped with regular hardwood bark mulch. The idea is to put as much carbon into the soils as possible, and break up the original heavy clay soil into something more plant friendly, so the plants can continue the work of carbon sequestration.