There is a lot of information on the Internet about how an individual can lower or negate their carbon usage through various techniques and strategies but much less information on what a person can do actively practice techniques of carbon capture to offset their emissions. The obvious example here is planting tree’s but are there any other carbon negative practices that are reasonable for an individual to engage in given a fairly standard income?
It is much easier to avoid emissions than to capture CO2. Anyway, one can roughly prioritize as follows:
Leave it to professionals.
There are expert organizations that focus on CO2 reduction. This is where you have the highest impact per dollar. They mostly work in developing countries, where the reduction per dollar is biggest. Here is a ranking for US-based organizations.
Avoid personal emissions.
Air travel and meat are the most relevant activities, you probably already know about that, but here is a link with tips for a lower carbon life anyway.
This is where the answer to your question starts, since these points actually capture carbon.
Reforestation, plant trees.
There are studies which show that reforestation has a huge potential. Scotland, for example, does a large scale reforestation, almost any country has its own tree-planting-events. You can certainly find one nearby and contribute personally.
Bogs capture and store huge amounts of CO2, but are often drained for land use. In the process, they emit CO2, roughly 0.5 t per hectare and cm water column.
Prefer (local) wood as a construction material. - The carbon captured by the trees gets sequestered away for 50-odd years as building materials. It also helps to source materials locally as this will minimise the emissions from transportation.
Large amounts of CO2 can be captured by shellfish, who build their shells with calcium carbonate, where the carbon comes from CO2 from the atmosphere (scientific, entertaining) As an individual you could make farmed shellfish a part of your diet, although frankly I doubt that this has a significant effect, also accounting for transportation and such.
This list is by far not complete, please feel free to edit, extend and elaborate.
I suggest a variation on juhist's forest landfill proposal:
Assuming budget isn't an issue, and you're very patient, I'd suggest: buy land adjacent to a viable (native or at least non-monocultural) forest. Encourage the forest to expand onto it. Remove trees at a sustainable rate (you'll need to study forestry a little, did I mention that?) and use them for some long lasting purpose (i.e. not firewood or paper). Then when you don't need more any wood cut down trees and convert them into biochar. Bury the biochar into soil (good for soil fertility). You may even be able to sell it.
You don't want to do this in an area where you're going to cause significant carbon release from the soil if the trees dry it out - so don't reforest waterlogged peatland! Grazing pasture adjacent to woodland is probably a good bet.
In terms of what one person can do, this is a lot of work to provide a not hugely significant offset for a high carbon lifestyle, so addressing that should of course be the first port of call.
Looking beyond strictly individualistic action, getting involved in restoration of peatland, as Rainer Glüge suggested, or of native forests (e.g. Trees for Life) is a good option.
You can start growing an exploiting a Moso bamboo forest.
Bamboo is known for growing fast and storing a lot of CO2.
It is said that one hectare of Moso Bamboo can store up to 250 tons of carbon. Each year, a hectare of Moso bamboo absorbs 5.1 tons of carbon.
The obvious example here is planting trees.
No, planting a tree is not a good example of carbon capture.
There are not one but two flaws in it:
Firstly, if you don't plant a tree in some place, and the place could support the growth of a tree, then a tree will actually naturally appear in this very location! Trees, like all other species, are efficient in reproducing. Forest grows without being planted.
Secondly, what will you do when the tree reaches an old age? Many ecofascists think it should be left there so you don't chop it down. Unfortunately, when the tree is large, it will not anymore act as an efficient carbon sink. The carbon sink stage is during the fastest growth stage. When it is fully grown, the carbon flows are in balance.
If you want to capture carbon, you should not plant trees but chop down and bury trees into anaerobic conditions.
When you chop down trees, you create room for more forest to grow. In the fast growth stage, the forest will act as a very efficient carbon sink.
That leaves the problem of the fact that the chopped down trees will naturally decompose, releasing the carbon back to the atmosphere. To prevent this, you need to make something that is long-lasting from it.
One obvious choice would be constructing a wooden house. However, someone will move to the house, start to consume heating energy, etc. so it is not really sustainable business to construct houses for people.
The pulp and paper industries will happily accept each and every tree you chop down. However, their products like toilet paper will store the carbon only for very short periods, releasing it back to the atmosphere very quickly. Not acceptable.
So, the chopped tree should be ideally stored in anaerobic conditions so that it will not decompose.
Solution: dig a large hole to the ground and store the chopped trees there.
Well, planting one canopy shade tree in the front yard requires a careful mapping of the utilities. But an individual could offer a service of planting front yard trees. One note, in many climates a hardwood tree shades the house in summer but lets sunlight through in winter.
The individual could become an advocate of industrial processes that make plastic from carbon-dioxide captured at fossil-fuel powerplants. Then that plastic could be used in long-term building materials that are then required by legislated building code.
Furthermore, the individual could become a farmer of Empress Splendor tress for lumber since the lumber can have long term use as a building material. (I like sorghum for carbon-neutral energy but that's carbon-neutral not carbon-capture.)
Let them live
A livable solution to re-store carbon (who also avoid releasing some more in the process) would be to let wildlife to develop itself without too much disturbance. In my view, this is far more ethical than converting existing land to something agricultural.
Keep this in mind: the fewer you earn, the fewer you destroy life space for wildlife. But if your goal is (food, body, health, sex) security, then you must capt more energy than the others (life forms, peoples, computers, robots, you name it).
An example of this is agriculture on living soil: instead of using huge machinery and chemicals to grow food with very low Energy Return On Invest [EROI], you let the soil live and use manual work to produce reaching EROI>>1, like it necessarily was in the old time where there was no fossil fuel use.
Sure this is not the happy life most of Internet people like us live, but if you include all earth people, then it is what lot of them already do with "standard income" (think of people with less than a 1$ a day). But the idea is the same with this answer (with this reference): store carbon in your backyard if you have one.
Don't forget that a tree's leaves that fall and the grass clippings you collect when you mow your lawn also contain carbon.
If you leave them alone, they will rot and all their carbon content return to the atmosphere. However if you turn this material into biochar, the resulting pure carbon is not bio-available and therefore won't return to the atmosphere.
Biochar retorts can be built from barrels and pieces of pipe. You burn 70% of the collected material to decompose the remaining 30%, the combustible gases that form in the process is also burned.
All carbon that burns in the process came from the atmosphere when the plant grew and part of it is permanently stored in a form of char.