Conservation tillage, in the best sense, includes cover crops. In addition to enriching the soil, cover crops literally inhale carbon dioxide from the air and use it for plant growth. What isn’t used for growth is eventually released back into the soil.
According to the Conservation Technology Information Center (and the United Nations Food and Agriculture Organization). upwards of ONE THIRD of the carbon emitted in our world (from power plants and internal combustion engines) could be offset if farmers worldwide would all make use of conservation tillage, including cover crops.
Annual ryegrass, as a cover crop, is adept at absorbing carbon and storing it in its massive network of roots. When killed in the spring, the annual ryegrass residue (including the roots) releases its sequestered nitrogen to help fertilize the new corn and beans in the field. At the same time, the carbon in the cover crop is released into the soil, improving the ratio of organic matter and adding to the food source for soil microbiology.