Terrestrial Carbon Sequestration Frequently Asked Questions
What is meant by terrestrial carbon sequestration?
Terrestrial carbon sequestration is essentially the process of transforming carbon in the air (carbon dioxide or CO2) into stored soil carbon. Carbon dioxide is taken up by plants through the process of photosynthesis and incorporated into living plant matter. As the plants die, the carbon-based leaves, stems and roots decay in the soil and become soil organic matter. This is the basic process of terrestrial carbon sequestration.
How can terrestrial carbon sequestration help reduce global warming problems?
Atmospheric carbon dioxide and other greenhouse gases act to trap heat that is reflected from the earth’s surface. This buildup of heat could lead to global warming. Through terrestrial carbon sequestration, atmospheric carbon dioxide levels are reduced as soil organic carbon levels increase. If the soil organic carbon is undisturbed, then it can remain in the soil for many years as stable organic matter. This carbon is then sequestered or removed from the pool available to be recycled to the atmosphere. This process reduces CO2 levels in the atmosphere, reducing the chances of global warming.
How much impact can terrestrial carbon sequestration have on greenhouse gases?
It has been estimated that 20% or more of targeted CO2 emission reductions could be met by agriculture soil carbon sequestration.
What can agricultural producers do to enhance terrestrial carbon sequestration?
a. No-till or reduced-till
b. Diversified crop rotations
c. Reduce Summer Fallow
d. Vegetation Buffers
e. Conservation measures that reduce soil erosion
f. Using higher residue crops, such as corn, grain sorghum and wheat
g. Winter cover crops
h. Selecting varieties and hybrids that store more carbon
i. Reduce soil inputs
j. Convert marginal agricultural land to grassland or forest
What can grazingland managers do to enhance carbon sequestration?
a. Improve forage quality
b. Regular use of prescribed burns to increase forage productivity
c. Reduce overgrazing
d. Improved grazing practices
What is soil organic matter, where does it come from and where does it go?
Soil organic matter consists of decomposed plant and animal matter. It helps bind soil mineral particles together into clumps, called soil aggregates. Higher levels of soil organic matter lead to more stable soil aggregates, better soil infiltration capability and aeration, better water-holding capacity , more resistance to wind erosion, reduced potential for compaction, and better overall soil fertility. Organic matter helps hold soil nutrients in place, so they are not lost to runoff or leaching. If left undisturbed, soil organic matter can eventually be transformed into long lasting humus, a very stable form of organic matter. However, if the soil is tilled, soil organic matter will be oxidized and carbon will be lost to the atmosphere as CO2. If the soil eroded, organic matter will be removed with runoff water.
What affects the level of soil organic matter?
Native levels of soil organic matter for any particular site are determined largely by the latitude location on the earth and by the annual precipitation received. Native soil organic matter levels will generally increase as you move either north or south of the equator. In the Great Plains of the United States, organic matter levels increase from west to east following the precipitation gradient. Management by man can change the soil organic matter level. In general, as cropping intensity increases, soil organic matter increases. In addition, as tillage frequency increases, soil organic matter decreases. For Montana producers, eliminating periods of fallow and using no-tillage management practices provides the greatest potential to increase soil organic matter levels at a given location.
How many acres of forestland does it take to offset the carbon dioxide emissions from medium-sized coal-fired power plant?
Roughly speaking, about 220,000 acres would be required to offset emissions from an average size power plant. This assumes an average coal power plant from the existing fleet and a forest uptake rate of 3 tons of carbon per acre per year (Newel and Stavins, Journal of Environmental Economics and Management 40, 211-235, 2000. Figure 1 without discounting).
Terrestrial sequestration is conceptualized for use in conjunction with carbon dioxide capture and storage to provide fossil fired power generation with zero net greenhouse gas emissions. It is expensive to capture the +last 5-10% of carbon dioxide emissions from a fossil fuel conversion plant, due to the law of diminishing returns. A cost-effective approach for zero emissions is to capture 90% of emissions and offset the remaining 10% with forest land. Moreover, forestation and other terrestrial sequestration approaches offer many collateral benefits including flood protection, wildlife/endangered species habitat, restored ecosystems, etc.
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