How does Soil Carbon get Measured?
Soil carbon sequestration refers to the process of transferring carbon dioxide from the atmosphere into the soil of a land region through the process of photosynthesis in plants and trees. There are several techniques used to measure soil carbon sequestration. The choice often depends on the level of precision required, the budget available, and the specific characteristics of the site.
Direct Soil Sampling: This is the most common and traditional method used to measure soil carbon. Soil samples are collected from different depths and locations across a field. These samples are then analysed in a laboratory to determine the carbon content. This process can be time-consuming and labor-intensive but provides a direct measure of soil carbon.
Remote Sensing: This involves using satellite or aerial imagery to assess soil carbon levels. Specific spectral bands can provide information about vegetation cover, which can be related to soil carbon sequestration. This method can cover large areas but may not be as precise as direct sampling.
Eddy Covariance Towers: These instruments measure the exchange of carbon dioxide between the ecosystem and the atmosphere, providing a direct measure of carbon sequestration. They are typically used in research settings and can cover larger areas than soil sampling but are expensive to install and maintain.
Modelling and Simulation: Computer models can simulate soil carbon dynamics based on parameters such as soil type, vegetation cover, climate, and management practices. These models can provide estimates of soil carbon sequestration over large areas and long time scales but rely on the accuracy of the input data and model assumptions.
Infrared Spectroscopy: This method uses the interaction of infrared radiation with soil to estimate the soil carbon content. This technique can be faster and cheaper than traditional lab analyses but may require calibration with direct soil samples.
Isotopic Analysis: This involves tracking the movement of carbon isotopes (e.g., carbon-13) through the soil-plant-atmosphere system. This can provide a measure of carbon sequestration but is typically used in research settings due to its complexity and cost.
Each of these methods has its strengths and limitations, and often multiple methods are used in combination to improve the accuracy of soil carbon sequestration measurements.
In a Carbon Sync project, soil carbon is measured by taking soil samples. In the case of a soil carbon project, baseline samples are taken at the beginning of the project. Then, further samples are taken throughout the life of the project to determine changes in soil carbon sequestration.
Soil core samples are taken to a maximum of one metre in depth from the surface of the soil. The soil is then analysed in a laboratory to determine the carbon stocks in the soil. Agricultural producers are paid (in the form of carbon credits) for increases from the baseline measurements.