Estimation of a Carbon Stock
As all companies will soon have to report their greenhouse gas emissions or simply just carbon footprint, farms will be no exception. A key source of emissions is cropland and grassland, which are complex systems that both sequester and emit carbon dioxide (CO2). Grassland generally sequesters more carbon than it emits, while cropland ideally balances emissions and sequestration.

Carbon footprint calculations use data from the Czech Hydrometeorological Institute’s (CHMI) National GHG Inventory Reports (NIR). However, these general values don’t reflect the actual state of the soil or the specific amounts of emissions from a particular farm. For more precise calculations, we use a combination of farmer-provided data, such as the area of cropland and grassland, and Soil Organic Carbon (SOC) estimations from 2015-2019 and 2020-2023, derived through spectral analysis of Bare Soil Composites based on Sentinel-2 and Landsat satellite imagery. To calculate the carbon footprint, farms provide data according to the internationally accepted GHG Protocol, including land-use data. Based on NIR reports, an average hectare of cropland sequesters around 1.7 kg of carbon, while a hectare of grassland sequesters about 90 kg. These values are translated into CO2 equivalents (which is about 6.24 kgCO2 and 330 kgCO2, respectively). However, the NIR data is somewhat distorted as it includes various land uses like vineyards and orchards, which sequester carbon differently. Moreover, arable land tends to degrade, losing organic matter, which contributes to CO2 emissions rather than sequestration. A more specific approach to calculating carbon footprint involves spectral analysis of individual parcels, factoring in the SOC index, soil bulk density, and soil depth. The reason for this is that the content of soil organic matter changes too slowly to measure relevant changes within one year, so the change of SOC had to be calculated as a difference of longer time periods (in this case 2015 – 2019 and 2020 – 2023). Additionally, nitrous oxide (N2O) has been considered due to its emission during soil carbon mineralization. The project findings reveal that arable land is both a source and a sink for CO2 and N2O, but the overall impact on the farm’s carbon footprint is minimal. Spectral analysis also identifies additional grassland not recorded in official registries, which improves the carbon footprint calculation by accounting for extra sequestration. Although the difference between general and specific calculation methods is minor (less than 0.5%), the specific approach offers more accurate data and highlights the significant issue of soil organic matter loss.
Example of the changes in Soil Organic Carbon between 2015 - 2019 (left) and 2020 - 2023 (right).