A new study published in Environmental Science and Ecotechnology reveals that human activities like tillage and compaction are breaking the natural link between soil organic carbon and bulk density in coastal zones. Researchers collected 123 soil profiles across China's Jiangsu coast, sampling down to one meter at 10 centimeter intervals. They found that in natural salt marshes, carbon and density follow a predictable negative correlation, but this relationship disappears in croplands and other human modified areas. Traditional pedotransfer functions used to estimate bulk density from carbon content performed poorly in disturbed soils, with prediction uncertainty of 0.22 g per cubic centimeter. The study recommends a land cover based sampling strategy for blue carbon accounting. In vegetated wetlands, high resolution vertical sampling is needed to capture the carbon density gradient. In tidal flats, less intensive sampling works. For human modified lands, the authors say direct measurement of bulk density is necessary because standard formulas fail. This research provides a practical framework to reduce uncertainty in coastal carbon budgets and support better management of these ecosystems.
