Accurately measuring the amount of carbon in the topsoil is crucial for managing and protecting soil health. Chinese scientists developed a new method called diagnostic surface horizon (DSH) to better assess topsoil carbon levels. By comparing this new method to the traditional surface horizon method, they found that DSH gives more accurate results. Different types of topsoil have different carbon levels, and using the right thickness for topsoil classification is important. This study shows that using the DSH method can improve the accuracy of topsoil carbon assessments, helping with soil management decisions.