<Fig. 11>

4.3 Implications and limitations

Our study explored the spatiotemporal changes of cropland SOC in a rapidly urbanizing area and identified their primary drivers. We found that, although the enhanced soil C input benefited the cropland SOC accumulation during 1980-2000, the rapid urban expansion and industrial economic growth during the subsequent 15 years may lowering SOC due to the decreased soil C input. The urbanizing and industrializing area may overlook the development of agriculture, and the low economic investment in cropland management often caused decreased C input in cropland soils, which implied that the coordinated development of industry, agriculture, and urbanization process is particularly important for cropland SOC sequestration.
Our study investigated the spatiotemporal changes of SOC at a time scale of more than 10 years. However, using the geostatistical method to explore changes in SOC over a shorter time period (i.e., a time period of fewer than five years) may be not feasible, because the detectable changes in SOC still can not be directly measured due to the high stability of SOC pools and slow turnover time of SOC (Yang et al., 2015; Yang et al., 2020). Therefore, the development of new methodologies for incorporating SOC dynamical mechanism into the geostatistical mapping framework (i.e., through the “space for time” method) is necessary.