Growing demands of agricultural crops for food, feed, and fuel have expanded globally, which substantially pushes rapid cropland expansion, crop improvement, and management implementation. The important role of agriculture to regional and global greenhouse gas (GHG) emissions has been widely recognized, among which carbon loss resulting from agricultural expansion is an undisputable contributor. However, agriculture-induced land use change is still among the largest and the most uncertain carbon sources, and it is likely to be underestimated by modeling studies as coarse-scale land use data for driving models have represented the sum of bi-directional changes while overlooking sub-grid land cover transitions. As a dominant GHG source, agriculture is challenged to reduce its carbon footprint, that is to reduce the carbon loss per unit of agricultural product gain, while feeding an increasing population. In this study, we investigate the dynamics in carbon footprint of the US western US Corn Belt, a region characterized by rapid cropland expansion over past decade. We reconstructed fine-resolution long-term dataset of land use and management history to drive a process-based land ecosystem model (DLEM) and quantify terrestrial carbon storage change altered by crop production.
Results/Conclusions
We found since 1980, annual production of major grain crops in the western Corn Belt together increased by two thirds, but it has been attributed to different drivers before and after mid-2000s. Our results indicate a substantial increase in carbon footprint of crop production in the US Western Corn Belt. It is not surprising that people pursued more crop production by converting grasslands and wetlands to cropland, but its ecological consequence is tremendous and may take decades to century for soil carbon pool to recover.