Cropland soil organic matter content change in Northeast China, 1985-2005

Soil organic matter (SOM) content is one of the most important indicators of soil quality and hence the productive capacity of soils. Northeast China (NEC) is the most important region in grain production in China. In this study, we assessed the spatiotemporal change of cropland SOM content in NEC using sampling data of 2005 and survey data of 1985. We also analysed the driving forces behind the SOM content change. Our results showed that SOM content decreased in 39% of all the cropland in NEC, while increase in SOM content was only detected on 16% of the cropland. SOM remained unchanged in nearly half (i.e. 45%) of the cropland. Our results also revealed that cropping intensity and fertilizer application were the two most important factors driving SOM change. Overall, results from this research provided novel details of the spatiotemporal patterns of cropland SOM content change in NEC which was not revealed in earlier assessments. The datasets presented here can be used not only as baselines for the calibration of process-based carbon budget models, but also to identify regional soil quality hotspots and to guide spatial-explicit soil management practices.