Dynamic change of soil organic matter and its affecting factors at county level

The study of the long-term dynamic change of soil organic matter (SOM) and its affecting factors of geoponic practices were important for a comprehensive management on soil fertility. In this paper, based on the soil fertilizer monitoring data in 1980 and 1999 at county level, household survey and statistics data, the dynamic change of soil organic matter (SOM) content and its affecting factors by relevant agricultural practices in the past twenty years were analyzed comprehensively. The results indicated SOM content in the surface layer took on a rising tendency in the last twenty years in Quzhou,Hebei province. The change of geoponic practices, including the dosage augment of fertilization, straw returning to field, reclamation of salinity soil, increment of irrigation area, enhancement of index of multiple plantation and positive SOM balance of the dominant cropping pattern and crop planting, contributed to the increment of SOM. Although the SOM content was improved, the current agricultural practices brought on a series of ecological problems as well. Implementation of conservation tillage, decrease of chemical fertilizer application, increment the rate of straw returning to field and organic fertilizer, should be the primary regulation direction of geoponic management in the future.