Abstract: To examine the effects of different tillage modes and fertilization measures on the cropland soil organic carbon in the North China Plain, a field experiment was conducted in the Wuqiao County of Hebei Province in 2009-2012. Four tillage treatments (rotary tillage, RT; subsoiling, ST; plough tillage, PT; notillage, NT) combined with three fertilization measures (manure and chemical fertilizer, MF; straw-returning and chemical fertilizer, SF; chemical fertilizer, CF) were installed, and the variations of total organic carbon (TOC) and particulate organic carbon (POC) contents in 0-20 cm soil layer were observed. Three-year continuous tillage (including RT, ST, and PT) decreased the soil carbon sequestration to some extent, while no-tillage was conducive to the increase of the carbon sequestration. As compared with 3-year continuous no-tillage, 2-year notillage after 1-year subsoiling could sequestrate more carbon, and the TOC and POC contents were 8% and 2% higher, respectively. Two-year NT after 1-year PT benefited the restoration of soil carbon, its TOC ratio being restored from 0.74 under 3-year continuous NT to 0.93, and its POC ratio being restored from 0.59 to 0.94. As for the fertilization measures, MF had the best effect on maintaining soil carbon sequestration, followed by SF, and CF. In sum, the optimal combination of tillage mode and fertilization measure for the soil carbon sequestration in North China Plain could be sub-soiling once followed 2-year no-tillage, combined with manure application or straw-returning.

Key words: urbanization, eco-environment, coupling coordination, Jilin Province.