Increase in soil organic carbon by agricultural intensification in northern China

[摘要] Agricultural intensification has contributed greatly to the sustained foodsupply of China's population of 1.3 billion over the 30-year period from 1982to 2011. Intensification has several and widely recognized negativeenvironmental impacts including depletion of water resources, pollution ofwater bodies, greenhouse gas emissions and soil acidification. However, therehave been few studies over this period on the impacts of intensification onsoil organic carbon (SOC) at the regional level. The present study wasconducted in Huantai County, a typical intensive farming region in northernChina, to analyze the temporal dynamics of SOC influenced by climate andfarming practices. The results indicate that from 1982 to 2011, SOC contentand density in the 0–20 cm layer of the cropland increased from7.8 ± 1.6 to 11.0 ± 2.3 g kg⁻¹ (41%) and from21.4 ± 4.3 to 33.0 ± 7.0 Mg ha⁻¹ (54%), respectively.The SOC stock (0–20 cm) of the farmland for the entire county increasedfrom 0.75 to 1.2 Tg (59%). Correlation analysis revealed thatincorporation of crop residues significantly increased SOC, while an increasein the mean annual temperature decreased the SOC level. Therefore,agricultural intensification has increased crop productivity and contributedto SOC sequestration in northern China. In the near future, more appropriatetechnologies and practices must be developed and implemented for amaintenance or enhancement of SOC in this region and elsewhere in northernChina, which also reduce non-CO₂ greenhouse gas emissions, since theclimate benefit from the additional SOC storage is estimated to be smallerthan the negative climate impacts of N₂O from N fertilizer additions.

[学科分类] 地球化学与岩石