Modeling impacts of carbon sequestration on net greenhouse gas emissions from agricultural soils in China
Modeling impacts of carbon sequestration on net greenhouse gas emissions from agricultural soils in China
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DOI：
10.1029/2008gb003180
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发表时间：
2009-02-18
影响因子：
5.2
通讯作者：
Van Ranst, Eric
中科院分区：
文献类型：
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作者：
Qiu, Jianjun;Li, Changsheng;Van Ranst, Eric
由于我国长期的集约化耕作，许多农田的土壤有机碳（SOC）含量已经耗尽。鼓励中国农民在农场采用替代管理方法来隔离有机碳。根据中国农村地区碳（C）资源的可用性，最有前途的做法是（1）在土壤中掺入更多农作物残留物；（2）恢复传统的粪肥。通过实施替代做法，在某些领域观察到 SOC 含量有所增加。本文研究了碳封存策略如何影响中国六个选定地点农业土壤中一氧化二氮 (N2O) 和甲烷 (CH4) 的排放。该研究采用基于过程的模型反硝化分解（DNDC），该模型已根据在中国观测到的 SOC 动态以及 N2O 和 CH4 通量数据集进行了广泛验证，以量化六个农业生态系统不同气候、土壤和作物轮作条件下加强作物残留掺入和粪便改良对温室气体的影响。模型结果表明：（1）当采用替代管理做法时，碳封存率增加，但这些做法的 N2O 或 CH4 排放量也增加； (2) 减少合成肥料的施用量并结合替代做法可以减少 N2O 排放，同时保持现有的作物产量和碳固存率。该建模方法有助于在大区域范围内开发空间差异化的最佳管理实践。
Soil organic carbon (SOC) contents in many farmlands have been depleted because of the long-term history of intensive cultivation in China. Chinese farmers are encouraged to adopt alternative management practices on their farms to sequester SOC. On the basis of the availability of carbon (C) resources in the rural areas in China, the most promising practices are (1) incorporating more crop residue in the soils and (2) resuming traditional manure fertilizer. By implementing the alternative practices, increase in SOC content has been observed in some fields. This paper investigates how the C sequestration strategies could affect nitrous oxide (N2O) and methane (CH4) emissions from the agricultural soils in six selected sites across China. A process-based model, denitrification-decomposition or DNDC, which has been widely validated against data sets of SOC dynamics and N2O and CH4 fluxes observed in China, was adopted in the study to quantify the greenhouse gas impacts of enhanced crop residue incorporation and manure amendment under the diverse climate, soil, and crop rotation conditions across the six agroecosystems. Model results indicated that (1) when the alternative management practices were employed C sequestration rates increased, however, N2O or CH4 emissions were also increased for these practices; and (2) reducing the application rates of synthetic fertilizer in conjunction with the alternative practices could decrease N2O emissions while at the same time maintaining existing crop yields and C sequestration rates. The modeling approach could help with development of spatially differentiated best management practices at large regional scales.