基于DNDC模型的福建省不同利用类型耕地土壤固碳潜力预估

Future Projection of Soil Carbon Sequestration Potential of Different Cultivated Land Types in Fujian Province Based on DNDC Model

    摘要
  • 摘要:
    目的 明确不同利用类型耕地土壤“碳源/汇”的贡献大小，为合理制定农业碳中和措施提供基础。研究不同利用类型耕地土壤有机碳(Soil Organic Carbon，SOC)的时空演变特征，探讨影响SOC变化的主控因子及其与SOC变化速率（dSOC）的关系，从而定量表征福建省不同利用类型耕地土壤固碳潜力。
    方法 基于农业农村部福建省测土配方施肥项目的230,445个实测样本数据所建立的1∶5万大比例尺土壤数据库，结合DNDC (Denitrification and Decomposition) 模型模拟了2021 ~ 2033年福建省不同利用类型耕地的固碳速率和固碳潜力。
    结果 全省耕地年均dSOC为1.82 kg C hm−2 a−1，固碳总量（TSOC）为39.40 Gg C。其中水田、旱地和水浇地的年均dSOC分别为16.58、−78.08和−126.22 kg C hm−2 a−1，TSOC分别为306.93、−195.21和−72.33 Gg C。从空间分布来看，福建省耕地dSOC总体上呈现西北内陆低、东南沿海高的分布格局，且水田高于旱地和水浇地。从时间序列来看，水田dSOC、TSOC和土壤有机碳密度（Soil Organic Carbon Density，SOCD）的变化特征与全省耕地相似，且显著高于旱地和水浇地。初始SOC含量是影响各利用类型耕地年均dSOC的主要驱动因素，降雨通过影响初始SOC含量及土壤pH值间接影响dSOC。
    结论 福建省耕地土壤表现为弱的碳汇，其中以水田碳汇为主，旱地和水浇地表现为碳源。因此，应在保持经济效益和作物生长的前提下增加水田有机肥投入量，针对旱地和水浇地注重雨季排水、施用生物炭肥。

     

    Abstract:
    Objective The determination of soil "carbon source/sink" contributions in different use types of cultivated land is fundamental for the development of effective agricultural carbon (C) neutrality strategies. This study analyzed the temporal and spatial evolution characteristics of soil organic C (SOC) across different use types of cultivated land, identified key factors influencing SOC changes, and examined their relationship with the rate of SOC change (dSOC) to quantify the carbon sequestration potential of different use types of cultivated land in Fujian Province.
    Method A 1∶50,000 large-scale soil database was established based on 230,445 measured samples from the Fujian Provincial Soil Testing and Fertilizer Recommendation Program under the Ministry of Agriculture and Rural Affairs. Combined with DNDC (Denitrification and Decomposition) model, the C sequestration rate and C sequestration potential of different types of cultivated land under current agricultural management measures in Fujian Province from 2021 to 2033 were simulated.
    Result The average annual dSOC of cultivated land, paddy land, dry land and irrigated land in Fujian Province were 1.82, 16.58, −78.08 and −126.22 kg C hm−2, respectively, with corresponding total C sequestration (TSOC) of 39.40, 306.93, −195.21 and −72.33 Gg C. From the perspective of spatial distribution, the dSOC of cultivated land in Fujian showed a low distribution in northwest inland regions and high distribution in southeastern coast areas, with higher SOC in paddy fields than those in dry land and irrigated land. From the perspective of time series, the trends in dSOC, TSOC and soil organic C density (SOCD) for paddy field were similar to those of all types of cultivated land, and significantly higher than those of dry land and irrigated land. Initial SOC was found to be the primary driving factor of annual dSOC in cultivated land across different utilization types, while rainfall indirectly affected the dSOC through its impact on initial SOC content and soil pH value.
    Conclusion All types of cultivated soil in Fujian Province functioned as weak C sinks, with paddy fields serving as the primary C sink, while dry land and irrigated land acted as the C sources. Therefore, the application of organic fertilizer in paddy fields under the premise of maintaining economic benefits and crop growth should be increased, while attention should be given to drainage and the application of biochar fertilizer in dry land and irrigated land during the rainy season.

     

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