| 摘要: |
| 【目的】以黄土高原不同地貌气候类型区农田土壤为研究对象，研究农田土壤有机碳与其他理化属性的关系，探讨影响有机碳的土壤因子，为区域农田土壤固碳影响因素及固碳现状评估提供理论依据。【方法】采用多专题数据图综合分析方法，考虑土地利用、种植制度、地形地貌、土壤类型等将黄土高原地区划分为5个地貌类型区，在每个地貌类型区选取一个典型县，结合“联合单元布点法”进行样点布设，运用逐步线性回归模型、回归树模型和相关性分析研究不同地貌类型区农田土壤有机碳与其他理化属性的关系。【结果】1）不同地貌类型区农田土壤有机碳与pH、砂粒含量呈显著负相关关系，与粉粒含量、全氮、全钾呈显著正相关关系，该相关性受气候和管理措施影响较小；与体积质量、黏粒含量呈负相关，与全磷、有效磷、速效钾呈正相关，该相关性受气候和管理措施影响较大。农田土壤有机碳与黏粒含量的相关关系和黏粒含量有关，当黏粒含量为20%~25%，有机碳与黏粒的相关性较高；当黏粒含量大于30%时，有机碳与黏粒呈负相关趋势。2）区域尺度上，全氮、体积质量、全磷是影响农田土壤有机碳含量的重要因子；在各个地貌类型区中，全氮是影响农田土壤有机碳含量的重要因子。关中平原区、渭北高塬区、丘陵沟壑区、银川平原区、浅山丘陵区有机碳处于最高水平时的全氮阈值分别为1.39，0.95，1.33，1.38，1.64 g/kg，有机碳处于低级水平的全氮阈值分别为0.97，0.59，0.86，0.76，1.06 g/kg。【结论】黄土高原不同地貌类型区农田土壤有机碳与其他理化属性的相关性存在较大差异，且受气候和管理措施影响的程度不同。整体来看，全氮是影响黄土高原全区及各县域农田土壤有机碳的重要因子。 |
| 关键词: 农田土壤有机碳 土壤理化性质 回归树模型 逐步线性回归模型 黄土高原 |
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| 基金项目:科技基础性工作专项（2014FY210100）；中国科学院战略先导科技专项（XDA05050504）；国家自然科学基金项目（41171422） |
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| Relationship between cropland soil organic carbon and others physicochemical properties in different landforms of the Loess Plateau |
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LI Binbin,XU Mingxiang,LI Panpan,et al
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| Abstract: |
| 【Objective】This study revealed the relationships between soil organic carbon (SOC) of cropland and soil properties and identified the soil attributes that influence SOC among different climate-landform areas on the Loess Plateau.【Method】For revealing the relationships and identifying the powerful soil attributes among different areas,correlation method,classification,regression tree (C&RT) and stepwise linear regression analysis were used based on the typical counties selected from five landform areas. 【Result】1）The correlations between SOC and soil chemical properties were much more closer than soil physical properties.SOC was correlated positively with silt content and soil nutrients and negatively correlated with pH,bulk density and clay content.Among them,climate and management practices had relatively little influence on the relationships between SOC and sand,silt,pH,total potassium,and total nitrogen.Nevertheless,the relationships between SOC and bulk density,clay,total phosphorus,available phosphorus and potassium were affected greatly by climate and management practices.2）Total N,bulk density and total P were the main influencing factors of SOC at regional scale on the Loess Plateau,while total N was the main influencing factor in different climate-landform areas.Thresholds for total nitrogen when SOC reaching the highest levels in Guanzhong Plain,Weibei Gully region,Hilly and Gully region,Yinchuan Plain and Shallow mountain and Hilly region were 1.39,0.95,1.33,1.38,and 1.64 g/kg,respectively,and the values when SOC reaching the minimum levels were 0.97,0.59,0.86,0.76 and,1.06 g/kg,respectively.【Conclusion】Significant differences existed in SOC and soil properties in different climate-landform areas on the Loess Plateau and the effects of climate and management practices. As a whole,total nitrogen is the most important factor. |
| Key words: soil organic carbon of cropland soil physicochemical properties regression tree model stepwise linear regression analysis Loess Plateau |
