钙对黑垆土农田土壤有机碳固持的作用及机理

Soil organic carbon usually determined the productivity of farmland ecosystem, and has an important influence on greenhouse gases emission and climate change. Soil calcium closely related to soil aggregate, organic-mineral complex and other soil organic carbon sequestration mechanism. Heilu soil developed on the loess parent material, its distribution occupied most area of the loess plateau. However, there is little information about the impact of calcium on soil organic carbon stock in Heilu soil. This project based on a long-term Heilu soil experiment (set up in 1978) and a calcium and organic fertilizer coupling laboratory cultivation experiment, using scanning electron microscope(SEM) and nuclear magnetic resonance (NMR) measurement technologies to study calcium’s role on Heilu soil carbon sequestration mechanism. Firstly, we study the influence of calcium on soil aggregates and organic carbon content in the water stability aggregate and aggregate microstructure to probe the calcium’s role on soil organic carbon physical protection mechanism. Secondly, we study the effects of soil calcium on calcium key complex content and organic carbon content in calcium key complex and calcium key complex’s microstructure to seek the influence of calcium on soil organic carbon chemistry protection mechanism. Thirdly, we study carbon functional groups of soil humus composition, soil aggregate and calcium key complex to discuss calcium role on soil organic carbon's self protection mechanism. Lastly, we study the effect of calcium on soil organic carbon fixed rate. Through these study of above, we overall and systematically reveal calcium’s role on soil organic carbon hold mechanism in Heilu soil. Through the research of this project, we will propose efficiently improved soil organic carbon stock technology 1-2 items, apply for patent 1-2 items and publish academic paper 4-7 pieces.

土壤有机碳决定着农田生态系统的生产力，同时对全球气候变化有重要的影响。钙与土壤团聚体、有机无机复合体等土壤固碳机制密切相关。黑垆土是由黄土母质发育而成，占据了黄土高原的大部分面积。项目以黑垆土长期定位试验（始于1978年）及钙和有机肥耦合培养试验为基础，应用扫描电镜、核磁共振等测试技术，通过研究钙与土壤水稳性团聚体和其中有机碳含量及团聚体微结构的影响，探讨钙对土壤有机碳库物理保护机制的作用；研究钙对钙键复合体有机碳含量及钙键复合体微结构的影响，探讨钙对土壤有机碳库化学结合保护机制的作用；研究钙对土壤腐殖质组分、团聚体、钙键复合体及团聚体中含碳官能团的影响，探讨钙对土壤有机碳自我固持能力的作用；研究钙对土壤有机碳固定率的影响，探讨钙对土壤有机碳的固持效果，从而系统揭示钙对土壤有机碳固持的作用及机理。通过项目研究，发表学术论文4-7篇，申报专利1-2项，研制出土壤快速固碳技术1-2项。

通过1978年设置在黑垆上的长期定位试验，研究钙与土壤有机碳库的相互关系、钙对土壤有机碳库物理保护机制的作用、钙对土壤有机碳库化学结合保护机制的作用及钙对土壤有机碳固存率的影响。还研究了施肥对作物产量及土壤肥力的贡献、施肥、土壤肥力和作物产量的关系、施肥对土壤有机碳库及结合态腐殖质的影响及施肥对团聚体及有机无机复合体的影响。结果表明：长期平衡施用化肥、秸秆还田、施用有机肥及有机肥与化肥配施可提高黄土高原黑垆土的作物产量、土壤有机碳和全氮含量。黄土高原黑垆土区小麦/玉米轮作体系中，长期秸秆还田、施用有机肥及有机肥与化肥配施作物产量较常规施肥增加，同时也可提高土壤有机质和全氮含量，若秸秆还田，可隔年施磷。. 土壤有机质含量每增加1g/kg，土壤全氮的增幅为0.028 g/kg。土壤全氮每增加1g/kg，玉米和小麦籽粒产量的增幅分别达到12175kg/hm2和6507 kg/hm2，增加土壤全氮含量对增加作物产量有及其重要意义。有机碳土壤固存率与有机碳投入量及其质量都有着密切的关系，有机碳投入量低，固存率高，投入量高，则固存率低，腐殖质化程度高的有机物土壤固存率高。结合态有机碳占土壤有机碳的绝大部分。. 长期施肥有机肥可以显著增加了耕作层土壤游离态有机碳，长期施用有机肥及秸秆还田显著增加耕作层（0-20cm）松结态有机碳含量，其分别较对照（CK）增加194%、149%和165%，而且稳结态有机碳含量分别较对照增加125.87%、58.12%和95%，而施有机肥对0—20cm土层紧结态有机碳含量影响不显著。. 团聚体越小，有机碳的固存能力越大。土壤粉粒复合体含量>黏粒复合体含量>砂砾复合体含量。砂粒复合体中有机碳含量增加1g/kg土壤有机碳含量将增加3.72 g/kg，黏粒复合体的相应增幅为3.27g/kg，黏粒是土壤有机碳固存的主要部分。仅施氮肥或氮磷配施显著降低0-20cm和20-40cm土壤碳酸钙含量。土壤有机碳含量随着土壤碳酸含量增加而增加，碳酸钙可促进土壤团聚体的形成。土壤全钙对土壤有机碳、重组有机碳、轻组有机碳、稳結态腐殖质、稳結态胡敏酸、稳结态富啡酸和紧結态腐殖质有贡献。水溶态钙对提升土壤紧結态腐殖质有贡献。发表论文6篇，申报专利3项，授权1项，获软件著作权4项,研发固碳新技术2项，研制新产品2项。