免耕条件下植物和微生物来源碳组分区分及保护机制

A no tillage experiment was set in the Conservation Tillage Station of Chinese Academy of Sciences in black soil region. The soils are sampled in the treatments with different amount of stover mulch. The methods of physical and chemical fractionation combined with mid-infrared and 13C NMR spectroscopy are used to elucidate the turnover and fate of plant-derived organic matter as well as the spectral characteristics of the soil organic carbon. One of the biomarkers, neutral sugar, is used to indicate the effects of plant-derived carbon and the microbial-derived carbon on the quantity and components of soil organic carbon. Another biomarker, amino sugars are used to indicate the contribution of necromass residue-C to the soil organic carbon pool. Furthermore, the biomarker, lignin is used to clarify the process of plant-derived carbon accumulating in the soil carbon pool. The physical and chemical protection mechanisms of aggregates and particle-size fractions are considered to explore the stabilization process of plant- and microbial-derived carbon. The characterization of molecular carbon in bulk soil and physical fractions are analyzed by mid-infrared and 13C NMR spectroscopy to observe the change of carbon chemical fractions in no till system. This project will provide a theoretical support for soil organic carbon sequestration and transformation in no till system with stover mulch in black soil region.

东北地区施行表层秸秆覆盖的免耕耕作制度可有效遏制黑土退化，对秸秆资源利用及黑土地力提升具有重要意义。探索地表输入有机质的去向及转化过程、土壤有机碳组分变化规律及其稳定机制，是亟待解决的科学问题。采用土壤有机质的物理分级及化学分析技术，结合土壤有机碳红外光谱及13C NMR特征，研究土壤中植物来源碳的转化、去向及其对土壤有机碳组成特征的影响。利用生物标识物中性糖探索秸秆来源碳与微生物来源碳对土壤有机碳含量和组成的影响，利用氨基糖指示死亡微生物残体来源碳对土壤有机碳库的贡献；采用木质素指示植物来源碳被微生物分解及其在土壤中的累积过程，结合红外光谱及13C NMR技术研究土壤有机碳的分子结构组成特征；分析土壤物理分级组分（团聚体和颗粒组分）对不同来源有机碳的物理、化学保护机制，阐明植物来源碳经微生物转化最终形成稳定碳库的过程。本研究可为黑土可持续生产及高效管理提供理论支持。

东北地区施行表层秸秆覆盖的免耕耕作制度可有效遏制黑土退化，对秸秆资源利用及黑土地力提升具有重要意义。探索地表输入有机质的去向及转化过程、土壤有机碳组分变化规律及其稳定机制，是亟待解决的科学问题。采用土壤有机质的物理分级及化学分析技术，结合土壤有机碳红外光谱特征，土壤微生物及土壤动物的群落机构特征，研究土壤中植物来源碳的转化、去向及其对土壤有机碳组成特征的影响。结果表明，低量与高量秸秆还田对表层与中层易分解碳组分的影响较大，均提高了表层与中层多糖含量以及中层脂肪族碳组分含量。中量秸秆还田提高了深层土壤多糖组分含量。低量秸秆还田不利于深层土壤碳化学稳定性的维持，中量秸秆还田有利于深层土壤碳化学稳定性的提高，而高量秸秆还田有利于各层次土壤碳化学稳定性的维持。秸秆覆盖显著促进了土壤微生物的活性及土壤动物个体数量。研究明确了秸秆来源碳在土壤物理分级组分中的分布及其物理、化学保护机制，阐明了秸秆覆盖条件下土壤生物群落结构的组成及变化。本研究为黑土可持续生产及高效管理提供理论支持。