长期培肥水稻土微结构特征及对施肥措施改变的响应

Soil structure records the migration process and varying information of soil materials, which reflects the level of soil quality and fertility. Long-term of fertilization application induces soil structure variation, so it is necessary to clear the microstructure varying mechanism of reddish paddy soil under different fertilization measurements and its’ responsiveness to the follow-up fertilization application. In the research, with the technic means of physical & chemical analysis, observation under optical microscope, mercury intrusion, CT scanning electron microscope, electron probe, image processing and so on, three kinds of reddish paddy soils with different fertilization application in a long-term site-specific field experiment since 1982, as well as in specific field experiments since fertilization measurement altered in 2012, will be utilized to research the variation laws of microstructure such as porosity, aggregates, microscope structure, micromorphology and their relationship, exploring internal relations among indices of soil organic matter and oxide, clay mineral, micro-domain chemical ingredient of electron probe, features of microstructure and so on, and revealing the response mechanism of paddy soil microstructure to long-term different fertilization application. Meanwhile, clearing the paddy soil microstructure’s responsiveness to follow-up fertilization measurement by the plot experiment of the fertilization measurement altered. Furthermore, evaluating the relationship between soil quality and micromorphological diagnostic indices, and extracting micromorphological diagnostic indices of soil quality.

土壤结构记录土壤物质变化、迁移过程信息，反映土壤质量和肥力水平的高低。长期不同施肥后土壤结构发生改变，需进一步明确土壤微结构对不同施肥措施的应变机理及其对后续施肥变化的响应。本项目借助一起始于1982年的长期定位试验（该定位试验于2012年针对部分施肥处理已进行适当变更），以施肥措施变更/未变更的红壤性水稻土为研究对象，通过理化分析、镜下观察、土壤孔隙压汞、CT扫描和电子探针及图像处理等技术手段，采用相关分析、通径分析等方法，研究不同施肥措施下长期培肥水稻土理化特性、孔隙、团聚体、微形态等的变化特征及其相互关系；探究土壤有机质及组成、氧化物形态与数量、粘土矿物、电子探针微区化学成分等指标与微结构的内在联系；揭示长期培肥水稻土微结构对施肥措施的应变机理及其对后续施肥措施的变化响应；评价土壤质量与土壤特征微形态诊断指标的关系，为凝炼土壤质量微形态诊断指标提供依据。

土壤结构记录土壤物质变化、迁移过程信息，反映土壤质量和肥力水平的高低。由于土壤结构内在复杂性及人类活动的扰乱，长期施肥及施肥措施改变后土壤结构的变化特征及其主要影响因素仍缺乏认识。本研究选择了我国南方广泛分布的红壤性水稻土开展了长期定位及室内分析试验；在传统理化及团聚体分析的基础上，应用同步辐射显微CT和工业CT技术及压汞法研究了长期施肥及增减施有机肥后红壤性水稻土及团聚体孔隙结构、团聚体分布及其稳定性的变化特征；采用相关及聚类方法研究了红壤性水稻土及其团聚体孔隙结构、团聚体稳定性与有机碳及其组分、铁铝氧化的相互关系；通过结构方程模型明确了红壤性水稻土、团聚体的孔隙结构、有机碳和稳定性主要影响因素。结果表明长期施用有机肥的红壤性水稻土>0.25mm团聚体数量、团聚体稳定性、总孔隙度、主要孔径绝对孔隙度、分形维数等均高于长期使用化肥的处理；增施有机肥提高土壤>0.25mm团聚体数量、团聚体稳定性、团聚体总孔隙度及改善孔隙结构参数，优化团聚体孔隙结构，减施有机肥则土壤大团聚体及其稳定性降低、孔隙结构破坏。影响红壤性水稻土孔隙结构、团聚体及其稳定性以及团聚体孔隙结构的主要影响因素为有机碳及其组分。