生物质炭对土壤物理肥力的改良与微生物响应机制

Soil physical fertility is an important part of soil fertility，which affects soil moisture, solute transport, fertility and plant root stretching, determines the quality and productivity of soil. Soil pore space, as the important indicator of soil quality, plays an important role in agricultural production and environmental protection. The aims of this project are to explore the effects of biochar on the mechanism of promoting the formation and stability of soil aggregates and the soil porosity characteristics improvement. It will clarify the scientific principle of biochar addition to improve soil physical properties on the perspective of soil porosity, as well as the microorganism response mechanism of porosity characteristics. The stability of soil aggregates is studied, with the stability factors extraction. Nitrogen adsorption (NAI) and mercury intrusion porosimetry are applied to establish quantitative methods of soil pores space, and to explore the pore size distribution, volume, specific surface area and fractal dimension. The role of soil physical properties and key pore factors are collected to clarify the response mechanism of soil physical properties to changes in pore characteristics, revealing the mechanism of biochar on soil pore improvement scientifically. The coupling relationship between soil physical fertility and soil microbial population, community structure and functional genes is investigated, revealing the effects of biochar on soil microbial community diversity, so as to explore the response process of soil microbes to biochar improved soil properties.

土壤物理肥力是土壤肥力的重要方面，影响着土壤水分和溶质运移、养分和根系伸展等，能够决定土壤的质量和生产力，是衡量土壤质量的重要指标，在农业生产和环境保护领域具有重要的作用。围绕研究生物质炭对土壤团聚体形成和稳定性机制以及对土壤孔隙特性的改良，从土壤孔隙的角度阐明生物炭对土壤物理性质改良的科学原理，阐明微生物菌群结构变化对土壤物理特性的响应机制。研究土壤团聚体的稳定性，提取稳定性的因素；结合氮吸附和压汞法等技术手段，建立土壤孔隙的定量方法，探究生物质炭对土壤孔隙大小，体积，比表面积和分形维数等的作用，提取土壤物理特性和关键孔隙因子，阐明土壤物理性质对孔隙特征的变化的响应机制，科学揭示生物质炭对土壤孔隙改良的机制；探究土壤物理肥力与土壤中微生物数量、群落结构和功能基因等耦合关系，揭示生物质炭对土壤微生物群落多样性的影响，探究土壤微生物对生物质炭改良土壤性质的响应过程。

滩涂盐碱地是具有巨大开发潜力的重要土地资源，作为未来生产的储备用地具有重要意义，但其物理力学性能差等特点阻碍了其可持续利用。本研究通过田间试验研究了生物质炭对滩涂盐碱地土物理力学特性的影响。生物质炭施于滩涂盐碱地显著提高了土壤肥力，即有机碳、全氮、有效氮和有效磷等。与对照处理相比，生物质炭处理改善土壤性质，显著提高了土壤孔隙度和团聚体稳定性，降低了土壤盐度。提高了滩涂盐碱地的塑性指数，降低了土壤抗压强度和线性膨胀性能。生物质炭明显改变了土壤孔隙特征，从而重新构建离子淋滤通道。生物质炭处理对土壤盐度、肥力、物理力学性质和作物产量的影响巨大。因此，生物质炭通过改善土壤孔隙和结构，改善土壤耕性，降低盐胁迫，降低机械强度等方面改善了滩涂盐碱地。