高产红壤性水稻土结构特征及其形成机制

The well-developed soil structure is necessary to the high productivity of rice paddy soil. However, structure characteristics of the high-yield paddy soil is unclear nor quantified. And the formation mechanisms of the structure are also unclear. This project addresses these questions on red paddy soil that widely spread in south China. Based on field investigation and long-term field experiments, undisturbed and bulk soil samples from the tillage layer and plow pan of the soil with different fertility will be collected. Micro-tomography (μ-CT) and (ultra-)micromorphological techniques will be employed to quantify the undisturbed structure of aggregates and cores. The relationship between soil structure and soil fertility will be analyzed. Then, a series of incubation experiments, including addition/removal of soil organic matter (SOM), addition/removal of iron oxides, with/without rice cultivation, will be conducted to study the effects of SOM, iron oxides, root, and clay on soil aggregation. Wetting-drying cycles and tillage regimes will also be involved in these experiments. During the incubation, samples will be collected and analyzed dynamically to investigate the formation processes of soil structure. Based on the above work, we aim to clarify and build the framework of the formation mechanisms of the structure of high-yield red paddy soil. This work will promote the simulation of soil processes, as well as provide the theory basis to improve soil structure.

良好的土壤结构是水稻高产的必要条件。然而，高肥力水稻土具有什么样的结构特征？这种结构是如何形成的？这两个问题我们仍不清楚。本研究选择我国南方广泛分布的红壤性水稻土，基于野外调查和长期定位试验，在传统理化分析、形态学和团聚体分析的基础上，应用显微CT技术和（超）微形态技术，研究高产红壤性水稻土结构特征，统计分析高产水稻土结构的共性特征。在此基础上，针对高产红壤性水稻土，结合长期定位试验和室内培养实验，研究有机质、氧化铁、粘粒、根系等因素对结构形成的影响，并结合干湿交替、田间耕作措施等研究水稻土结构形成的动态过程。最后综合以上工作，提出红壤性水稻土形成机制的理论框架。通过本研究，希望能初步回答上述两个问题，并为模拟土壤过程、有针对性地改良土壤结构提供理论依据。

良好的土壤结构是水稻高产的必要条件。但是由于土壤结构自身的复杂性以及水稻土强烈的动态变化，人们对于水稻生长所需要的土壤结构条件仍缺乏定量的、动态的认识。本研究主要关注水稻土的结构特征及其形成和动态变化。本研究选择我国南方广泛分布的红壤性水稻土，开展了野外调查采样、长期定位试验和室内培养试验；在传统理化分析、形态学和团聚体分析的基础上，应用显微 CT 技术研究了红壤性水稻土结构特征，应用土壤收缩模型模拟土壤结构动态。在土壤结构研究的基础上，探索了土壤结构与养分供应和水稻生长的关系。研究结果表明有机质对土壤结构形成具有重要作用，增施有机肥可以提高改良土壤结构；高肥力土壤孔隙度和大孔隙度高、结构稳定；大孔隙度提高有利于水稻生长；搅浆处理破坏土壤结构，不利于土壤养分的持续供应等。研究结果丰富了水稻土基础理论，同时为农业生产提供了理论参考。