毛乌素沙地砒砂岩与沙复配农田的固沙效应及其微观机理

砒砂岩与沙复配成土及其工程化核心技术的提出与应用，为毛乌素沙地合理利用土地资源、科学推进生态建设提供了新的思路与技术支撑。前期研究对利用层面的技术问题给予了较多关注并取得显著进展，而在潜在风险层面特别是关于复配土壤的固沙效应及其微观机理的探索则相对薄弱。基于集沙仪、扫描电镜及激光粒度仪，结合野外定位试验和室内仪器观测，对毛乌素典型原状沙地及复配农田的输沙特征差异及其固沙微观机理进行探索。结果表明：（1）观测周期内，原状沙地输沙总量为4 951 g，远高于复配农田2 436 g的输沙总量，原状沙地更易受风蚀，而复配农田土壤起沙风速大、输沙量较小，具有明显的固沙效应；（2）扫描电镜图像显示，原状沙地土粒（沙粒）粗骨化、无粘结，而耕种两年的复配农田土壤中已出现团聚体；（3）激光粒度仪分析显示，原状沙地的粉、黏粒含量仅为2.74%，而复配农田这一比例增至15.12%；（4）复配土防风固沙效应的形成与粉粒和黏粒含量及土壤结构等紧密相关。鉴于复配农田输沙固沙能力的动态差异性和风力敏感性，进一步实施复配成土造田工程时，宜在复配农田主导风向的上风向区域及成片农田内适当布设具有防风功能的适生草类或灌木条带。

Sand-fixation Effect and Micro-mechanism of Remixing Soil by Pisha Sandstone and Sand in the Mu Us Sandy Land,China

As the core technology and engineering of remixing soil by Pisha sandstone and sand have been presented, there are new ideas and technology supports for rational utilization of land resources and the construction of ecological civilization in a scientific way in the Mu Us Sandy Land. More attention had been paid on technology problems of utilization in previous studies, and remarkable progress had been made. But there still need to strengthen the study of sand-fixation effect and micro-mechanism of remixing soil by Pisha sandstone and sand. This paper aims to exploring the sediment transport volume of typical sand in the Mu Us Sandy Land and remixing farmland and its micro-mechanism based on 8-directional sand collector, scanning electron microscope (SEM) and laser particle size analyzer (LPSA). The results show that: (1) During the whole observation period, the sediment transport volume of the remixing farmland of Pisha sandstone and original sand was 2 436 g, which was only a half of that of original sand (4 951 g). This indicated that the remixing farmland of Pisha sandstone and original sand has the function of sand-fixation. (2) SEM observation showed that soil aggregate began to emerge in the remixing artificial soil, while in the sandy soil, there was still no bond and soil aggregate and the sand particles were fragmental. (3) LPSA analysis showed that the silt content and clay content only accounted for 2.74% in sand, while this percentage increased to 15.12% in remixing artificial soil. So we can infer that the sand stabilization is closely related with soil structure and the silt and clay content in soil. According to the sand-fixing effects of compound soil by mixing sandstone and sand, suitable grass or shrub belt with windproof function should be constructed in the upper regions of dominant wind direction in the first three or four years of projects implementation.