堆垫层对关中塿土系统分类及土壤养分空间变异的影响

Lou soil was developed from Cinnamon soil affected by long-term human cumulic and farming cure, and it is the dominant agricultural soil and the main crop production area in Guanzhong area of Shaanxi province. The cumulic epipedon is not only the diagnostic basis for soil taxonomy, but also the indicator of soil fertility. While the spatial distribution of cumulic epipedon in the Lou soil area was never reported except limited records in some soil profiles. This has resulted in the divergence on soil taxonomy. And most of the research results on soil nutrients spatial distribution was contributed to land usage, climate and topography, while the essential indicator should contributed to the depth of the cumulic epipedon. In this project, Lou soil in Guanzhong area was taken as the research object, take the knowledge of pedogeography, soil taxonomy, soil physical and chemical as the basic theory, the cumulic epipedon spatial distribution and its effects on Lou soil taxonomy and soil nutrients distribution will be researched based on field observation, soil profile dig, sample collection, laboratory analysis, combined with GIS technology and mathematical methods. This project will focused on the effects of cumulic epipedon on soil taxonomy and establish the soil classification system of Lou soil. While we will reveal the effects of cumulic epipedon on soil nutrients distribution and will built the coupling relationship between cumulic epipedon and soil nutrients. Also soil quality evaluation indicators, cumulic epipedon included, will be selected and the soil quality will be evaluated and subarea will be divided in the Lou soil area. The results of this project will enrich the knowledge of soil genetic theory and provide useful theoretical methods for reasonable utilization of Lou soil in the future.

塿土是在褐土基础上长期施用土粪堆垫并经耕作熟化形成的，是关中地区主要耕种土壤和粮食产地。堆垫层既是塿土系统分类的主要诊断依据，也是塿土肥力水平的表征。目前对塿土分布区堆垫层的描述仅见于少数剖面记载，未见到堆垫层空间分布的报道，以致塿土的系统分类归属产生较大分歧；对塿土养分空间变异一般归结为土地利用、气候、地形等因素，而未能从堆垫层厚度的角度揭示养分空间变异的本质。项目以关中塿土为研究对象，根据土壤地理学、土壤分类学及土壤物理、化学理论，通过野外调查、剖面挖掘、样品采集、室内测试等手段，结合GIS及现代数学方法，研究塿土堆垫层空间分布状况，阐明堆垫层厚度对塿土系统分类归属的影响，建立塿土系统分类体系；揭示堆垫层厚度对塿土养分空间分布的影响，构建堆垫层厚度与土壤养分的耦合关系；建立堆垫层厚度在内的塿土质量评价指标体系，开展塿土质量评价，为现代土壤分类理论的完善及塿土科学合理利用提供理论基础。

塿土既是关中平原重要的农业土壤，也是土壤调查与分类的重要研究对象。其中堆垫层厚度对于塿土的肥力特征及土壤分类归属具有重要影响，本项目针对塿土堆垫层厚度空间部分不清楚，塿土系统分类归属不完善的问题，在关中塿土分布区布设5 km × 5 km 网格样点，调查了288个塿土剖面，分析了堆垫层厚度及其土壤养分的空间分异特征及其影响因素，开展了塿土土壤质量评价及利用分区，构建了塿土系统分类体系。结果表明塿土堆垫层厚度总体范围在14 -130 cm之间，平均厚度为55 cm；关中东部及西部相对较厚，中部较薄；土壤养分中西部高于东部，建立了包括塿土堆垫层在内的评价体系，塿土综合肥力水平范围在0.13-0.66之间，将塿土分布区划分为了东部厚堆垫低肥力区、中部宽平中肥力区和西部窄平高肥力区，其中养分含量和土壤综合质量依次升高。按照中国土壤系统分类检索标准，采集的18个典型剖面包含堆垫表层、黏化层、钙积层等9个诊断层和诊断特性，堆垫层厚度50cm以上的13个剖面被检索为人为土纲，堆垫层厚度在20- 50cm的4个剖面诊断为堆垫简育干润淋溶土，建立了9个土族和18个土系。研究结果为塿土资源的开发与合理利用提供基础，也为进一步完善中国土壤系统分类提供参考。