引用本文:胡 瑾,慈 恩,王术芳,连茂山,翁昊璐,陈 林.重庆市更新统沉积物发育土壤的特性及分类[J].土壤学报,2020,57(2):273-283. DOI:10.11766/trxb201812210567
HU Jin,CI En,WANG Shufang,LIAN Maoshan,WENG Haolu,CHEN Lin.Genetic Characteristics and Classification of Soil Derived from Pleistocene Sediments under Cultivation in Chongqing[J].Acta Pedologica Sinica,2020,57(2):273-283. DOI:10.11766/trxb201812210567
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重庆市更新统沉积物发育土壤的特性及分类
胡 瑾, 慈 恩, 王术芳, 连茂山, 翁昊璐, 陈 林
西南大学资源环境学院
摘要:
选取重庆市境内分别由夹卵石黄色黏土(PC)、黄色黏土(YC)、红色黏土(RC)等更新统沉积物发育的6个典型旱地和水田土壤剖面为研究对象,探讨其土壤特性及系统分类归属。结果表明,PC发育的旱地土壤富含砾石且无铁锰斑纹,YC发育的旱地土壤不含砾石但有铁锰斑纹,RC发育的旱地土壤耕作层以下黏粒淀积明显。在PC和YC发育的水田土体内,上部土层的有机质累积明显且彩度较下部低,游离铁在下部土层有明显聚积,而母质为RC的水田土体内游离铁则迁移不明显。3个旱地土壤分别被划归为普通简育湿润雏形土、普通铁质湿润雏形土和红色铁质湿润淋溶土3个亚类,3个水田土壤则分别被划归为普通铁聚水耕人为土和普通简育水耕人为土2个亚类,共可建立6个土族和6个土系。YC发育的普通铁质湿润雏形土有铁锰斑纹存在,这是古水文条件的反映,现已完全脱离地下水的影响,故不再具有潮湿土壤水分状况;沉积物特征、区域气候等会影响旱地土体内黏粒的淋溶淀积,进而影响其土纲划分;水耕活动使更新统沉积物发育的雏形土和淋溶土演变为水耕人为土;地块筛选、坡改梯、拣拾等人为活动会显著减少PC发育的水田土体内砾石含量,影响其土族控制层段的颗粒大小级别判定。
关键词:  更新统沉积物  耕作条件  土壤特性  土壤系统分类  重庆
基金项目:国家科技基础性工作专项(2014FY110200)、中央高校基本科研业务费专项(XDJK2017B027)和西南大学科技创新“光炯”培育项目(2016001)
Genetic Characteristics and Classification of Soil Derived from Pleistocene Sediments under Cultivation in Chongqing
HU Jin, CI En, WANG Shufang, LIAN Maoshan, WENG Haolu, CHEN Lin
College of Resources and Environment, Southwest University
Abstract:
【Objective】It is of great significance to explore genetic characteristics and evolution laws of the soils derived from Pleistocene sediments to the study of geological evolution and ancient climate change and the management of the soil resources. Chongqing is a region dominated by mountains and hills, and hence known as “Mountain City”, where the soil layer is thin, except for the soils derived from Pleistocene sediments, which are often quite thick in soil layer and hence high in land utilization rate, so it is the important agricultural resource of Chongqing. However, so far little has been reported on genetic characteristics and classification of the soils and effects of cultivation on evolution of their properties. Therefore, this paper addressed the issue in an attempt to promote development of quantitative classification of the soils, to provide certain theoretic bases and important ideas for rational utilization of the soils, relative to soil type. 【Method】Field soil surveys were conducted to specify six soil profiles, 3 upland soils and 3 paddy soils, derived from Pleistocene sediments of pebble-mixed yellow clay (PC), yellow clay (YC) and red clay (RC), of which soil morphological characteristics were obtained through investigations of their soil-forming environments. PC and YC (commonly known as old alluvial sediments) are mainly distributed on the high terraces on both sides of the Jialing River and its main tributaries, and RC mainly on the karst plains and some valleys in Xiushan County. Soil samples were collected from the profiles by horizon for analysis of physico-chemical properties. Based on the comparative analysis, genetic characteristics and classification of the soils relative to cultivation mode were discussed, and diagnostic horizons and diagnostic characteristics of the soils were determined, and the soils were attributed and named in CST level by level in the light of the “Chinese Soil Taxonomy (3rd ed.)”. 【Result】The upland soil derived from PC was found to have a lot of gravels but no iron-manganese speckles or stripes, while that derived from YC was found to be in a reverse condition and that derived from RC to have apparent clay deposition right beneath the plow layer. In the profiles of paddy soils derived from PC and YC, organic matter accumulation was obvious in the upper part, while iron oxide accumulation was in the lower part, so the upper part was lower the lower part in chroma. However in the paddy soil derived from RC, migration of iron oxide was not as obvious. The 3 upland soils were sorted into 3 subgroups, i.e. Typic Hapli-Udic Cambosols, Typic Ferri- Udic Cambosols and Red Ferri -Udic Argosols, and further into 3 soil families, i.e. Coarse bone loamy silica non-acid thermic -Typic Hapli-Udic Cambosols,Clay loamy silica mixture non-acid thermic - Typic Ferri-Udic Cambosols and Heavy clayey illitic mixture acid thermic - Red Ferri - Udic Argosols, separately. The 3 paddy soils were sorted into 2 subgroups, i.e. Typic Fe-accumuli- Stagnic Anthrosols and Typic Hapli- Stagnic Anthrosols, and further into 3 soil families, i.e. Clay loamy silica mixture non-acid thermic - Typic Fe-accumuli - Stagnic Anthrosols, Clayey illitic mixture non-acid thermic - Typic Fe - accumuli - Stagnic Anthrosols and Clayey kaolinitic non-acid thermic - Typic Hapli - Stagnic Anthrosols, separately. The six soils formed 6 soil series in total. 【Conclusion】The soils derived from YC have iron-manganese speckles or stripes, which are reflections of paleo-hydrological conditions, but now they are completely free from the influence of groundwater and no longer were the aquic soil moisture regime. The characteristics of sediments and regional climate do have some impact on clay deposition in the upland soils, thus affecting their classification on the soil order level. Long-term paddy cultivation would transform Cambosols and Argosols derived from Pleistocene sediments into Stagnic Anthrosols. Artificial activities, such as field screening, changing slopes into terraces, gathering pebbles et al, would reduce gravel content in the paddy soil derived from PC, which would in turn influence particle-size fractionation of the soil layers controlled by soil family.
Key words:  Pleistocene Sediments  Cultivation conditions  Genetic Characteristics  Chinese soil taxonomy  Chongqing