摘要
为探究岩溶土壤CEC含量、机械组成与土壤矿物类型的关系,在湖南省典型岩溶区通过野外调查、挖掘、采集与描述石灰岩风化物母质发育的32个土壤剖面,室内分析146个样品的土壤理化性状,为岩溶土壤发育类型鉴定及改土培肥、生态修复奠定基础。结果表明:(1)湖南典型岩溶土壤CEC含量介于6.99~36.03 cmol·kg^(-1),土壤保肥能力中等偏强;土壤机械组成以粉粒、黏粒为主,质地黏重,通透性较差。(2)研究区岩溶土壤的主要矿物类型为:硅质混合型、伊利石混合型、高岭石型、高岭石混合型、混合型。五种矿物类型土壤均为酸性土壤,不同矿物类型土壤的pH、容重差异较小,但有机质含量差异较大;混合型土壤砂粒含量最高,硅质混合型土壤粉粒含量最高,高岭石土壤黏粒含量最高;CEC与ECEC含量在伊利石混合型土壤中最多,在混合型土壤中含量最少。(3)土壤CEC与粉粒含量呈极显著负相关关系,与黏粒含量呈极显著正相关关系(P<0.01),土壤粉粒含量的降低或黏粒含量的增加均可显著提高阳离子交换量值。土壤ECEC与粉粒、黏粒均无显著相关性,但其与土壤pH、有机质含量以及交换性Ca^(2+)、交换性Mg^(2+)均呈极显著正相关(P<0.01)。土壤CEC与矿物类型无相关性,而ECEC与矿物类型呈极显著负相关(P<0.01)。典型岩溶区不同发育程度的土壤可以通过调节土壤黏粒与粉粒含量的比例来改善土壤质地,增加土壤肥力。
In this study,a total of 146 profile samples were collected from 32 soil profile sampling sites in nine towns and cities in typical karst areas of Hunan Province.The physical and chemical properties of soil were analyzed through field investigation,excavation,and collection and description of soil profiles of limestone weathering parent materials.The relationships among soil CEC contents,mechanical compositions,and soil mineral types were also explored.The research findings laid a foundation for modification,fertilization and ecological restoration of karst soil.According to the Technical Specifications for Soil Analysis,the determination of soil physicochemical properties was conducted as follows:the soil pH values were measured by potentiometry.Both soil organic matters and total nitrogen contents in soil were determined by potassium dichromate heating method.Soil bulk density was measured by cutting ring method,while total phosphorus was assessed through the digestion-Mo-Sb anti-spectrophotometric method.Total potassium was analyzed via flame atomic absorption spectrophotometry.Exchangeable calcium and magnesium were quantified by EDTA titration method,and exchangeable sodium and potassium were also measued by flame atomic absorption spectrophotometry.The composition of soil particles was determined by pipette method,and the particle fraction was classified based on the system of United States(2.00–0.05 mm for sand,0.050–0.002 mm for silt,and<0.002 mm for clay).Types of clay minerals were determined by X-Ray diffraction.The cation exchange capacity(CEC)was determined by ammonium acetate centrifugal exchange method.The effective cation exchange capacity(ECEC)was calculated in the following formula:[cmol·kg−1]=H++Al^(3+)(⅓Al^(3+))+total extractability base.The results shows as follows.(1)The CEC contents of typical karst soil in Hunan ranged between 2.71–13.9 cmol·kg^(-1),with an average value of 16.70±5.62 cmol·kg^(-1).The sample values exhibited considerable variability.The average soil ECEC was 8.86±3.75 cmol·kg^(-1),sigificantly lower than soil CEC.The particulate composition of soil was mainly silt and clay,resulting in a heavy texture and poor permeability in the study area.Based on the American grading method for soil fertilizer retention capacity combined with the measurement data,it was observed that the soil fertilizer retention capacity in the study area predominantly fell within the medium to strong levels,but the soil fertilizer capacity was inadequate.(2)The particulate compositions of soil followed a trend of clay>silt>sand,encompassing nine texture types.The soil samples with clay texture constituted the largest proportion of 31.50%.This was followed by silty loam and silty clay loam,which accounted for 30.14%and 27.40%,respectively.The soil samples from the study area included five distinct mineral types:siliceous hybrid,illite hybrid,kaolinite,kaolinite hybrid and hybrid.The hybrid soil exhibited the highest sand content,while the siliceous hybrid had the highest content of powder silt,and the kaolinite hybrid contained the most clay.The CEC and ECEC contents were the highest in illite hybrid and lowest in hybrid soil.In general,the soil texture of the 146 samples was primarily clay,silty loam and silty clay loam,resulting in heavy and compact soil that adversely affected the air permeability and drainage of soil.(3)CEC exhibited a highly significant correlation with both silt and clay content,while showing no significant correlation with sand.Soil ECEC was not significantly correlated with any of the soil particles;however,it demonstrated a highly significant positive correlation with soil pH,organic matter content and total phosphorus content(P<0.01).Additionally,there was a significant positive correlation between ECEC and total potassium content,indicating a relationship between ECEC and the primary physicochemical properties of soil.This suggests that ECEC may influence the soil characteristics more effectively than CEC and could have a greater impact on soil fertility.(4)The primary exchangeable ions were Ca^(2+)and Mg^(2+),with soil CEC showing an extremely significant positive correlation with K^(+),Ca^(2+),and Mg^(2+)(P<0.01).Furthermore,soil ECEC was significantly positively correlated with K^(+),and extremely significantly positively correlated with Ca^(2+)and Mg^(2+)(P<0.01).Soil CEC was not correlated with mineral type,while ECEC was highly significantly negatively correlated with mineral type.The contents of Ca^(2+),Mg^(2+)and K^(+)in soil exchangeable salt-based ions also had an effect on the contents of CEC and ECEC in soils of different mineral types.In this study,soil CEC was found to be extremely significantly negatively correlated with silt contents.Conversely,there was a highly significant positive correlation with clay contents.This indicates that in karst soil,finer soil particles contribute to a more compact structure,which enhances soil cation exchange and improves soil fertilizer retention quality.However,the fertilizer environment can limit the nutrient cycle between soil and crops.By adjusting the proportions of silt and clay in soil,it is possible to increase the CEC value and enhance soil fertility.Although no significant correlation was observed between ECEC and soil particle compositions,ECEC was found to be significantly positively correlated with soil pH,soil organic matter contents,exchangeable Ca^(2+)and exchangeable Mg^(2+).Additionally,it exhibited a highly significant negative correlation with soil mineral types,which better reflects the synergistic effects of soil fertility conservation and nutrient supply.
作者
邢雨欣
袁红
吉香潼
段承龙
蒋军
刘单鹏
刘鹏
XING Yuxin;YUAN Hong;JI Xiangtong;DUAN Chenglong;JIANG Jun;LIU Shanpeng;LIU Peng(College of Resources,Hunan Agricultural University,Changsha,Hunan 410128,China;Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamics,MNR&GZAR,Guilin,Guangxi 541004)
出处
《中国岩溶》
CAS
CSCD
北大核心
2024年第5期1076-1087,共12页
Carsologica Sinica
基金
自然资源部、广西岩溶动力学重点实验室开放基金(KDL&Guangxi 202010)
科技部国家重点研发计划(2022YFD1700103-306)
湖南省教育厅重点项目(23A0185)。
关键词
阳离子交换量
土壤颗粒组成
石灰岩母质
cation exchange capacity
soil particle composition
limestone parent material
