探地雷达技术探测土壤特性的研究进展

总结了探地雷达技术(Ground Penetrating Radar,简称GPR)使用反射波、地波、反射系数、全波形反演和早期信号分析进行土壤特性研究的方法,在详细介绍基本原理的基础上,通过分析近年来的研究实例展示GPR探测土壤特性的能力和局限性:基于信号速度的分析方法应用广泛,数据获取和处理简单,但结果具有主观性,受...     

核酸分析方法在土壤微生物多样性研究中的应用

土壤微生物多样性一般包括微生物分类群的多样性、遗传(基因)多样性、生态特征多样性和功能多样性。传统的分离培养方法和土壤微生物的生化研究手段具有一定的局限性,核酸分析方法为土壤微生物多样性研究注入了新活力。本文主要综述了近年来国内外研究土壤微生物多样性所采用的核酸提取方法及核酸分析方法。重点阐述了基于PCR的分子指纹技术、核酸杂交技术、基因芯片等核酸分析方法的原理、优缺点和应用。各种土壤微生物多样性研究方法的综合应用可扬长避短,起到相互补充的作用,从而能够提供更加丰富而准确的土壤微生物群落结构及种群丰度变化等方面的信息,也将成为这一领域今后的发展趋势。     

土壤特性空间变异研究进展

对土壤特性空间变异的影响因素作了扼要分析 ;对土壤特性空间变异研究方法的发展概况作了初步讨论 ,并对土壤特性空间变异定量研究中涉及的主要分析方法及其参数作了初步介绍 ;对土壤养分空间变异定量研究的进展作了简要回顾     

Determining weathering rates of soils in China

As an important parameter for critical load calculation and soil acidification simulation, weathering rates of soils in China were studied using different methods of calculation. The approaches used were the mass balance approach, the soil mineralogical classification, the total analysis correlation, the PROFILE model, the MAGIC model and a simulated leaching experiment. Since chemical weathering of secondary minerals usually plays a much more important role in neutralizing the long-term acidification of soils in China than that of parent material, soil mineralogy rather than parent rock/material type, which is regarded as the most suitable factor representing weathering rates in Europe, should be adopted as the basis for soil classification. The weathering rate assigned to each soil should also be corrected when the effect of temperature is considered. Due to the variation in experimental conditions, the weathering rates of soils from laboratory experiment may be difficult to compare with field determined rates, and should be adjusted by pH and percolation rate. The comparison of various methods in this study shows that the weathering rates of soils estimated by the PROFILE model coincide well with those from other independent methods such as the dynamic modeling by MAGIC and the modified leaching experiment. The weathering rates were very low (usually lower than 1.0 kEq·ha⁻¹·year⁻¹) for Allites (including Latosol, Lateritic Red Earth, Red Earth, Yellow Earth and Yellow-Brown Earth) in south China and Silalsols (consisting of Dark Brown Forest Soil, Black Soil and Podzolic Soil) in northeast China, and very high for Alpine Soils, Desert Soils and Pedocals in west China. The content of weatherable minerals in soil is the most important factor in determining the spatial distribution of weathering rate in China, while the difference in temperature may be the reason why the weathering rate of soil in northeast China was lower than that in southeast China.     

黄土高原风沙区综合治理关键措施组合模式

通过对黄土高原风沙区已治理典型小流域水土保持治理措施的总结 ,选择基础资料比较详实的典型区 ,从土壤侵蚀、治理目标、关键措施及其相互之间关系等方面进行典型调查分析比较和效益评估 ,探讨了水土保持综合治理关键措施与组合方案。目前 ,在西部大开发中 ,风沙区的生态环境势必要优先考虑 ,统筹安排。否则不仅西部大开发难以顺利进行 ,也将会直接影响到东部地区经济的持续、稳定发展和人民生活质量的进一步提高。研究风沙区综合治理对实施以减沙治沙、恢复重建生态环境为目的的水土保持生态环境建设具有十分重要的意义。     

黄土高原风沙区综合治理关键措施组合模式

通过对黄土高原风沙区已治理典型小流域水土保持治理措施的总结,选择基础资料比较详实的典型区,从土壤侵蚀、治理目标、关键措施及其相互之间关系等方面进行典型调查分析比较和效益评估,探讨了水土保持综合治理关键措施与组合方案。目前,在西部大开发中,风沙区的生态环境势必要优先考虑,统筹安排。否则不仅西部大开发难以顺利进行,也将会直接影响到东部地区经济的持续、稳定发展和人民生活质量的进一步提高。研究风沙区综合治理对实施以减沙治沙、恢复重建生态环境为目的的水土保持生态环境建设具有十分重要的意义。     

Soil Bulk Density Estimation Methods: A Review

Measurement of soil bulk density is important for understanding the physical, chemical, and biological properties of soil. Accurate and rapid soil bulk density measurement techniques play a significant role in agricultural experimental research. This review is a comprehensive summary of existing measurement methods and evaluates their advantages, disadvantages, potential sources of error, and directions for future development. These techniques can be broadly categorised as direct and indirect methods. Direct methods include core, clod, and excavation sampling, whereas indirect methods include the radiation and regression approaches. The core method is most widely used, but it is time consuming and difficult to use for sampling multiple soil depths. The size of the coring cylinder used, operator experience, sampling depth, and in-situ soil moisture content significantly affect its accuracy. The clod method is suitable for use with heavy clay soils, and its accuracy is dependent on equipment calibration, drying time, and operator experience, but the process is complicated and time consuming. Excavation techniques are most commonly used to evaluate the bulk density of forest soils, but have major limitations as they cannot be used in soils with large pores and their measurement accuracy is strongly influenced by soil texture and the type of analysis selected. The indirect methods appear to have greater accuracy than direct approaches, but have higher costs, are more complex, and require greater operator experience. One such approach uses gamma radiation, and its accuracy is strongly influenced by soil depth. Regression methods are economical as they can make indirect measurements, but these depend on good, quality data of soil texture and organic matter content and geographical and climatic properties. Also, like most of the other approaches, its accuracy decreases with sampling depth.     

地下水浅埋条件下包气带水和溶质运移数值模拟研究述评

地下水浅埋条件下包气带水和溶质运移规律是解决土壤盐渍化、地下水污染等环境与生态问题的基本理论基础,基于多孔介质水和溶质运移基本方程的数值模型是研究包气带物质运移的重要手段。通过深入分析土壤水和地下水之间的相互关系,强调在地下水埋深小于其极限埋深的情况下应把地下水作用耦合到包气带水和溶质运移模型中。该文概括总结了现有研究把地下水作用与土壤水模型相耦合的方法,并分析了各种方法的优缺点。在回顾现有土壤水分运动参数和溶质运移参数确定方法的基础上,归纳了包气带水和溶质运移模型从“点”尺度向“田块”尺度扩展的途径,随机方法仍将是今后的研究热点,并有望应用于实践。     

A critical review of current methods in earthworm ecology: From individuals to populations

Earthworms play an important role in the functioning of many terrestrial ecosystems, and while their importance is frequently acknowledged significant challenges still remain in determining their operant roles within the soil. This lack of knowledge becomes increasingly important as the spatial scale of analysis increases from individuals to populations within the landscape. To effectively develop understanding, research techniques must be able to determine the effects that earthworms have on the soil system, as well as to establish how many and which species are present. A range of techniques are required to facilitate meaningful analysis from the micro-scale within a soil profile (e.g. drilosphere effects) to a field scale or landscape scale. Furthermore, an additional framework of understanding is required to investigate the role of earthworms in the biogeochemical cycles.By critically evaluating recent advances in methods and data analysis techniques in three areas of earthworm research we highlight that combinations of common approaches often offer the most significant insights into the functional roles of earthworms within a soil system. Through particular reference to earthworm sampling and identification, biochemical functions and persistent pollutant ecotoxicology of temperate ecosystems we emphasise how a range of investigation methods can be a hindrance to developing a whole-system level understanding. The complex and diverse nature of soil systems means that a traditional compartmentalised approach studying single species using a single research technique is no longer sufficient to gain further insights into the earthworm contribution to ecosystem goods and services delivered at the whole landscape scale. The integration of technologically advanced methods in combination with systems based modelling will be critical to develop landscape scale understanding of the functions of earthworms as individuals and as populations within in their ecosystems.     

Erosion modelling approach to simulate the effect of land management options on soil loss by considering catenary soil development and farmers perception

The prevention of soil erosion is one of the most essential requirements for sustainable agriculture in developing countries. In recent years it is widely recognized that more site‐specific approaches are needed to assess variations in erosion susceptibility in order to select the most suitable land management methods for individual hillslope sections. This study quantifies the influence of different land management methods on soil erosion by modelling soil loss for individual soil‐landscape units on a hillslope in Southern Uganda. The research combines a soil erosion modelling approach using the physically based Water Erosion Prediction Project (WEPP)‐model with catenary soil development along hillslopes. Additionally, farmers' perceptions of soil erosion and sedimentation are considered in a hillslope mapping approach. The detailed soil survey confirmed a well‐developed catenary soil sequence along the hillslope and the participatory hillslope mapping exercise proved that farmers can distinguish natural soil property changes using their local knowledge. WEPP‐model simulations show that differences in soil properties, related to the topography along the hillslope, have a significant impact on total soil loss. Shoulder and backslope positions with steeper slope gradients were most sensitive to changes in land management. Furthermore, soil conservation techniques such as residue management and contouring could reduce soil erosion by up to 70 percent on erosion‐sensitive slope sections compared to that under tillage practices presently used at the study site. The calibrated model may be used as a tool to provide quantitative information to farmers regarding more site‐specific land management options. Copyright © 2008 John Wiley & Sons, Ltd.     

Modern approaches to remediation of heavy metal polluted soils: A review

The main principles and approaches to remediation of in situ polluted soils aimed at the removal or control of heavy metals (washing, stabilization, phytoremediation, and natural restoration) are analyzed. The prospects of gentle methods of stabilization oriented at the reduction of the mobility and biological availability of heavy metals due to the processes of adsorption, ionic exchange, and precipitation are emphasized. The use of sorbents and the traditional application of liming and phosphates to fix metal pollutants in soils is considered. The necessary conditions for successful soil remediation are the assessment of its economic efficiency, the analysis of the ecological risks, and confirming the achievement of the planned purposes related to the content of available metals in the soils.     

Molecular profiling of soil animal diversity in natural ecosystems: Incongruence of molecular and morphological results

A major problem facing ecologists is obtaining a complete picture of the highly complex soil community. While DNA-based methods are routinely used to assess prokaryote community structure and diversity in soil, approaches for measuring the total faunal community are not yet available. This is due to difficulties such as designing primers specific to a range of soil animals while excluding other eukaryotes. Instead, scientists use laborious and specialized taxonomic methods for extracting and identifying soil fauna. We examined this problem using DNA sequencing to profile soil animal diversity across two Alaskan ecosystems and compare the results with morphological analyses. Of 5267 sequences, representing 549 operational taxonomic units (OTU), only 18 OTUs were common to both sites. Representatives included 8 phyla, dominated by arthropods and nematodes. This is the most comprehensive molecular analysis of soil fauna to date, and provides a tool to rapidly assess a missing component of soil biodiversity.     

Developments in soil microbiology since the mid 1960s

Since the 1960s, soil microbiology underwent major changes in methods and approaches and this review focuses on the developments in some selected aspects of soil microbiology. Research in cell numbers of specific bacterial and fungal groups was replaced by a focus on biochemical processes including soil enzyme activities, and flux measurements of carbon and nutrients. Ecologists focused on soil microbial pools whereas soil microbial biomass as an important source and sink of nutrients were recognized in agriculture. Soil microbiologists started to use structural components like phospholipid fatty acids for quantification of specific microbial groups without the need to cultivate them. In the last decade, molecular approaches allowed new insights through the analysis of soil extract DNA showing an unexpected diversity of genomes in soil. At the end of the review a brief outlook is given on the future of soil microbiology which ranges from in situ identification of bacteria, to routine assays of microbial communities by microarray technology.     

New trends in biochar pyrolysis and modification strategies: feedstock,pyrolysis conditions,sustainability concerns and implications for soil amendment

As a waste-derived soil amendment with a long history, biochar has received extensive attention for its capability to improve soil fertility/health; remove or immobilize contaminants in soil, water and air; and mitigate climate change. With the aim of producing engineered biochars with excellent performances, new trends in biochar pyrolytic production and modification strategies have emerged. This review critically summarizes novel pyrolysis methods (e.g., microwave-assisted pyrolysis, co-pyrolysis and wet pyrolysis) and modification approaches (e.g., mineral modification, photocatalytic modification, electrochemical modification) with a focus on (a) the mechanisms involved in environmental remediation processes including soil immobilization, contaminant adsorption and catalytic oxidation; (b) effects of feedstock and pyrolysis conditions on physicochemical properties; (c) sustainability considerations in novel modification and pyrolysis strategies; and (d) the feasibility of extrapolating the results from wastewater treatment to soil remediation. It is argued that in order to achieve the maximum net environmental benefits, ‘greener’ modification methods are warranted, and the risks associated with pyrolysis of contaminated feedstock in soil amendment and contaminant sorption can be minimized through various novel approaches (e.g., co-pyrolysis). Furthermore, novel pyrolysis methods can be combined with emerging modification strategies to synthesize more ‘effective’ biochars. Considering the similar aims of modification (e.g., increase surface area, introduce oxygen-containing functional groups, increase aromaticity), the applicability of several novel approaches could in future can be expanded from contaminant adsorption/degradation in aqueous media to soil remediation/fertility improvement.     

Development and use of soil productivity ratings in the United States

This paper provides historical documentation of major U.S. efforts to develop numerical ratings of soil productivity. Nearly all of these efforts stemmed from needs to compare different soils objectively for purposes of agricultural land use planning and the equalization of land values and tax assessments.Several approaches are described, including U.S.D.A. work following World War I, ratings based solely on crop yield data, Storie's (1933, 1937, 1976) multiplicative factor approaches and the variations that evolved from them, and “Soil property systems” that add, rather than multiply, effects of separate factors. Taken together, these various approaches highlight a large number of soil properties, weather conditions, and crop yield data that need to be considered to develop ratings of soil productivity. They illustrate a variety of techniques for evaluating the effects of soil properties quantitatively and for combining soil factor values into overall soil ratings. Each approach has certain advantages and limitations, and these are discussed throughout. The collective experiences with the development and use of productivity ratings cover a diversity of soil and climatic conditions throughout the United States.     

水土保持生态效益评价方法探讨

水土保持生态效益的计算与评价是水土保持科学研究的重要内容。根据水土保持项目实施后可能引起的区域生态要素变化的实际,探讨了土壤理化性质、水质、林草植被覆盖度和小气候变化的计算方法与评价方法。     

Pedodiversity and Its Significance in the Context of Modern Soil Geography

Methodological basics of the study and quantitative assessment of pedodiversity are discussed. It is shown that the application of various indices and models of pedodiversity can be feasible for solving three major issues in pedology: a comparative geographical analysis of different territories, a comparative historical analysis of soil development in the course of landscape evolution, and the analysis of relationships between biodiversity and pedodiversity. Analogous geographic concepts of geodiversity and landscape diversity are also discussed. Certain limitations in the use of quantitative estimates of pedodiversity related to their linkage to the particular soil classification systems and with the initial soil maps are considered. Problems of the interpretation of the results of pedodiversity assessments are emphasized. It is shown that scientific explanations of biodiversity cannot be adequately applied in soil studies. Promising directions of further studies of pedodiversity are outlined. They include the assessment of the functional diversity of soils on the basis of data on their properties, integration with geostatistical methods of evaluation of soil variability, and assessment of pedodiversity on different scales.     

基于数据同化的土壤水力参数反演方法：研究进展与展望

土壤水力参数及其非均质性刻画关乎到诸多土壤与地下水等领域的量化模拟研究问题。受限于时间和采样成本，传统的直接测定方法并不能很好地解决这个问题。随着物联网技术的发展，与土壤水运动有关的一些状态表征量（如含水量和水头）已经能够通过传感器实时获得。如何充分融合这些观测数据信息，反演出土壤水力参数是当前的一个研究热点。数据同化方法能够通过融合观测数据与模型预测值信息，实现对模型参数的反演估计。本文系统分析了土壤水力参数不确定性的来源及测定方法，阐述了常用数据同化方法的基础理论及其在土壤水力参数反演方面的应用，并从计算效率和反演精度两方面着重论述了数据同化方法的最新前沿进展，最后探讨了数据同化方法未来的发展方向。研究表明：数据同化方法能够突破传统测定方法的限制，用于土壤水力参数及其非均质性刻画。尽管如此，由于土壤非饱和流模型的强非线性以及原位观测数据的相对稀缺性等问题的存在，当前数据同化方法的计算效率和反演精度还有待进一步提升。未来可从发展监督式降维方法、多源多尺度数据融合以及耦合物理规律的机器学习等方面深化土壤水力参数反演方法研究，这有利于农业土水管理、污染防治和修复等工作的合理开展。     

Perspectives from the Fritz‐Scheffer Awardee 2017. How mucilage affects soil hydraulic dynamics#

Mucilage is a hydrogel exuded at root tips, which can hold large amounts of water but turns hydrophobic once dried. It is very challenging to understand the interplay of these opposite mechanisms and to incorporated them into hydraulic soil models. My summary of experimental and modelling approaches and observations at various scales is meant to help improving soil–plant water dynamic models and may also be helpful when water dynamics need to be considered in biogeochemical rhizosphere models.