首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
中国黑土地保护政策演进过程与特征的量化考察   总被引:1,自引:0,他引:1  
  目的  研究中国黑土地保护政策的演进特征和规律,为其更好地引领黑土地保护工作开展提供参考与依据。  方法  以政策过程理论为指导,基于政策文献计量法和内容分析法,使用1998 ~ 2021年期间出台的国家及各省市层面304份黑土地保护政策文献数据,提出了黑土地保护政策强度量化标准,对政策强度、数量、纵横结构进行分析。  结果  黑土地保护政策强度与政策数量不断上升且呈现出阶段性特征;政策颁布机构以农业农村部(含原农业部)、水利部居多,存在一定数量的多部门联合颁布政策;政策形式以“通知意见”为主,拥有党中央宏观指导方针;政策主题集中于保护目标、试点建设、技术模式方面;政策工具以命令控制型为主,其他类型工具使用次数有所增加;政策演进经历了萌芽探索、初步形成和深化发展三个阶段。  结论  中国黑土地保护政策不断优化,未来应以构建“数量、质量、生态、权益”四位一体的系统性保护体系为目标,推动黑土地保护法治化进程,结合“田长制”的深入推行,完善生态补偿机制,细化保护责任、过程管理、监督反馈,提升政策的可操作性。  相似文献   

2.
Amounts of phosphorus taken up by maize plants during 23 days from an Entisol, two Alfisols and an Ultisol from Nigeria, each with three histories of management, were related to the concentration of soil phosphorus extracted in 0.01 m CaCl2; but the relationships differed between kinds of management. Phosphorus in plants 51 days old was not related to concentration. Relationships of plant phosphorus with isotopically exchangeable phosphorus, and with phosphorus extracted from the soils by anion exchange resin, were poor in young plants but were good in the older plants, irrespective of field management. Amounts of phosphorus in the older plants were also well related to estimates of exchangeable phosphorus computed from P in solution and amounts of amorphous iron oxides extracted by ammonium oxalate from the soils, using equations derived in an earlier investigation with a larger group of soils. Thus estimates of exchangeable phosphorus made from simple measurements of the soil constituents that largely control it, and from extraction by resins, are potentially useful to indicate the ability of soils to supply phosphate to crops, and hence to guide fertilizer policies.  相似文献   

3.
Greenhouse gas emissions from farmed organic soils: a review   总被引:14,自引:0,他引:14  
Abstract. The large boreal peatland ecosystems sequester carbon and nitrogen from the atmosphere due to a low oxygen pressure in waterlogged peat. Consequently they are sinks for CO2 and strong emitters of CH4. Drainage and cultivation of peatlands allows oxygen to enter the soil, which initiates decomposition of the stored organic material, and in turn CO2 and N2O emissions increase while CH4 emissions decrease. Compared to undrained peat, draining of organic soils for agricultural purposes increases the emissions of greenhouse gases (CO2, CH4, and N2O) by roughly 1t CO2 equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural area, these soils contribute significantly to national greenhouse gas budgets. Consequently, farmed organic soils are potential targets for policy makers in search of socially acceptable and economically cost-efficient measures to mitigate climate gas emissions from agriculture. Despite a scarcity of knowledge about greenhouse gas emissions from these soils, this paper addresses the emissions and possible control of the three greenhouse gases by different managements of organic soils. More precise information is needed regarding the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be devised.  相似文献   

4.
The present study illustrates a framework to evaluate soil consumption in Mediterranean regions experiencing rapid urban growth. Results indicate that high-quality soils more suitable for agriculture and forestry were mostly consumed by urbanization especially in flat areas. The consumption of these soils was not concentrated in the first observation period (1948–1975) corresponding to the development of compact settlements, but increased significantly in the last period (1975–2010) mainly characterized by discontinuous and low-density urban expansion. The study underlines the urgent need to inform development policies and urban planning with an in-depth quantification of the soil resource base lost by urbanization.  相似文献   

5.
《Soil Use and Management》2018,34(1):134-146
It has long been realized that the conservation of soil capital and ecosystem services are of paramount importance, resulting in a growing case for a change in attitude and policymaking in respect of soils. Current UK and EU approaches are risk‐based and focused on measures to manage and remediate the adverse impact of current policies and practices directed at maximizing productivity and profit, rather than one of resource conservation. Increasing soil loss and degradation is evidence that current policy is not working and a new approach is needed. In the UK there is governmental ambition to progress towards natural capital‐led land use policies but, in the absence of a framework to determine the relative condition of the soil resource, the delivery of sustainable soil conservation policies will continue to be inhibited. Common Standards Monitoring (CSM ) is an established monitoring and management framework (based on ecosystem structure, function and process) and has been effectively deployed for almost two decades by the UK Government for the monitoring and reporting of key biological and earth science natural capital and ecosystem services from ‘field’ to local, regional and national levels to the European Commission. It is argued that a CSM for soils could be developed for the UK 's soil resources as well as for those elsewhere, and would be able to deliver a conservation rather than the current risk‐based approach. It is capable of accommodating the complexities and variation in soil types and functions and potentially being practical and cost‐effective in its implementation.  相似文献   

6.
Abstract. Knowledge of the stocks and the potential range of soil organic carbon (SOC) in various land–soil combinations is an important precursor to policies aimed at linking, for example, management of SOC to greenhouse gas emission controls. To investigate the factors controlling the percentage of SOC (%SOC) of soils in England and Wales, we made a multiple regression analysis of data for the 2448 arable and ley-arable sites in the 1980 England and Wales National Soil Inventory (NSI). Clay content, average annual precipitation and depth of topsoil explained 25.5% of the variation in %SOC, when calcareous and peaty soils and those susceptible to flooding were excluded. Using 'robust' statistics, 'indicative SOC management ranges' were estimated for different physiotopes, that is, landscape units for which the environmental factors governing %SOC are similar, namely soil clay content and precipitation. These ranges describe the expected %SOC range for an arable soil in a given physiotope. They have potential to support approximate targets for the %SOC of arable soils and for estimating upper and lower limits for sequestered soil carbon in arable systems.  相似文献   

7.
Little is known on the hydrological behavior of the volcanic ash soils, which are characterized by extremely high porosities and hydraulic conductivities. In this study the occurrence and hydrological effects of water repellency were investigated at a plot scale for different types of land use and volcanic soils in Mexican volcanic highlands from Michoacan, Mexico: [1] fir, pine and oak mixed forest soils developed from lavas, [2] soils developed from volcanic ashes and pyroclastic sediments under sparse fir, pine and oak forest and shrubland, [3] pine and oak forested soils developed from lavas and pyroclastic sediments, and [4] bare soils on recent ash sediments in plain surfaces. Soil water repellency was assessed using the water drop penetration time test and rainfall simulations were performed on circular plots (50 cm in diameter) during 30 min and at an intensity of 90 mm h− 1 in order to study the hydrological response of each area. The return period for storms with a similar intensity in the area is 10 years. The shape and depth of the wetting front after simulated rainfall was also analyzed. Soil water repellency showed a high variability among the different studied zones. Organic matter content, soil texture and acidity were the most important factors for developing hydrophobicity. A wide range of soil water repellency classes (hydrophilic to severely water-repellent soils) has been found in soils under dense fir, pine and oak mixed forests or shrubland, while inexistent or slight water repellency has been observed in soils under sparse forest or at bare ash-covered areas. At a plot scale, marked differences in the hydrological behavior of the studied land use and soil zones were observed after the rainfall simulations. Soil water repellency contributes to fast ponding and runoff generation during the first stages of rainstorms. Runoff was enhanced in water-repellent forested soils (average runoff coefficients between 15.7 and 19.9%), in contrast to hydrophilic or slightly water-repellent soils, where runoff rates were lower (between 1.0 and 11.7%). Shallow and irregular wetting fronts were observed at water-repellent zones, reducing the soil water storage capacity. The implications of soil water repellency in soil hydrology and erosion risk in the area shed light on the soil hydrology of the studied ecosystems, and can contribute to develop better management policies.  相似文献   

8.
Abstract. Soil protection policies are being developed in many countries, particularly those in the European Union where pan-national regulatory frameworks now exist. We report an analysis of a survey of the views of a wide range of stakeholders in the soil resource of Scotland, including representatives of rural and urban land users, public bodies and authorities, non-governmental environmental organizations, and soil scientists based in Scotland. The four soil issues considered of particular importance were soil pollution, soil erosion, loss of soils to development, and loss of biodiversity. Comments were strongly polarized, either strongly promoting issues or indicating lack of awareness, on a set of topics: the loss of valued soils, loss of archaeological sites, and changes in terrestrial carbon store. It is argued that an integrated approach is required to implement any future soil protection strategies, and that special attention should be paid to monitoring long-term changes and to provision of soil survey data from urban areas.  相似文献   

9.
中国农田土壤环境质量管理现状与展望   总被引:8,自引:1,他引:7  
农田土壤环境质量保护与管理是保障粮食安全和农业可持续发展的重要前提.近年来,随着我国社会经济的快速发展,农田土壤环境质量退化和土壤污染问题逐渐凸显.经过几十年的努力,我国目前基本形成以"土壤污染防治法"和"土壤污染防治行动计划"为核心政策,相关配套管理办法、标准和技术规范等为基础的土壤环境质量管理体系.本文简要梳理了我...  相似文献   

10.
The discovery in the early 1980s that soil microorganisms, and in particular the symbiotic bacteria Rhizobium, were highly sensitive to heavy metals initiated a new line of research. This has given us important insights into a range of topics: ecotoxicology, bioavailability of heavy metals, the role of soil biodiversity, and the existence of ‘keystone’ organisms. Concurrently, and particularly in Europe, the research led to new approaches to the protection of soils from pollution that take into account the many effects on soil microorganisms. To date these key findings have largely been ignored in the USA, although our results caused considerable controversy there. In the past decade there have been many advances in the ecotoxicological assessment of metals and their effects on soil organisms but major gaps in knowledge and theory remain with regard to how microorganisms are exposed and respond to metals in soils. In this brief review we emphasise the need for long-term experiments and basic research to forge this understanding and improve environmental protection policies.  相似文献   

11.
Emergence of policies dealing with concern over soil degradation and anthropogenic impacts to soil is likely to increase the requirement for assessment of soil quality and identification of soils at risk from degradation. An example is the proposed EU Soil Framework Directive, which features the identification of areas requiring protection from soil degradation. There have been some serious objections to such requirements on the grounds of resource and capital demands. To help to address these concerns, this work proposes a strategic set of indicators based on measured soil quality indicators. These can be used in screening locations to assess the likelihood of degradation and indicate areas for further detailed assessment. This will allow further emphasis to be placed on a smaller number of locations, which could lead to cost and resource efficiencies. Indicators have been used in the past in assessment of soil quality; they are parameters which can be measured and correspond to assessment criteria to measure and help monitor the status and changes. The study reviews the current state of soil quality assessment including methods and indicators that are used to collect data and approaches used to assess data to determine areas subject to soil degradation. Methods and practicalities for data collection and screening are discussed, including the need for further pilot testing and protocol development. Use of public data collection could allow more resource efficient protection of soils, in addition to benefits of public engagement, and raising awareness of the importance of soils and soil biodiversity. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

12.
The microelemental composition of volcanic soils of Kamchatka is specified by the composition of the volcanic ashes from which these soils are developed. It is found that the soils developing from acid and intermediate ashes are characterized by low contents of most of the studied microelements as compared with their clarke values in soils of the world. The background concentrations of microelements in the soils developed from intermediate ashes of Kamchatka are higher than those in the soils developed from acid pyroclastic deposits. Differences in the microelemental composition of the soils developed from different ashes are seen against the regional background specificity of the volcanic soils of Kamchatka. These soils are enriched in the elements typical of mafic magnetic rocks. In particular, this concerns Cu, Mn, Sc, V, and Ag; the concentrations of these elements in the soils of Kamchatka are higher than their average concentrations in soils of the world. This is related to the common geochemical properties of volcanic ashes in Kamchatka, whose composition reflects the geochemical specificity of the multistage volcanism on this peninsula.  相似文献   

13.
Technical, economic and institutional conditions are changing rapidly in Eastern Europe. the area has inherited a high level of chemical pollution of soil and water resources, leading to grave risks of chemical time bomb effects. With the current financial and manpower constraints and the general stress on the new economies of the subregion, any substantial environmental improvements reversing past trends will require considerable time, during which chemical pollutants will continue to accumulate in soils and waters. Special emphasis is given to diffuse and accelerated pollution from inappropriate or changed land uses. It is suggested on the basis of recent legislation on transboundary and national chemical pollution in Europe that national policies, priorities and legislation shoud be developed throughout Eastern Europe.  相似文献   

14.
J.G. Bockheim 《Geoderma》1980,24(1):45-69
Polar Desert soils in the Arctic (66° and 74°N latitude) are contrasted with Cold Desert soils in the Antarctic (77°S). The soils are derived from sandy-skeletal glacial drift and have not been influenced by cryoturbation. Pedogenic horizons are limited to a desert pavement (designated D) and to a weak B horizon in the oldest soils of both groups. Solum thickness increases with age in the two soil groups; however, because of a slightly greater amount of soil moisture, the increase in solum thickness is greater for Polar Desert soils. Soils of both groups often contain “dry” permafrost. The Polar Desert soils at 74°N and most of the Cold Desert soils are neutral to mildly alkaline and the Polar Desert soils at 66°N are strongly to medium acid. Although soluble salts increase with age in soils of both groups, the increase is more marked in the more arid Cold Desert soils. Results from this study and a survey of the literature show that sodium is the prevalent cation in water extracts of Cold Desert soils and in Polar Desert soils above ca. 80°N. Chloride is the major anion in Cold Desert soils in the McMurdo Sound vicinity and in noncalcareous Polar Desert soils. Ion ratios indicate that salts in these soils are contributed by marine aerosols. The soils examined contain less than 5% clay-size (< 2 μm) material. Mica, vermiculite and kaolinite are the predominant phyllosilicate minerals in the clay fractions of Polar Desert soils, and mica, vermiculite and montmorillonite are most abundant in Cold Desert soils. A scheme contrasting clay-mineral alteration in soils of the two groups is provided. In the Canadian system, the Cold Desert soils are Static Cryosols, and the Polar Desert soils are either. Static Cryosols or Dystric Brunisols. In the U.S. system, the soils are Pergelic Cryorthents. Suggestions are given to modify the U.S. system so as to better distinguish polar soils.  相似文献   

15.
The zonal soils in the south subtropical zone of Fujian are lateritic red soils.A type of dark clayey soils.which was historically defined as lateritic red soils,derived from weathering products of the basalts was indicated by the investigation results to be markedly different from lateritic red soils and could be classified as Typical Hapluderts.They are distributed as complex zones with the lateritic red soils.The vertisols in this region were considered as a type of lithogenic soils and the vertic characteristics delay and inhibit the soils from allitic processes and then formed an independent soil type.The vertisols have higher fertility and better agricultural production characters than the lateritic red soils.The different ways in utilizing and managing these soils according to their properties and fertility are also suggested.  相似文献   

16.
三峡库区土壤有机质区域分布及影响因素   总被引:6,自引:0,他引:6  
利用多目标地球化学调查方法,通过野外实地调查、大面积系统采集土壤表层、深层样品、测试分析和数理统计,探讨了三峡库区不同土壤类型深层和表层土壤中有机质含量分布特征。以紫色土为例探讨了不同分布高程、坡度和不同植被条件下对有机质含量的影响。结果表明:三峡库区土壤有机质含量总体上较低,均为矿质土壤。成土母质类型对土壤有机质含量影响明显,相同自然条件成土作用下,海相石灰岩母岩区的土壤有机质高于陆相砂、泥岩母岩区的土壤。在土地利用方式上,水耕模式有利于增加土壤有机质。地形高程、坡度对紫色土有机质分布影响明显,随着海拔高度的降低,紫色土有机质含量明显降低;随着地形坡度降低,土壤有机质明显升高。植被覆盖类型上,草丛区、阔叶林区有机质具有高于混交林区、灌丛区、针叶林区的趋势。紫色土有机质与P,S等元素呈极显著正相关,但与造岩矿物元素及母质来源的元素相关性差。  相似文献   

17.
Mineral-selective K release from soils by octodecylammonium- ions (nc = 18) nc18-releasable potassium was determined on soils of five different areas. nc18-releasable K is the potassium which is displaced by octodecylammonium ions (ODA). Because the main sources of this potassium are trioctahedral micas, it is called briefly biotite-K. The investigated soils are from different areas in Bavaria (loess and clay stone derived soils, alluvial soils); partly the locations are K fertilizer trials. Soils of known age are locations from the Niederrhein terraces (Holocene soils). In the 0.2–2 μm (coarse clay) and 2–6 μm (fine silt) fractions the biotite-K content lies between 12 and 40% of total K. At given fractionation the highest amounts of K were released from the coarse clay of the soils. In the loess soils rich in silt the biotite-K pool in the medium and coarse silt fractions was also considerable. Clay soils showing poor K supplying power (K fertilizer trials) in the field are characterized by very low biotite-K quantities in all silt fractions. In the Holocene soils the age of which varies between 4 000 and 8 000 years the ODA releaseable values are greater than in the loess soils. In all fractions of the young Holocene soils the released K is greater than in the same fractions of the old Holocene soils. Calculated to a soil depth of 60 cm the K release in kg/ha reaches from 25 000 (young soil form) to 17 000 (old soil form).  相似文献   

18.
This paper is based on the results of the study of soils and soil-forming rocks on five key sites in Iceland, including the coastal plain (the Hvammur key site), piedmont plain (the Hveragerði key site), the Holocene lava plateau (the Reykjanes key site), and the zone of modern hydrothermal activity in the north of the rift zone of Iceland (the Theistareykir and Námafjall key sites). The studied soils are subdivided by us into the groups of exothermic and endothermic soils. Exothermic soils are the soils that develop from the congealed volcanic deposits. These soils are specified by the homogeneous dark gray color and sandy texture. Their mineral components are weakly transformed. Exothermic soils developed under good drainage conditions have the low content of organic matter (about 1.5% Corg). The soil reaction is neutral within the entire profile. Under impeded drainage conditions, the organic carbon content in the exothermic soils reaches its maximum of about 7%, and the soil reaction varies from acid to neutral values. Endothermic soils are the soils that are subjected at present or were subjected in the past to the high-temperature hydrothermal metamorphism. They have mottled color patterns with sharp color contrast in the soil profile; their texture is loamy or clayey. These soils are rich in secondary minerals with a predominance of smectite; kaolinite, pyrite, anatase, gypsum, and other secondary minerals can also be found in them. The properties of endothermic soils are largely controlled by the provincial features of the hydrothermal activity, including the chemical composition of hydrothermal water, the soil temperature, the duration of hydrothermal activity, etc.  相似文献   

19.
The diversity of soils in the southwestern part of the Pacific coast of Russia (Primorie region) is discussed. Overall, 17 soil types belonging to 8 soil orders have been described in this region, and their morphology and properties have been studied. The diversity of plant communities, geomorphic conditions, and parent materials and relatively mild (as compared with other parts of the Far East region of Russia) specify the great variability of soil cover patterns. Low sea terraces are occupied by various peat, organo-accumulative, and gley soils; poorly drained medium-high terraces are the areas of various dark-humus and darkhumus gleyed soils. Typical and gleyic dark-humus podbels, dark-humus, and dark-humus gleyed soils formed on the high sea terraces. Residual elevations are occupied by brown forest (burozemic) soils, including typical burozems, dark-humus burozems, and gleyic dark-humus burozems and by dark-humus podbels. Various alluvial, gleyic gray-humus, and mucky gley soils are developed on riverine plains. On general, darkhumus soils with the high (>10%) humus content predominate; the area of dark-humus podbels us estimated at about 20%, and the area of dark-humus burozems is about 12%. All the soils in this region are specified by increased acidity values. The exchangeable sodium content is often high in the upper soil horizons with maximum values (0.71–1.19 cmol(c)/kg) in the peat gleyzems, peaty dark-humus soils, mucky-gley soils, and eutrophic peat soils of sea terraces. The grouping of the soils with respect to their physicochemical and agrochemical properties is suggested.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号