Soils and the soil cover as witnesses and indicators of global climate change

Soils and the soil cover are witnesses to global changes on the planet; moreover, they play an active role in these changes. Investigations into the role of soils in global processes come to forefront of modern soil science; it is necessary to find appropriate criteria and indicators making it possible to diagnose global environmental changes and to assess their contribution to soil formation.     

Theoretical basis and practical significance of investigations into soil cover patterns

Principles and methods of studying the soil cover pattern for the inventory, assessment, and rational use of the natural resource potential are outlined. It is suggested that the soil cover patterns should be studied for typified natural systems (territorial units). The latter are different from one another in the composition and pattern of the soil combinations. The typology and hierarchical grouping of soil combinations are developed, and their nomenclature is suggested. The methodology for assessing the soil cover heterogeneity on the basis of a monofactor scale of the degree of the soil contrasts and a modified evaluation of the soil cover compartmentalization with the application of an automated cartographic analysis is described. This procedure has made it possible to gain an integral holistic perception of the geosystems in Belarus. The application of a corresponding database developed in the ArcInfo format for creating maps with information on the morphometric, geomorphic, hypsometric, lithological, and other characteristics of geosystems is illustrated. Special surveys of the soil cover patterns in Belarus were performed on an area of 10000000 ha. Their results are taken into account upon planning the rational nature management.     

Tillage and cover effects on soil microbial properties and fluometuron degradation

This research concerns the influence of no tillage (NT) or conventional tillage (CT) and a ryegrass (Lolium multiforum Lam.) cover crop in a cotton (Gossypium hirsutum L.) production system on soil and ryegrass microbial counts, enzyme activities, and fluometuron degradation. Fluorescein diacetate hydrolysis, aryl acylamidase, and colony-forming units (CFUs) of total bacteria and fungi, gram-negative bacteria, and fluorescent pseudomonads were determined in soil and ryegrass samples used in the degradation study. Fluometuron (14C-labelled herbicide) degradation was evaluated in the laboratory using soil and ryegrass. The CT and NT plots with a ryegrass cover crop maintained greater microbial populations in the upper 2 cm compared to their respective no-cover soils, and CT soils with ryegrass maintained greater bacterial and fungal CFUs in the 2–10 cm depth compared to the other soils The highest enzymatic activity was found in the 0–2 cm depth of soils with ryegrass compared to their respective soils without ryegrass. Ryegrass residues under NT maintained several hundred-fold greater CFUs than the respective underlying surface soils. Fluometuron degradation in soil and ryegrass residues proceeded through sequential demethylation and incorporation of residues into nonextractable components. The most rapid degradation was observed in surface (0 to 2 cm) soil from CT and NT–ryegrass plots. However, degradation occurred more rapidly in CT compared to NT soils in the 2 to 10 cm depth. Ryegrass cover crop systems, under NT or incorporated under CT, stimulated microbiological soil properties and promoted herbicide degradation in surface soils.     

土壤-植物系统中氟的迁移转化规律及研究展望

氟不仅以气体的形态存在于大气中,而且还以水溶性化合物形态存在于土壤和地下水。氟污染的地区,作物因土壤中氟过量而出现生长异常,人和动物通过饮水和食物摄取过多的氟而使健康受到严重威胁。本文从氟在土壤中的地球化学特征、作物对氟的吸收富集、氟污染对人体和动物健康的危害等几个方面的国内外研究进展出发,就氟对土壤的生态环境效应进行综述,同时对今后的相关研究进行了展望。     

土壤质量评价指标及其时空变异

综述了土壤质量的概念及其研究进展,并探讨了土壤质量指标的选择原则,得出不同土壤的评价应以土壤的功能为基础并采用不同的标准。在以往研究中,人们一直强调以土壤物理、化学特性作为土壤质量指标。目前,国内外关于土壤生物学指标的研究日益增多,一些参数作为生物指标已表现出很大的潜力并成为系统稳定性的早期预警和敏感指标。之后阐述了国内外土壤质量指标空间变异的研究现状,探讨了该领域研究中存在的问题,展望了国内外土壤空间变异的研究前景。     

Dynamics of landuse/cover changes and degradation of Nairobi City,Kenya

Landuse/cover in Nairobi City is changing rapidly because of the increased interactions of human activities with the environment as population increases. We used multi‐temporal Landsat images (1976, 1988 and 2000) together with physical and socio‐economic data in a post‐classification analysis with GIS to map landuse/cover distribution and to analyse factors influencing the landuse/cover changes for Nairobi City. An unsupervised classification approach, which uses a minimum spectral distance to assign pixels to clusters, was used with the overall accuracy ranging from 87 per cent to 90 per cent. Landuse/cover statistics revealed that substantial landuse/cover changes have taken place and that the built‐up areas have expanded by about 47 km² over the study period (1976–2000). Forests have decreased substantially while agricultural lands have been on the increase. Rapid economic developments together with the increasing population were noted to be the major factors influencing rapid landuse/cover changes. Urban expansion has replaced agricultural farmlands and other natural vegetation, thereby affecting habitat quality and leading to serious environmental degradation. The random, unplanned growths of environmentally degraded squatter settlements were noted to be emerging in the rural fringes. Successful planning of Nairobi's development will require reliable information about landuse/cover changes and factors influencing such changes. Copyright © 2006 John Wiley & Sons, Ltd.     

Development of the visual loop-mediated isothermal amplification assays for seven genetically modified maize events and their application in practical samples analysis

As more and more genetically modified (GM) crops are approved for commercialization and planting, the development of quick and on-spot methods for GM crops and their derivates is required. Herein, we established the polymerase chain reaction and agarose gel electrophoresis-free system for the identification of seven GM maize events (DAS-59122-7, T25, BT176, TC1507, MON810, BT11, and MON863) employing a loop-mediated isothermal amplification (LAMP) technique. The LAMP assay was performed using a set of four specific primers at 60-65 °C in less than 40 min, and the results were observed by direct visual observation. In these developed assays, the specificity targeted at each GM maize event based on the event-specific sequence was well confirmed, and the limits of detection were as low as four copies of maize haploid genomic DNA with an exception of 40 copies for MON810 assay. Furthermore, these developed assays were successfully used to test six practical samples with different GM maize events and contents (ranged from 0.0 to 2.0%). All of the results indicated that the established event-specific visual LAMP assays are more convenient, rapid, and low-cost for GM maize routine analysis.     

Methane dynamics of landfill cover soils and aspects of their classification

The methane dynamics of soils covering a landfill in Oldenburg, Lower Saxony, was investigated in 1996. The methane concentration was often < 20 nmol (dry g)^?1 within the cover layer and up to 9950 nmol (dry g)^?1 within the refuse body. The methane production rates correlated positively with the methane concentrations and were mostly < 10 nmol (dry g)^?1 d^?1 within the cover layer and up to 1090 nmol (dry g)^_1 d^_1 within the refuse body. The methane oxidation rates varied between 38.0–2310 nmol (dry g)^?1 d^?1. The methane emission rates showed values of up to 574 mol m^?2 h^?1, but in two cases no emission of methane was found. The data indicate that the methano-genesis of the deep refuse layers did not substantially affect the methane behaviour of the upper soil sections. It is likely that the emission of methane from landfills can be reduced by thick well aerated cover layers. The term “Reduktosol” for landfill soils is critically discussed.     

Changes in the geometric structure of pores and aggregates as indicators of the structural degradation of cultivated soils

As shown by the example of loamy soils of the European territory of Russia, the geometric parameters of soil structure, along with the agrophysical soil parameters, should be taken into account for the comprehensive assessment of the physical degradation of cultivated soils. Different variants of the geometric transformation of soil structure in the plow horizons are analyzed. The shape and orientation of soil pores in thin sections prepared from undisturbed oriented soil samples are considered to be the main diagnostic indices. A computer-aided analysis of soil pores in thin sections made it possible to distinguish and characterize different levels of the geometric transformation of soil structure upon soil compaction: (a) without the disturbance of the shape and orientation of the aggregates, (b) with the transformation of soil aggregates from the crumb (granular) to the angular blocky shape, (c) with the development of a platy structure characterized by the predominantly horizontal orientation of the pores and aggregates, and (d) the complete disappearance of separate aggregates with the formation of a massive soil structure. The validity of the assessments of the geometric transformation of the soil pore space against the background of a considerable spatial variability in the geometric properties of soil structure in the plow horizon is discussed. The structural-functional specificity of the distinguished levels of the geometric transformation of soil structure is outlined.     

Spatial patterns of soil crusting and their relationship to crop cover

The interactions between the spatial pattern of soil crust development and crop cover conditions are investigated through controlled laboratory experiments using rainfall simulation. The experimental responses are monitored by using terrestrial photogrammetry and results quantified and analysed in a geographical information system. The generated categorical data is used within a stepwise logistic modelling framework. Results obtained show for the experimental conditions that the expected results of a decrease in areal crust development with increase in crop cover do not hold true. These results are being explained in terms of differences in crop morphology of the two crops used: sweet corn and cabbages, and the specific properties of the soil used in the experiments.     

Soil degradation processes and their control in Hungary

Soil degradation is usually a complex process in which several features of soil deterioration can be recognized. Soil degradation may lead to the loss of land or soil; limitations to normal soil functions; decrease of soil fertility and ‘productive capacity’. The main soil degradation process are: (1) soil erosion by water and wind; (2) Development of extreme soil reaction (acidification; salinization/alkalization); (3) physical degradation (structural destruction; compaction; extreme moisture regime); (4) biological degradation; (5) unfavourable changes in the nutrient regime; (6) decrease of buffering capacity (leading to pollution, toxicity). Soil degradation is not an unavoidable consequence of intensive agriculture and social development. Most of the processes and their unfavourable consequences can be controlled, prevented, eliminated, or at least moderated. A rational strategy of efficient soil degradation control should be based on a system involving the following (consecutive) steps: (a) registration of facts and consequences; (b) analysis of reasons, processes, influencing factors and their mechanisms; (c) determination of the theoretical, real, rational and economic possibilities for control; (d) prediction of the potential impacts of these control alternatives; (e) elaboration and extension of technologies for the optimum alternatives. The present status of soil degradation processes in Hungary is briefly summarized in this paper and the possibilities for control are reviewed, with special regard to soil erosion, salinization/alkalization, acidification and physical degradation (compaction, structure destruction). Based on detailed and comprehensive information on soils (thematic maps of various scales; computerized geographical soil information system) the potential future development of various soil degradation processes is forecast and technologies are elaborated and recommended for use in Hungarian agriculture to prevent soil degradation.     

水稻秸秆降解复合菌系的筛选构建及其田间应用效果

[目的]筛选并构建适宜原位还田水稻秸秆快速腐解的高效多功能复合菌系,以提高秸秆原位还田的腐解速率.[方法]秸秆原位腐解菌株从水稻田带有腐烂秸秆的表层土壤中筛选分离,分别采用DNS法、摇瓶培养观察法和失重法测定了腐解菌株的羧甲基纤维素酶活性、滤纸崩解能力及水稻秸秆降解能力,对降解效果较好的菌株进行了16S rRNA或18...     

土壤质量诊断与评价理化指征及其应用

介绍了澳大利亚科工组织建立的流域健康诊断指征体系的指征选择原则、13项诊断指征、指征评 价方法与评价过程。并以此方法筛选和评价出太行山前平原农田土壤质量诊断的理化指征,提出了以经验性指征、形态学与物理学指征和化学指征综合评价该区土壤质量的指征体系。     

Changes in maturity indicators during the degradation of organic wastes subjected to simple composting procedures

Selected maturity indicators were monitored over a period of 335 days during the degradation of organic wastes subjected to four simple composting procedures, which varied in raw material (garden refuse with and without market refuse) and turning frequency (0×, 6×). All procedures produced mature composts. The inclusion of market refuse and frequent turning generally increased the cation exchange capacity of compost on an ash-free basis. Until day 118 of the composting process, compost samples which contained market refuse in their raw material mixture had the lowest redox potentials after anaerobic incubation. Cress grown on these composts also produced the lowest fresh mass. At a later stage of the composting process, the same composts displayed increased cellulolytic activity. Frequent turning of the compost heaps resulted in greater fluorescein diacetate hydrolysis, a greater occurrence of low-molecular-weight humic compounds and, occasionally, an inhibition of cellulolytic activity. The arginine ammonification assay gave information on the N-status of the composts, rather than on the compost maturity, and suggested that all the composts could be safely applied to soil with no risk of microbial immobilisation of soil N.     

土壤芽孢杆菌及其资源的持续利用

本文简介了芽孢杆菌属的主要特征及其分类系统的发展历程 ;分析了土壤中芽孢杆菌资源的研究和利用现状并论述了芽孢杆菌属细菌在农业、科研、工业、医药等领域的研究、应用近况     

Influence of soil properties on the aggregation of some Mediterranean soils and the use of aggregate size and stability as land degradation indicators

Soil aggregation in relation to other soil properties was studied along a climatological transect in the Southeast of Spain. Three sites were selected along this transect ranging from semiarid to subhumid climatological conditions. The aggregate size distribution, the macro and microaggregate stability of the superficial soil horizon and their relations with other soil properties were analysed. Large aggregates (>10, 10–5, 5–2 mm) were present in highest proportions in the most arid of the studied areas. These large aggregates were associated with high values of water-stable microaggregates; however, they did not improve soil structure and are related to high bulk densities and low water retention. Aggregates 1–0.105 mm were positively correlated to medium, fine, very fine sand and silt fractions and to organic matter. Aggregates <0.105 mm were positively correlated to organic matter and clay content. Small aggregate sizes (1–0.105 and <0.105 mm) had a positive influence on soil water retention and they seem a good indicator of soil degradation.Water stability of microaggregates showed a positive correlation with clay content while the stability of the macroaggregates depended on the organic matter content when the organic matter content was greater than 5 or 6%. Below that threshold the carbonate content was strongly correlated with aggregate stability. A general conceptual scheme of associations between aggregate size distribution, water-stable microaggregation and textural characteristics for the area was developed.The land use history affecting soil overlaps the pattern of climatological situations and has to be taken into account. Aggregate size distribution and stability can be used as indicator of soil degradation, but not as a unique parameter.     

臭氧降解花生中黄曲霉毒素的设备及应用

为了高效降解花生中黄曲霉毒素,研制了一套臭氧降解黄曲霉毒素的设备。以人为污染的花生为试验材料,利用此设备研究了臭氧处理时间及其相对湿度对花生脱毒效果的影响。研究结果表明:臭氧能有效降解花生中的黄曲霉毒素,且臭氧处理时间和相对湿度显著影响其降解效果(P<0.05)。在臭氧浓度89mg/L、流速1L/min、搅拌速度70r/min条件下,黄曲霉毒素的较佳降解工艺为:臭氧相对湿度50%,处理时间30min。在此条件下,花生中黄曲霉毒素B1、B2、G1和G2的含量分别从87.53、21.99、9.71和4.38μg/kg降低到15.23、8.31、2.81和2.11μg/kg,降解率分别为82.6%、62.2%、71.1%和51.8%。研究结果可为花生贮藏和加工企业降低花生中的黄曲霉毒素、确保花生食用安全性提供技术参考。     

Determination of glucosinolates using their alkaline degradation and reaction with ferricyanide.

Glucosinolates, a group of naturally occurring thioglucosides, are significant factors impairing the nutritional quality of rapeseed and postextraction rapeseed meal, restricting its use as high-quality protein animal feed. Currently, the European Community standards and Canola definition are being brought in line recommending cultivation and marketing of rapeseed with a glucosinolate content below 18 micromol of total glucosinolates per gram of seeds. Furthermore, some glucosinolates are of increasing interest in Brassica vegetables due to their proven cancer-preventing activities. A novel approach to the analysis of total glucosinolates is reported in this paper based on their alkaline degradation and subsequent reaction of released 1-thioglucose with ferricyanide. The reaction was followed spectrophotometrically using sinigrin and glucotropeaolin as model glucosinolates. The applicability of the method was demonstrated using rapeseed extracts after reducing the interfering effect of phenolics by their adsorption onto polyvinylpolypyrrolidone. Good agreement with official ISO methods was shown.     

Soil cover patterns in the Dzhida Depression and their representation on the soil map of 1: 500000 scale

A map of the soil cover patterns in the Dzhida Depression (Baikal region) has been compiled on a scale of 1: 500 000. The grouping of the soil cover patterns into larger categories makes it possible to retain the information contained on large-scale soil maps upon their generalization to the small-scale soil map. The latter displays the regularities of soil distribution at the levels of soil types and subtypes. The areas of the major soil groups have been calculated. It is shown that podburs predominate in the northern taiga ecosystems (72%), whereas acid soddy taiga soils (71%) and podburs (22%) predominate in the middle taiga zone. Minor areas in these zones are occupied by podzolic soils (9%) and permafrost-affected taiga gley soils (14%).