黏土矿物组成对天山北坡土壤变性特征的影响

【目的】调查天山北坡是否分布有变性特征的土壤,通过测定其黏土矿物组成,探讨新疆变性土壤发育的内在矿物学机制。【方法】使用传统野外调查方法,研究天山北坡11个土壤剖面,根据裂隙、滑擦面、楔状结构等诊断特性的发育状况划分其变性化程度。测定了研究剖面28个土壤发生层的线胀系数和黏土矿物中蒙皂石的含量,并探讨其相关性。【结果】研究的11个土壤剖面中有4个剖面可相对划分为强变性化的土壤,28个土层蒙皂石含量的平均值为38%。强变性化程度土壤中蒙皂石的含量显著高于弱变性化程度的土壤。蒙皂石含量与线胀系数之间存在极显著的幂函数关系。【结论】较低的蒙皂石含量是决定本研究调查的土壤变性化程度不高的内在原因。未来在新疆开展变性土调查时,需要重点考虑蒙皂石含量高的成土母质分布区。

浅谈温室土壤变性及其改良

随着经济的发展，我国花卉事业飞速发展。各地建起大型温室和塑料大棚，通过人为控制环境因子和采用先进的栽培技术，几乎在不受外界气候影响的条件下，一年四季培育各种花卉，满足人们对花卉的需要。但在温室栽培条件下，往往是新建的温室花卉生长良好，时间一久花卉的长...

考虑土壤时变性与频变性的接地体冲击特性研究

发生雷击故障时,接地体起到泄放故障电流的作用。由于雷电流幅值与瞬时频率均随注入时间快速变化,在雷电流作用下注流点附近土壤电气参数同时呈现时变性和频变性,忽略土壤的时变性和频变性会给接地体的冲击阻抗计算带来误差。针对土壤的频变性,通过希尔伯特黄变换对雷电流作时频域分解,用Viascro-Alipio土壤频变公式对土壤电阻率、介电常数等频变参数进行修正;针对土壤的时变性,将接地体分段,计算各段随时间变化的火花放电区域等效半径,建立了考虑土壤时变性和频变性的接地体暂态模型,并与文献真型试验结果对比验证其有效性。通过模型分析土壤频变性的影响,发现土壤电气参数的频变性会使接地体的冲击阻抗有所下降,在土壤电阻率高与冲击电流陡度大的情况下,其影响更加明显。

计及土壤频变性的接地装置频域性能分析

电力工业的发展和全球气候的复杂变化,导致故障或雷击时接地系统面临新的问题。准确计算接地装置的频域性能可为接地系统优化设计提供合理依据。采用基于电磁场理论的有限元方法,通过加入Visacro-Alipio土壤频变公式,建立了计及土壤频变性的接地装置频域性能分析模型。通过比较接地网的仿真计算结果与CDEGS软件计算结果,验证了本文算法的准确性。对水平和垂直接地极频域性能的分析结果表明高频下计及土壤参数频变性时接地参数计算结果明显降低,准确性更高。

土壤频变性对接地装置冲击系数的影响分析

冲击系数是反映输电线路杆塔接地装置冲击特性的重要参数,对其进行准确计算是防雷优化设计和提升输电线路耐雷性能的基础。在深入分析土壤介质微观极化过程的基础上,引入Visacro-Alipio土壤频变特性公式,建立了考虑土壤电参数频变性的接地装置冲击特性数值模型;利用所建模型仿真分析了考虑土壤频变性时土壤电阻率、冲击电流波形等因素对接地装置冲击系数的影响规律。仿真数据分析表明考虑土壤频变性时接地装置的冲击系数与不考虑土壤频变性时的冲击系数相比有一定减小,在高土壤电阻率及陡波前冲击电流作用下其减小程度更明显。

Effect of Combined Application of Manure and Chemical Fertilizer on the Dynamic Changes of Purple Soil Nutrient and Soil Enzyme Activities

[Objective] The aim was to study the effects of combined of manure and fertilizer on the content of nutrients in purplish soil as well as release dynamics of enzyme activities.[Method] The effects of manure and fertilizer application on the content of AOM,NH＋4-N and NO-3-N in soil as well as release dynamics of enzyme activities were studied by means of simulation culturing.[Result] In the treatments of combined application of simulation culture experiment,the content of active organic matters,NH＋4-N,NO-3-N and soil enzyme activities changed dynamically,which showed a shape of inverted ＂S＂ with two or more peaks.Compared with the treatment of fertilization,their peaks were relatively flat and occurred relatively late,while the treatment of fertilization had only one but the highest peak.The content of active organic matter came to top around 10 d in the order of cow5fertilizer5pig5fertilizer5cow manurepig manurefertilizer Ⅰfertilizer Ⅱ;the activity of urease came to top around 10 d in all treatments and in the order of pig manurecow5fertilizer5cow manurefertilizer Ⅰfertilizer Ⅱpig5fertilizer5.The activity of saccharase was in the order of pig5fertilizer5pig manurecow5fertilizer5cow manureCKfertilizer Ⅱfertilizer Ⅰ.[Conclusion] The study could provide the theoretical basis for reasonable application of manure and fertilizer.

Vertical Variation Characteristics of Basic Physical Properties in the Daxia Irrigated Area of Qinghai Province

Influenced by climate, biology and soil properties, vertical soil profile showed stratification character in terms of basic physical properties. The research conducted measurement and analysis on basic physical properties of typical field in the Daxia irrigation area in Qinghai Province. The results showed that soil bulk density changed from decreasing to increasing upon soil horizon; the soil horizons in 0-40 and 90-150 cm were high porosity zones, and the others were low porosi- ty area; the saturation moisture capacity, water retention of capillary porosity and field water retention all changed from decreasing to increasing upon soil horizon featured by arithmetic progression. In addition, the research area in Daxia irrigated area showed loose structure in soil horizon of 0-40 cm, compacted in 40-60 cm, and loose again in 60-200 cm vertically.

Spatial Variability of Nutrient Properties in Black Soil of Northeast China

A total of 1400 soil samples from the plow layer （0-20 cm） at an approximate interval of 5 km were collected in the autumn of 2002 over the entire black soil arable crops region to determine the spatial variability of seven variables, such as total organic matter content （OMC）, total N, total P, total K, alkali-dissolvable N （AN）, available P （AP） and available K （AK）, with classical statistics and geostatistical analysis across the entire black soil area in Northeast China. In nonsampled areas ordinary kriging was utilized for interpolation of estimated nutrient determinations. Classical statistics revealed highly significant （P ≤ 0.01） correlations with all seven of the soil properties, except for OMC with AP and total K with AK. In addition, using coefficients of variation, all soil properties, except for total K, were moderately variable. A geostatistical analysis indicated that structural factors, such as parent material, terrain, and water table, were the main causes of the spatial correlations. Strong spatial correlations were noted with OMC, total N, total P, AN, and AP, while they were moderate for total K and AK. The effective spatial autocorrelation of OMC, total N, total P, and AN ranged from 1 037 to 1353 km, whereas the ranges of total K, AP, and AK were only from 6 to 138 km. The fit of the experimental scmi-variograms to the theoretical models indicated that except for AN, kriging could successfully interpolate other six variables. Thns, the geostatistical method used on a large scale could accurately evaluate the spatial variability of most black soil nutrient properties in Northeast China.

Small-Scale Spatial Variability of Soil Nutrients and Vegetation Properties in Semi-Arid Northern China

A field experiment was conducted at Kezuohouqi County, Inner Mongolia Autonomous Region of China, which was located on the southeastern edge of the Horqin Sandy Land, to study the spatial variability of soil nutrients for a smallscale, nutrient-poor, sandy site in a semi-arid region of northern China; to investigate whether or not there were 'islands of fertility' at the experimental site; and to determine the key nutrient elements that sustained ecosystem stability. Results obtained from geostatistical analysis indicated that the spatial distribution pattern of soil total nitrogen (STN) was far different from those of soil organic matter (SOM), total phosphorus (STP), and total potassium (STK). Compared to SOM, STP, and STK, STN had a lower structural heterogeneity ratio and a longer range, while other elements were all similar. In addition, STN had an isotropic spatial structure, whereas the others had an anisotropic spatial structure. The spatial structure patterns of herbage species, cover,and height also differed, indicating that spatial variability was subjected to different ecological factors. Differences in the spatial variability patterns among soil nutrients and vegetation properties showed that soil nutrients for a small-scale were not the primary limiting factors that influenced herbage spatial distribution patterns. Incorporating spatial distribution patterns of tree species, namely, Pinus sylvestris var. mongolica Litv. and shrub Lespedeza bicolor Turcz. in a research plot and using fractal dimension,SOM, STP, and STK were shown to contribute to the 'islands of fertility' phenomenon, however STN was not, possibly meaning that nitrogen was a key limiting element. Therefore, during restoration of similar ecosystems more attention should be given to soil nitrogen.

Monitoring and Evaluation of Soil Changes Under Landuse of Different Patterns at a Small Regional Level in South China

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Neural Network Ensemble Residual Kriging Application for Spatial Variability of Soil Properties

High quality, agricultural nutrient distribution maps are necessary for precision management, but depend on initial soil sample analyses and interpolation techniques. To examine the methodologies for and explore the capability of interpolating soil properties based on neural network ensemble residual kriging, a silage field at Hayes, Northern Ireland, UK, was selected for this study with all samples being split into independent training and validation data sets. The training data set, comprised of five soil properties: soil pH, soil available P, soil available K, soil available Mg and soil available S,was modeled for spatial variability using 1) neural network ensemble residual kriging, 2) neural network ensemble and 3) kriging with their accuracies being estimated by means of the validation data sets. Ordinary kriging of the residuals provided accurate local estimates, while final estimates were produced as a sum of the artificial neural network (ANN)ensemble estimates and the ordinary kriging estimates of the residuals. Compared to kriging and neural network ensemble,the neural network ensemble residual kriging achieved better or similar accuracy for predicting and estimating contour maps. Thus, the results demonstrated that ANN ensemble residual kriging was an efficient alternative to the conventional geo-statistical models that were usually used for interpolation of a data set in the soil science area.

Measurement and analysis of soil nitrogen and organic matter content using near-infrared spectroscopy techniques

Near infrared reflectance （N1R） spectroscopy is as a rapid, convenient and simple nondestructive technique useful for quantifying several soil properties. This method was used to estimate nitrogen （N） and organic matter （OM） content in a soil of Zhejiang Province, Hangzhou County. A total of 125 soil samples were taken from the field. Ninety-five samples spectra were used during the calibration and cross validation stage. Thirty samples spectra were used to predict N and OM concentration. NIR spectra of these samples were correlated using partial least square regression. The regression coefficients between measured and predicted values of N and OM was 0.92 and 0.93, and SEP （standard error of prediction） were 3.28 and 0.06, respectively, which showed that NIR method had potential to accurately predict these constituents in this soil. The results showed that NIR spectroscopy could be a good tool for precision farming application.

Temporal Variability in Soil CO_2 Emission in an Orchard Forest Ecosystem

Temporal variability in soil CO2 emission from an orchard was measured using a dynamic open-chamber system for measuring soil CO2 effiux in Heshan Guangdong Province, in the lower subtropical area of China. Intensive measurements were conducted for a period of 12 months. Soil CO2 emissions were also modeled by multiple regression analysis from daily air temperature, dry-bulb saturated vapor pressure, relative humidity, atmospheric pressure, soil moisture, and soil temperature. Data was analyzed based on soil moisture levels and air temperature with annual data being grouped into either hot-humid season or relatively cool season based on the precipitation patterns. This was essential in order to acquire simplified exponential models for parameter estimation. Minimum and maximum daily mean soil CO2 effiux rates were observed in November and July, with respective rates of 1.98 ± 0.66 and 11.04 ± 0.96 μmol m^-2 s^-1 being recorded. Annual average soil CO2 emission （FCO2） was 5.92 μmol m^-2 s^-1. Including all the weather variables into the model helped to explain 73.9% of temporal variability in soil CO2 emission during the measurement period. Soil CO2 effiux increased with increasing soil temperature and soil moisture. Preliminary results showed that Q10, which is defined as the difference in respiration rates over a 10 ℃ interval, was partly explained by fine root biomass. Soil temperature and soil moisture were the dominant factors controlling soil CO2 effiux and were regarded as the driving variables for CO2 production in the soil. Including these two variables in regression models could provide a useful tool for predicting the variation of CO2 emission in the commercial forest Soils of South China .

Spatial Patterns of Soil Heavy Metals in Urban-Rural Transition Zone of Beijing

To identify the main sources responsible for soil heavy metal contamination, 70 topsoils were sampled from the Daxing County in the urban-rural transition zone of Beijing. The concentrations of heavy metals Cu, Zn, Pb, Cr, Cd, Ni, As, Se, Hg, and Co; the soil texture; and the organic matter content were determined for each soil sample. Descriptive statistics and geostatistics were used to analyze the data, and Kriging analysis was used to estimate the unobserved points and to map the spatial patterns of soil heavy metals. The results showed that the concentrations of all the soil heavy metals exceeded their background levels with the exception of As and Se. However, only the Cd concentration in some areas exceeded the critical value of the national soil quality standard. The semivariance analysis showed that the spatial correlation distances for soil Cu, Zn, Cr, Cd, As, Ni, and Co ranged from 4.0 to 7.0 km, but soil Se, Pb, and Hg had a larger correlation distance. Soil Co, Se, Cd, Cu and Zn showed a strong spatial correlation, whereas the other soil heavy metals showed medium spatial correlation. Soil heavy metal concentrations were related to soil texture, organic matter content, and the accumulation of heavy metals in the soils, which was because of air deposition and use of water from the Liangshui, Xinfeng, and Fenghe rivers that are contaminated by wastewater and sewage for the purpose of irrigation of fields. Hence, a comprehensive treatment plan for these rivers should be formulated.

Spatial Variability of Soil Properties at Capulin Volcano,New Mexico,USA:Implications for Sampling Strategy

Non-agricultural lands are surveyed sparsely in general.Meanwhile,soils in these areas usually exhibit strong spatial variability which requires more samples for producing acceptable estimates.Capulin Volcano National Monument,as a typical sparsely-surveyed area,was chosen to assess spatial variability of a variety of soil properties,and furthermore,to investigate its implications for sampling design.One hundred and forty one composited soil samples were collected across the Monument and the surrounding areas.Soil properties including pH,organic matter content,extractable elements such as calcium (Ca),magnesium (Mg),potassium (K),sodium (Na),phosphorus (P),sulfur (S),zinc (Zn),and copper (Cu),as well as sand,silt,and clay percentages were analyzed for each sample.Semivariograms of all properties were constructed,standardized,and compared to estimate the spatial variability of the soil properties in the area.Based on the similarity among standardized semivariograms,we found that the semivariograms could be generalized for physical and chemical properties,respectively.The generalized semivariogram for physical properties had a much greater sill value (2.635) and effective range (7 500 m) than that for chemical properties.Optimal sampling density (OSD),which is derived from the generalized semivariogram and defines the relationship between sampling density and expected error percentage,was proposed to represent,interpret,and compare soil spatial variability and to provide guidance for sample scheme design.OSDs showed that chemical properties exhibit a stronger local spatial variability than soil texture parameters,implying more samples or analysis are required to achieve a similar level of precision.

Formation and Evolution of Vertisols in Huaibei Plain

The objectives of the present paper are to restore soil-forming environment of the Vertisols,to reveal their regularities of formation and evolution and to found soil chronology.In regard to formation and evolution of the Vertisols in the Huaibei Plain,they have undergone 3 cycles of deposition-formation during different geologic time (Q3^3;Q4^2 and Q4^3).Therefore,they are considered as the soils developed on heterogeneous parent material.The Vertisols as a paleosol can be divided into relict Vertisols and buried Vertisols.The former is shajiang black soils called by local people,the latter is shajiang black soils underlying Warp soil or warp soil horizon.

Age and Some Genetic Characteristics of Vertisols in China

The ages of organic matter of some dark-colored horizons and calcareous concretions in some Vertisols from tropical, subtropical and warm-temperate zones of China were studied using radiocarb on dating method. The relationship between soil age and genesis of Vertisols was also expounded based on the study of their genetic charactens-tics and micromorphological features. The results show that although Vertisols have developed for a relatively long time, their weathering and soil forming process are weak and young with little horizonation. This is closely related to their special geochemical soil forming environment. Low-lying terrain, heavy texture, clay minerals dominated by montmorillonites and alternative drying- wetting climate give rise to the vertic features expressed in intense swelling-shrinking and cracking-closing in soils. As a result, the soil development and soil leaching process are resisted, and the climatic effect on the horizonation is impeded. Moreover, pedoturbation eliminates the horizonation in the upper part of soil profile, and postpones their evolution into zonal soils. So Vertisols show certain pedogenic inertia and stay at relatively young developmental stage. Therefore, Vertisols are intrazonal soils dominated by local soil forming factors such as the relief and parent materials.

Stable Carbon and Oxygen Isotopes of Pedogenic Carbonates in Ustic Vertisols: Implications for Paleoenvironmental Change

Pedogenic carbonates, found extensively in arid and semiarid regions, are important in revealing regional climatic and environmental changes as well as the carbon cycle. In addition, stable carbon and oxygen isotopic compositions of pedogenic carbonates have been used to rebuild paleoecology (biomass and vegetation) and to estimate paleotemperature and paleoprecipitation during past geological time. By utilizing the stable carbon and oxygen isotopic compositions (δ13C and (δ18O) of secondary nodules in Ustic Vertisols, this study looked into the climatic and environmental changes in the dry valleys of the Yuanmou Basin, Yunnan Province, in southwestern China. The results showed that during the early Holocene, a warm-humid or hot-humid climate existed in the Yuanmou Basin, but since then fluctuations in climate have occurred, with a dry climate prevailing. A highly significant correlation (r = 0.92, n = 9) between δ13C and δ18O values of carbonates illustrated that there had been a continual shifting between cold-humid and warm-dry climates in southwestern China including the Yuanmou Basin since the early Holocene.

Nonlinear analysis of consolidation with variable compressibility and permeability

Terzaghi gave a theory of soil consolidation based on the effective stress principle, which was derived on several ideal assumptions to get a simplified theory. To avoid the limitations involved in Terzaghi’s theory, many efforts are being made by scholars to solve the problems in practical engineering situations. This paper presents a generalized theory for one dimensional consolidation of saturated soft clay with variable compressibility and permeability. The semi-analytical solution presented here takes into account the well known empirical e-logk and e-logp′(σ′) relations under instantaneous loading. Study of the consolida- tion behaviors showed that the ratio of Cc and Ck (the slope of e-logp and e-logk respectively) govern the ratio of consolidation. A simulative laboratory investigation with GDS advanced consolidation system was made to analyze the clay consolidation process and compare the results with the semi-analytical solution.

Properties, Formation and Fertility of Vertisols in Fujian Province

The zonal soils in the south subtropical zone of Fujian are lateritic red soils. A type of dark clayeysoils, which was historically defined as lateritic red soils, derived from weathering products of the basalts wasindicated by the investigation results to be markedly different from lateritic red soils and could be classifiedas Typical Hapluderts. They are distributed as complex zones with the lateritic red soils. The vertisolsin this region were considered as a type of lithogenic soils and the vertic chararteristics delay and inhibitthe soils from allitic processes and then formed an independent soil type. The vertisols have higher fertilityand better agricultural production characters than the lateritic red soils. The different ways in utilizing andmanaging these soils arcording to their properties and fertility are also suggested.