Evaluation of Spatial Variability of Soil Properties in a Long-Term Experimental Tobacco Station in Southwest China

Analysis of the spatial variability of soil properties is important to arrange the experimental treatments in the experimental station. This paper aims to study the spatial structure of soil variables and their distribution in the Pengshui tobacco experiment station in Chongqing, China. Soil samples were taken from 289 soil points on 20 m grid in March 2012. Twenty-two soil chemical and physical properties were analyzed by classical statistical and geo-statistical methods. Soil pH, cation exchange capacity （CEC）, total phosphorus （TP）, available phosphorus （AP）, zinc （Zn）, magnesium （Mg） and sulphur （S） have the strong spatial dependence, with nugget/sill ratios of less than 25%. The others have the moderate dependence with nugget/sill ratios of 26.17% to 71.04%. Ranges of the spatial correlation varied from 51.30 m for chlorine （C1） to 594.90 m for TP. The clearly patchy maps of the nutrients showed the spatial distributions of the soil variables, which can be used for better management of experimental treatments, achieving reliable exoerimental results in the tobacco exnerimental station.Highlight： Scientific experimentation assumes the existence of random variability for soil attributes. This research was to evaluate the spatial variability of soil chemical and physical attributes and to interpolate the spatial distribution of soil properties in the tobacco experimental station in Chongqing. The result of this work can be used for the agricultural management of tobacco cultivation.

Spatial variability and pattern analysis of soil properties in Dehui city, Jilin province

Based on regionalized variable theory, semivariograms of geo-statistics wereused to research the spatial variation of soil properties quantitatively. The results showed thatthe semivariogram of soil organic matter is best described by spherical model, the best model forsemivariograms of soil total N and available K is exponential models and that of available P belongsto linear with sill model. Those soil properties have different spatial correlations respectively,the lag of organic matter is the highest and that of available P is the lowest, the spatialcorrelation of N and available K belongs to moderate degree. Spatial heterogeneities are differenttoo, the degree of organic matter and total N are higher, the degree of available K is in the nextplace and that of available P is the lowest. Influenced by the shape, topography and soil of thestudy area, all isotropies of available P are obvious in all directions while anisotropies of othersare manifested. According to the analytical results, supported by GIS, Kriging and IDW methods areapplied to describe and analyze the spatial distribution of soil properties. The results indicatethat soil organic matter, total N and available K are distributed regularly from northeast tosouthwest, while available P is distributed randomly.

Effect of Water Salinity on the Spatial Variability of Soil and Plant Parameters

Spatial pattern and interdependence of different soil and plant parameters were examined in green bean field experiment carried out at the Mediterranean Agronomic Institute of Bari （MAIB）, Italy. The study aimed to identify the spatial distribution of soil and plant parameters and their relationship at transects scale. The experiment consisted of three transects of 30 m length and 4.2 m width, irrigated with three different salinity levels （1 dSm＂1, 3 dSm1, 6 dSml）. Soil measurements （electrical conductivity and soil water content） were monitored along each transect in 24 sites, using TDR probe installed vertically at soil surface. Water storage was measured by using Diviner sensor for calculating directly the evapotranspiration fluxes along the whole soil profile under the different salinity levels imposed during the experiment. In the same 24 sites, crop monitoring involved measurements of Leaf Area Index （LAI）, Osmotic Potential （OP）, Root length Density （RID） and Evapotranspiration fluxes （ET）. Soil and plant properties were analyzed using both classical and geostatistical methods which included descriptive statistics, semivariograms and cross-semivariograms. Results indicated that moderate to large spatial variability existed across the field for soil and plant parameters, especially under the 6 dSm1 salinity treatment. A relatively satisfactory fit of the experimental cross-semivariogram was obtained for the 6 dS1, thus indicating similar spatial structures of the pairs of compared variables. By contrast, the experimental cross-semivariograms observed under the 3 dS~ treatment indicated no significant correlation structure between the compared variables. Overall, the results observed in the 3 dSm-1 were not significantly different from those obtained in the 1 dSm-1 transect and suggested a general insensitivity of the crop response to those levels of salinity.

Uncertainties of thermal boundaries and soil properties on permafrost table of frozen ground in Qinghai-Tibet Plateau

In the permafrost regions of the Qinghai-Tibet Plateau(QTP),the permafrost table has a significant effect on the stability of geotechnical engineering.The thermal boundaries and soil properties are the key factors affecting the permafrost table.Complex geological environments and human activities can lead to the uncertainties of thermal boundaries and soil properties.In this paper,an array of field experiments and Monte Carlo(MC)simulations of thermal boundaries and soil properties are carried out.The coefficient of variation(COV),scale of fluctuation(SOF),and autocorrelation distance(ACD)of uncertainties of thermal boundaries and soil properties are investigated.A stochastic analysis method of the probabilistic permafrost table is then proposed,and the statistical properties of permafrost table on the QTP are computed by self-compiled program.The proposed stochastic analysis method is verified with the calculated and measured temperature observations.According to the relationship between ACD and SOF for the five theoretical autocorrelation functions(ACFs),the effects of ACF,COV,and ACD of soil properties and the COV of thermal boundaries on the permafrost tables are analyzed.The results show that the effects of different ACFs of soil properties on the standard deviation(SD)of permafrost table depth are not obvious.The SD of permafrost table depth increases with time,and the larger the COVs of thermal boundaries and soil properties,the deeper the SD of permafrost table;the longer the ACD of soil properties,the shallower the SD of permafrost table.This study can provide a reference for the stability analysis of geotechnical engineering on the QTP considering the uncertainties of thermal boundaries and soil properties.

Spatial Variability of Soil Chemical Properties in the Reclaiming Marine Foreland to Yellow Sea of China

Precise information about the spatial variability of soil properties is essential in developing site-specific soil management, such as variable rate application of fertilizers. In this study the sampling grid of 100 m × 100 m was established to collect 1 703 soil samples at the depth of 0-20 cm, and examine spatial patterns including 13 soil chemical properties （pH, OM, NH4^＋, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn） in a 1 760 ha rice field in Haifeng farm, China, from 6th to 22nd of April, 2006, before fertilizer application and planting. Soil analysis was performed by ASI （Agro Services International） and data were analyzed both statistically and geostatistically. Results showed that the contents of soil OM, NH4^＋, and Zn in Haifeng farm were very low for rice production and those of others were enough to meet the need for rice cultivation. The spatial distribution model and spatial dependence level for 13 soil chemical properties varied in the field. Soil Mg and B showed strong spatial variability on both descriptive statistics and geostatistics, and other properties showed moderate spatial variability. The maximum ranges for K, Ca, Mg, S, Cu and Mn were all - 3 990.6 m and the minimum ranges for soil pH, OM, NH4^＋, P, Fe, and Zn ranged from 516.7 to 1 166.2 m. Clear patchy distribution of N, P, K, Mg, S, B, Mn, and Zn were found from their spatial distribution maps. This proved that sampling strategy for estimating variability should be adapted to the different soil chemical properties and field management. Therefore, the spatial variability of soil chemical properties with strong spatial dependence could be readily managed and a site-specific fertilization scheme for precision farming could be easily developed.

The effect of environmental factors on spatial variability in land use change in the high-sediment region of China＇s Loess Plateau

In areas with topographic heterogeneity, land use change is spatially variable and influenced by climate, soil properties, and topography. To better understand this variability in the high-sediment region of the Loess Plateau in which soil loss is most severe and sediment diameter is larger than in other regions of the plateau, this study builds some indicators to identify the characteristics of land use change and then analyze the spatial variability as it is affected by climate, soil property, and topography. We build two indicators, a land use change intensity index and a vegetation change index, to characterize the intensity of land use change, and the degree of vegetation restoration, respectively. Based on a subsection mean method, the two indicators are then used to assess the spatial variability of land use change affected by climatic, edaphic, and topographic elements. The results indicate that： 1） Land use changed significantly in the period 1998-2010. The total area experiencing land use change was 42,302 km2, accounting for 22.57%of the study area. High-coverage grassland, other woodland, and forest increased significantly, while low-coverage grassland and farmland decreased in 2010 compared with 1998.2） Land use change occurred primarily west of the Yellow River, between 35 and 38 degrees north latitude. The four transformation types, including （a） low-coverage grassland to medium-coverage grassland, （b） medium-coverage grassland to high-coverage grassland, （c） farmland to other woodland, and （d） farmland to medium-coverage grassland, were the primary types of land use change, together constituting 60% of the area experiencing land use change. 3） The spatial variability of land use change was significantly affected by properties of dryness/wetness, soil conditions and slope gradient. In general, land use changed dramatically in semi-arid regions, remained relatively stable in arid regions, changed significantly in clay-rich soil, remained relatively stable in clay-poor soil, changed dramatically in steeper slopes, and remained relatively stable in tablelands and low-lying regions. The increase in vegetation coincided with increasing changes in land use for each physical element. These findings allow for an evaluation of the effect of the Grain to Green Program, and are applicable to the design of soil and water conservation projects on the Loess Plateau of China.

吉兰泰盐湖盆地土壤颗粒分形特征与空间变异分析

[目的]阐明盐湖盆地流域土壤颗粒分形特征和空间变异特征,揭示区域土壤环境演变和影响因子的响应规律,为旱区盐湖流域沙害治理提供数据和理论支持。[方法]以吉兰泰盐湖盆地流域为研究区,布设50个土壤采样点,采集表层、50 cm、100 cm土层150个土壤样本,基于土壤粒径分布和土壤基本理化指标pH值、总溶解性固体TDS、总氮TN、含水率θ的测试数据,采用多因素相关分析的方法,分析了土壤分形维数与各粒级含量和土壤基本理化因子的相关性;应用地统计学方法对土壤剖面分形维数空间变异特征及分布规律开展了研究。[结果]研究区0—100 cm土壤质地以砂土、壤砂土为主,不同土层深度土壤质地类型基本一致,土壤颗粒分形维数D值为1.672~2.785。土壤分形维数与黏粒和粉粒呈极显著正相关,与粗砂、中砂、细砂呈显著负相关,0.1 mm粒径是D值随土壤粒径变化的分界值。D值与含水率、总氮在3土层均呈现显著正相关,而与pH值和TDS相关性不显著。土壤分形维数具有强烈的空间自相关性,各层土壤D值均呈现出由南向北逐渐增大的条块状镶嵌分布特征,流域北部的巴音乌拉山和乌兰布和沙漠地区是D值的高值区,西南部边缘的图格力高勒沟台地和东南部边缘的贺兰山地区是全流域D值的最低区域,土壤表层在吉兰泰盐湖附近有带状分布的高值区。[结论]受气候和人类活动的影响,吉兰泰盐湖盆地土壤质地发生变化,表层土壤颗粒风蚀严重,较深层土壤具有粗粒化现象,未来应加强土壤侵蚀和退化状况观测研究。

盐渍化农田土壤斥水性与理化性质的空间变异性

摘要通过对新疆玛纳斯县盐渍化土壤三个不同尺度（间距分别为50m、5m及0．5m）的284个样点取样分析测定，采用经典统计学、空间自相关、地统计学和分形理论对土壤斥水性与理化性质进行空间格局分析。结果表明：1）土壤斥水性和pH符合正态分布，其余土壤属性符合对数正态分布。三尺度下土壤各属性绝大多数表现为中等变异水平。2）三尺度下土壤各属性的Moran’s I系数变化具有相似性，在-0．8～0．6范围内波动。3）三尺度下土壤各属性的半方差函数理论模型大多数能用球状模型来拟合。4）在一定范围内，土壤各属性具有一定的分形特征，分形维数变化幅度为1．75～1．96。分析表明不同尺度下土壤斥水性与理化性质具有一定的差异。

土壤水盐空间变异尺度效应的研究

水文学和土壤学中的尺度问题是目前水土科学研究的前沿课题之一。该文利用空间信息科学——地质统计学、根据设计的各种田间网格,在一维和二维(平面)空间中初步研究了黄河河套平原长胜试验区中小尺度的土壤水分和盐分随采样尺度所表现出的空间变异(结构性)的某些规律,表明采样尺度的划分和选取与水分和盐分的空间变异性大小有密切关系,尺度效应的研究对于指导农业技术研究中野外采样系统设计、节省外业调查的工作量及科学地进行内业计算、评估和揭示农业工程中具有地学特征的区域性自然规律有重要作用。

吉林省德惠市土壤特性空间变异特征与格局

基于区变量理论,通过地统计学的半变异函数定量研究吉林省中部德惠市土壤有机质、全氮、速效钾和速效磷的空间异质性特征。表明土壤有机质的理论模型属于球状模型、全氮和速效钾的理论模型为指数模型、速效磷则属于有基台值的线状模型。空间结构上,有机质具有很强的空间相关性,全氮和速效钾的空间相关性属于中等程度,而速效磷则具有弱相关性。四种土壤养分的空间自相关范围具有明显的差异,有机质和全氮的有效变程最大,速效钾次之,速效磷的有效变程最小。受研究区形状、地形及土壤母质区域性差异的影响,速效磷各向同性显著,其他养分各向带状性比较明显。根据空间分异的分析结果,在GIS支持下,采用Kriging和IDW两种插值方法,分析研究区土壤养分的空间格局,表明土壤有机质、全氮、速效钾均自东北向西南有规律地分布;速效磷分布的随机性较强,较前三者结构性特征不明显。

农田养分空间变异研究——以江西省泰和县苏溪镇为例

以江西省泰和县苏溪镇苏溪村120hm2为研究区域,运用地统计学和GIS手段,对丘陵红壤地区农田土壤中的速效磷(P)、钾(K)、铜(Cu)、铁(Fe)、锰(Mn)、锌(Zn)、速效硼(B)和硫(S)、铵态氮(N)、速效钙(Ca)、镁(Mg)进行了变异系数分析、半方差分析、分数维分析并以K为例,利用插值模型做出了较合理的土壤养分空间分布图。

崇明县土壤主要理化指标的空间分布与变异特征

于上海市崇明县(崇明岛、长兴岛、横沙岛3岛)采集0～20cm表层土壤样品128个,采用经典统计学和地统计学相结合的方法,分析土壤有机质、全氮、有效磷、有效钾含量和土壤电导率、容重、pH值等数据,研究土壤特性的空间分布规律。结果表明:崇明3岛有效磷和电导率的分布具有强变异性,pH值的变异强度最弱,其他土壤特性均具有中等变异强度。土壤容重和pH值具有很强的空间相关性,而土壤有机质、全氮、有效磷和有效钾的空间相关性最弱,其分布受随机因素影响较大。Kriging空间插值分析表明,受农事活动和城镇效应的影响,崇明岛土壤有机质和全氮含量高值区主要集中于人为活动比较密集的地区,土壤容重和pH值分布趋势基本一致,呈现由东西两端向岛中央递减的趋势。崇明岛土壤有机质、全氮、有效磷和有效钾含量两两间呈显著相关关系(α=0.01)。

基于GPS和GIS的田间土壤特性空间变异性的研究

以一块面积约为 13 .3 hm2 的冬小麦田为研究区 ,利用 GPS接收机定位 ,按 5 0 m× 5 0 m设置网格 ,共取 63个采样点 ,测定土壤表层 (2 0 cm)内的土壤有机质、全氮、碱解氮、速效磷、速效钾、容重、田间土壤含水率和电导率 ,研究麦田土壤特性的空间变异规律。采用传统统计学和地统计学相结合的方法对所取的数据进行了分析 ,利用 Arcview3 .2软件的空间分析功能 ,绘制了表达这些土壤特性随机性和结构性的半方差图和空间分布图。研究结果表明 :所有土壤特性均服从正态分布 ;土壤容重具有弱变异强度 ,其它土壤特性具有中等变异强度 ;土壤有机质、全氮、碱解氮、速效钾和电导率具有很强的相关性 ,土壤容重、速效磷和含水率具有中等强度的空间相关性 ,土壤特性的相关距变化范围为 2 46.8～ 42 6.8m。该成果可为农田的定位施肥、灌溉以及其它的农田精细管理提供依据。

多嵌套空间尺度农田土壤重金属空间变异研究

运用地统计学技术对棕壤土典型地块进行了重金属多尺度嵌套空间变异和结构来源分析。选取5种反映土壤污染水平的典型重金属元素铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)、铬(Cr)以及类重金属元素砷(As)进行采样检测。利用克里格法插值拟合,选择最优拟合模型,确定了合理采样间距。结合半方差和分维数分析,研究确定了合理采样尺度。采取主成分分析和半方差分析相结合的方法,确定土壤重金属来源,指导农业管理措施。研究表明,农田土壤重金属主要由成土母质、降水灌溉和农药施肥构成。中等尺度符合半方差模型拟合,变程的范围从319 m到752 m不等。其中球面模型更适合土壤重金属空间分布拟合描述。

杭州市城乡结合带蔬菜地土壤铅铜含量的时空变异研究

土壤重金属时空变异研究在土壤可持续利用和生态环境保护过程中具有重要的意义。通过2001年和2005年两个时期在杭州市东郊传统蔬菜基地取样分析,用空间自相关全局Moran’s I系数、地统计学以及分形维数三种空间分析方法研究了土壤重金属Pb和Cu的时空变异特征。两个时期的Pb和Cu平均含量分别由38.73、31.20 mg kg-1增加至46.14、36.56 mg kg-1,并经检验,Pb和Cu含量增加达到了显著水平。它们在0.05显著水平的自相关距分别由3 500 m、3 300 m降低至2 700 m、2 800 m,呈递减趋势,空间随机性增强。土壤Pb和Cu的空间分布呈西高东低,并且在研究区绝大部分范围内出现不同程度的累积趋势。人为污染与干扰是土壤Pb和Cu含量增加与空间变异性增强的主要原因。

黄土丘陵小流域土壤物理性质的空间变异

黄土丘陵小流域土壤物理性质在景观尺度上的空间变异以质地、容重和饱和含水量最小,稳定入渗率最大,团稳性与粘结力居中。不同土地利用类型之间诸项物理性质都存在显著差异。土壤质地以林地的砂粒含量显著偏低但粉粒含量显著高于其它土地利用类型,休闲地的粉粒含量显著较低;容重以林地显著偏大,耕地较小;饱和含水量以灌木地较大,林地显著偏低;土壤团稳性以林地显著偏高,耕地显著偏低;土壤粘结力以灌木地、林地、荒地和休闲地显著较强,耕地显著较弱;稳定入渗率以灌木地显著较高,间作地显著较低。就坡形来说,垂直与水平凹形坡的砂粒含量都显著较低而粉粒含量比较高,相反直形坡的砂粒比较高而粉粒含量显著较低;饱和含水量与稳定入渗率都是以垂直直形坡较高,垂直凹形坡则较低。就坡向而言,偏东坡的土壤粘结力显著低于偏西坡;偏北坡土壤质地比偏南坡粘性强,但稳定入渗率低。稳定入渗率还随坡度的增大而增高。随着海拔的升高,土壤砂粒含量与稳定入渗率增高,而粘粒含量与团稳性呈降低趋势。

农田土壤特性的空间变异性及分形特征

对 2 4 m× 2 4 m面积内的 49个观测点进行了土壤含水量和坚实度的空间变异性研究。根据测定结果 ,用经典统计方法计算了均值、标准差、变异系数等统计特征值 ,认为该法不能定量的描述土壤特性的空间变异性。于是 ,用分形理论计算了含水量与坚实度的分形维数。结果表明 ,在一定范围内 ,土壤具有分形特征 。

塿土土壤水力特性空间变异的多重分形分析

为探讨塿土土壤水力特性的空间分布特征,对杨凌示范区大寨乡小麦与玉米轮作地进行直线分布土壤取样,室内测定了土壤水分特征曲线、饱和导水率、土壤含水率、容重等土壤水力特性,用Brooks-Corey模型对土壤水分特征曲线进行拟合,采用多重分形方法对Brooks-Corey模型参数(θs、α、n)、饱和导水率(Ks)、土壤含水率(θ)、容重(ρ)等进行空间变异性分析。结果表明:在全部采样方向上Ks、α及n的变异性较强,θs、θ及ρ表现为弱变异;不同采样方向上土壤水力特性参数具有多重分形特征;不同采样方向上θs、θ及ρ的多重分形结构较弱,空间变异性不强;不同采样方向上Ks、α及n的多重分形结构明显,广义分形维数分别为0.7～1.90、.6～1.2、0.9～1.1,空间变异性较强,且Ks比α和n具有更为复杂的空间分布结构。

半干旱草地土壤粒径分形维数及空间变异特征

本文以毛乌素沙区内半干旱草地土壤颗粒为研究对象,运用地质统计学方法分析土壤颗粒大小含量及其分形维数的空间变异性,认为分形维数与沙粒含量线性负相关,与粘黏粒含量线性正相关。土壤黏粉粒损失导致土壤沙化加剧,分形维数减少,说明分形维数可以反映土壤颗粒物质的损失状况及土壤沙质荒漠化的程度。在20m采样尺度上,各空间变量由随机因素引起的变异占总变异的比例较小,自相关引起的变异比例较大。以分形维数的空间变异性表示土壤质地的分布,不但方法简单且更经济实用。

粉煤灰充填复垦土壤理化性状研究

为了进一步搞清粉煤灰充填复垦构成的复垦土壤的理化性质,指导今后的复垦工作,通过选取不同时间、不同地点复垦土地的样点,采用室内外测试化验手段,对其进行了细致的研究.结果认为:复垦土壤入渗率小于农业土壤,土壤容重和土壤含水量大于农业土壤;复垦土壤pH值大于8,碱性过强.土壤有机质含量低,全氮含量低,速效磷含量低.全钾含量和速效钾含量充足.