共查询到19条相似文献，搜索用时 531 毫秒
1.
YANG Lin A-Xing ZHU ZHAO Yuguo LI Decheng ZHANG Ganlin ZHANG Shujie Lawrence E. BAND 《土壤圈》2017,27(2):344-357
High-resolution and detailed regional soil spatial distribution information is increasingly needed for ecological modeling and land resource management. For areas with no point data, regional soil mapping includes two steps: soil sampling and soil mapping. Because sampling over a large area is costly, efficient sampling strategies are required. A multi-grade representative sampling strategy, which designs a small number of representative samples with different representative grades to depict soil spatial variations at different scales,could be a potentially efficient sampling strategy for regional soil mapping. Additionally, a suitable soil mapping approach is needed to map regional soil variations based on a small number of samples. In this study, the multi-grade representative sampling strategy was applied and a fuzzy membership-weighted soil mapping approach was developed to map soil sand percentage and soil organic carbon(SOC) at 0–20 and 20–40 cm depths in a study area of 5 900 km2 in Anhui Province of China. First, geographical sub-areas were delineated using a parent lithology data layer. Next, fuzzy c-means clustering was applied to two climate and four terrain variables in each stratum. The clustering results(environmental cluster chains) were used to locate representative samples. Evaluations based on an independent validation sample set showed that the addition of samples with lower representativeness generally led to a decrease of root mean square error(RMSE). The declining rates of RMSE with the addition of samples slowed down for 20–40 cm depth, but fluctuated for 0–20 cm depth. The predicted SOC maps based on the representative samples exhibited higher accuracy, especially for soil depth 20–40 cm, as compared to those based on legacy soil data. Multi-grade representative sampling could be an effective sampling strategy at a regional scale. This sampling strategy, combined with the fuzzy membership-based mapping approach, could be an optional effective framework for regional soil property mapping. A more detailed and accurate soil parent material map and the addition of environmental variables representing human activities would improve mapping accuracy. 相似文献
2.
天然载体控释氮肥研究初探 总被引：2，自引：0，他引：2
The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%. 相似文献
3.
黄土高原沟壑区土壤侵蚀评价指标体系——以中国王东沟流域为例 总被引：19，自引：0，他引：19
The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%. 相似文献
4.
Neural network ensemble residual kriging application for spatial variability of soil properties 总被引：19，自引：0，他引：19
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. 相似文献
5.
Investigations into forest soils face the problem of the high level of spatial variability that is an inherent property of all forest soils. In order to investigate the effect of changes in residue management practices on soil properties in hoop pine （Araucaria cunninghamii Aiton ex A. Cunn.） plantations of subtropical Australia it was important to understand the intensity of sampling effort required to overcome the spatial variability induced by those changes. Harvest residues were formed into windrows to prevent nitrogen （N） losses through volatilisation and erosion that had previously occurred as a result of pile and burn operations. We selected second rotation （2R） hoop pine sites where the windrows （10-15 m apart） had been formed 1, 2 and 3 years prior to sampling in order to examine the spatial variability in soil carbon （C） and N and in potential mineralisable N （PMN） in the areas beneath and between （inter-） the windrows. We examined the implications of soil variability on the number of samples required to detect differences in means for specific soil properties, at different ages and at specified levels of accuracy. Sample size needed to accurately reflect differences between means was not affected by the position where the samples were taken relative to the windrows but differed according to the parameter to be sampled. The relative soil sampling size required for detecting differences between means of a soil property in the inter-windrow and beneath-windrow positions was highly dependent on the soil property assessed and the acceptable relative sampling error. An alternative strategy for soil sampling should be considered, if the estimated sample size exceeds 50 replications. The possible solution to this problem is collection of composite soil samples allowing a substantial reduction in the number of samples required for chemical analysis without loss in the precision of the mean estimates for a particular soil property. 相似文献
6.
自动土壤图基于知识的分类 总被引：7，自引：0，他引：7
A machine-learning approach was developed for automated building of knowledge bases for soil resources mapping by using a classification tree to generate knowledge from training data. With this method, building a knowledge base for automated soil mapping was easier than using the conventional knowledge acquisition approach. The knowledge base built by classification tree was used by the knowledge classifier to perform the soil type classification of Longyou County, Zhejiang Province, China using Landsat TM bi-temporal images and GIS data. To evaluate the performance of the resultant knowledge bases, the classification results were compared to existing soil map based on a field survey. The accuracy assessment mad maalysis of the resultant soil maps suggested that the knowledge bases built by the machine-learning method was of good quality for mapping distribution model of soll classes over the study area. 相似文献
7.
A GIS-based database management application package for fertilizer recommendations in paddy fields 总被引：10，自引：0，他引：10
Over-use of fertilizer in paddy fields could lead to agro-environmental pollution. Therefore, the Paddy Fertilizer Recommendation System (PFRS) application package was designed to aid in the dissemination of fertilizer recommendations for paddy fields. PFRS utilized geographical information system (GIS) ActiveX Controls, enabling the user to select a location of interest linked to a spatial database of paddy field soil characteristics. The application package also incorporated different soil fertilizer recommendation methods, forming a relational database. The application‘s structure conaiated primarily of building database queries using Standard Query Language (SQL) constructed during run-time, baaed on user provided spatial parameters of a selected location, the type of soil desired and paddy production criteria. PFRS, which was comprised of five modules including: File, View, Edit, Layer and Fertilizer/Model, provided the user with map-baaed fertilizer recommendations based on selected soil nutrient P and K map layers as well as N characteristica and land use maps. 相似文献
8.
普通克里格法在土壤有机碳制图中的应用 总被引：1，自引：0，他引：1
The quantification of the pattern and spatial distribution of soil organic carbon (SOC) is fundamental to understand many ecosystem processes.This study aimed to apply ordinary kriging (OK) to model the spatial distribution of SOC in a selected part of Zambia.A total of 100 soil samples were collected from the study area and analyzed for SOC by determining soil oxidizable carbon using the Walkley-Black method.An automated fitting procedure was followed when modeling the spatial structure of the SOC data with the exponential semivariogram.The results indicated that the short range spatial dependence of SOC was strong with a nugget close to zero.The spatial autocorrelation was high to medium with a nugget to sill ratio of 0.25.The root mean square error of the predictions was 0.64,which represented 58.18％ of the mean observed data for SOC.It can be concluded that the generated map could serve as a proxy for SOC in the region where evidence of spatial structure and quantitative estimates of uncertainty are reported.Therefore,the maps produced can be used as guides for various uses including optimization of soil sampling. 相似文献
9.
Yazhou SUN Wenxuan GUO David C. WEINDORF Fujun SUN Sanjit DEB Guofeng CAO Jasmine NEUPANE Zhe LIN Abir RAIHAN 《土壤圈》2021,31(5):705-714
Excess calcium(Ca) in soils of semi-arid and arid regions has negative effects on soil structure and chemical properties, which limits the crop root growth as well as the availability of soil water and nutrients. Quantifying the spatial variability of soil Ca contents may reveal factors influencing soil erosion and provide a basis for site-specific soil and crop management in semi-arid regions. This study sought to assess the spatial variability of soil Ca in relation to topography, hydraulic attributes, and soil types for precision soil and crop management in a 194-ha production field in the Southern High Plains of Texas,USA. Soils at four depth increments(0–2, 0–15, 15–30, and 30–60 cm) were sampled at 232 points in the spring of 2017. The Ca content of each sample was determined with a DP-6000 Delta Premium portable X-ray fluorescence(PXRF) spectrometer. Elevation data was obtained using a real-time kinematic GPS receiver with centimeter-level accuracy. A digital elevation model(DEM) was derived from the elevation data, and topographic and hydraulic attributes were generated from this DEM. A generalized least-squares model was then developed to assess the relationship between soil Ca contents of the four layers and the topographic and hydraulic attributes. Results showed that topographic attributes, especially slope and elevation, had a significant effect on soil Ca content at different depths(P 0.01). In addition, hydraulic attributes, especially flow length and sediment transport index(STI), had a significant effect on the spatial distribution of soil Ca. Spatial variability of soil Ca and its relationships with topographic and hydraulic attributes and soil types indicated that surface soil loss may occur due to water or wind erosion, especially on susceptible soils with high slopes. Therefore, this study suggests that the application of PXRF in assessing soil Ca content can potentially facilitate a new method for soil erosion evaluation in semi-arid lands. The results of this study provide valuable information for site-specific soil conservation and crop management. 相似文献
10.
土地混合使用制度下土壤硝态氮分布的地理空间制图研究 总被引：5，自引：0，他引：5
Mapping the spatial distribution of soil nitrate-nitrogen (NO3-N) is important to guide nitrogen application as well as to assess environmental risk of NO3-N leaching into the groundwater. We employed univariate and hybrid geostatistical methods to map the spatial distribution of soil NO3-N across a landscape in northeast Florida. Soil samples were collected from four depth increments (0-30, 30-60, 60-120 and 120-180 cm) from 147 sampling locations identified using a stratified random and nested sampling design based on soil, land use and elevation strata. Soil NO3-N distributions in the top two layers were spatially autocorrelated and mapped using lognormal kriging. Environmental correlation models for NO3-N prediction were derived using linear and non-linear regression methods, and employed to develop NO3-N trend maps. Land use and its related variables derived from satellite imagery were identified as important variables to predict NO3-N using environmental correlation models. While lognormal kriging produced smoothly varying maps, trend maps derived from environmental correlation models generated spatially heterogeneous maps. Trend maps were combined with ordinary kriging predictions of trend model residuals to develop regression kriging prediction maps, which gave the best NO3-N predictions. As land use and remotely sensed data are readily available and have much finer spatial resolution compared to field sampled soils, our findings suggested the effcacy of environmental correlation models based on land use and remotely sensed data for landscape scale mapping of soil NO3-N. The methodologies implemented are transferable for mapping of soil NO3-N in other landscapes. 相似文献
11.
以英国Hillsborough农业研究所附近的一块7.9 hm2的牧草地为研究区，采用地统计的半方差分析和克立格方法研究其空间变异性和空间插值。同时对研究田块的样点根据不同间距、不同形状进行删选，对不同布局状况下的结果进行统计比较，以获取满足一定精度下的最少采样个数和采样形状。研究结果表明，单纯利用样方统计，土壤有效钾需要65个采样点，大致为原始采样点的一半。而在考虑空间采样形状和空间插值效果，再采用最小显著性差异（LSD）进行比较，该田块土壤有效钾采样最好使用规则三角网布点（样点数为62个）。 相似文献
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13.
基于传统土壤图的土壤—环境关系获取及推理制图研究 总被引：3，自引：0，他引：3
在数字土壤制图研究中,从历史资料中提取准确的、详细的土壤—环境关系对于土壤图的更新和修正十分重要。从传统土壤图中提取土壤类型并从地形数据中提取环境参数,采用空间数据挖掘方法建立土壤—环境关系,并进行推理制图和精度验证。以湖北省黄冈市红安县华家河镇滠水河流域为例,首先选取成土母质和基于地形数据提取的高程、坡度、坡向等7个环境因子;然后利用频率分布原理得到包含土壤类型与环境因子信息的典型样本数据1 410个;采用See5.0决策树方法进行空间数据挖掘,建立土壤—环境关系;将其导入So LIM中进行推理制图;最后利用270个实地采样点验证所得土壤图的精度。土壤图的精度提高了约11%,证明了本研究方法对土壤类型和空间分布推理的可靠性。 相似文献
14.
土壤钾素空间变异性和空间插值方法的比较研究 总被引：14，自引：0，他引：14
通过研究土壤养分的空间变异性和空间插值方法 ,获取田间土壤养分的连续分布图是当前精确施肥技术的工作基础。本研究以英国Hillsborough农业研究所附近的一块 7.9hm2 的牧草田为研究区 ,区内以 25m25m网格点采样 ,共 125个采样点。以土样的钾素含量为研究对象 ,采用移动平均、趋势面拟合、样条插值、点状克立格、逆距离加权等各种空间插值方法对一部分离散的采样点进行连续插值而获取土壤钾素空间分布图。同时以另一部分的采样点数据来对各种插值方法的结果进行均差和均方差的比较分析。研究结果表明 ,克立格、逆距离加权两种方法总体效果最好 ,其中克立格方法中又以指数模型为佳 ,逆距离加权插值法以二次方为佳 相似文献
15.
不同采样设计会对土壤呼吸空间变异特征的预测精度产生重要影响。本研究选取黄淮海平原北部潮土区1 km×1 km夏玉米样地,在7×7单元规则格网(样点间距167 m)、完全随机(样点平均间距433 m)以及3×3单元规则格网+完全随机(样点平均间距405m)3种布点方式的基础上,保持样本总量(49)不变,以占总样点2%～14%的短距离样点(样点间距4m)随机替换原方案相应样点个数的方法优化布点方式,应用普通克里金法插值,以均方根误差(RMSE)和确定系数(R2)作为验证指标,检验基于3种布点方式设置的短距离样点对土壤呼吸空间变异预测精度的影响。结果表明:研究区土壤呼吸平均速率为2.65μmol·m?2·s?1,空间分布均呈西高东低,表现出中等程度变异。采样设计对土壤呼吸空间分布的预测精度影响显著,基于3种布点方式设置短距离样点可提高预测精度7%～13%。无短距离样点替换时,规则格网+完全随机的布点方式最优,比完全随机布点和规则格网布点的空间插值预测精度分别提高10%和22%;设置短距离样点替换后,在最优布点方式(规则格网+完全随机)中,对土壤呼吸空间变异的预测精度可再提高4%～7%,其中短距离样点个数占样本总量10%对土壤呼吸空间变异预测精度的提高最为明显。研究发现,基于相同的样本数量设置短距离样点可增加区域范围内样点密度,提高土壤呼吸空间变异预测精度及试验结果的可靠性。因此,在黄淮海平原北部潮土区100 hm2尺度的夏玉米样地中,规则格网+完全随机+10%短距离样点的布点方式是预测土壤呼吸空间变异最适宜的采样布点方式。 相似文献
16.
土壤钾素空间变异性和空间插值方法的比较研究 总被引：14，自引：0，他引：14
通过研究土壤养分的空间变异性和空间插值方法 ,获取田间土壤养分的连续分布图是当前精确施肥技术的工作基础。本研究以英国Hillsborough农业研究所附近的一块 7.9hm2 的牧草田为研究区 ,区内以 25m×25m网格点采样 ,共 125个采样点。以土样的钾素含量为研究对象 ,采用移动平均、趋势面拟合、样条插值、点状克立格、逆距离加权等各种空间插值方法对一部分离散的采样点进行连续插值而获取土壤钾素空间分布图。同时以另一部分的采样点数据来对各种插值方法的结果进行均差和均方差的比较分析。研究结果表明 ,克立格、逆距离加权两种方法总体效果最好 ,其中克立格方法中又以指数模型为佳 ,逆距离加权插值法以二次方为佳 相似文献
17.
详细的土壤空间与属性的信息已成为环境模型和土地管理的基本参数,传统的以类别多边形和手工编制为基础的传统土壤制图效率低精度也较差。本文基于GIS、模糊逻辑和专家知识,建立了土壤一环境推理模型(SoLIM),通过基于土壤一环境关系模型的土壤相似度模型与对该模型进行赋值的推理技术来编制土壤图,从而克服了传统土壤制图中的简化。通过两个小区的研究表明,与传统土壤制图相比,通过SoLIM得出的土壤信息在空间详细度和属性精确度都有较大的提高,也能够大量减少调查的时问和经费,从而大大提高土壤调查的效率。SoLIM方法在我国推广十分必要且具有一定的条件,但仍需要进一步完善。 相似文献
18.
基于数据挖掘模型的土壤图更新是一项重要的研究。数据挖掘模型构建中训练样点的质量不仅决定其对研究区土壤-环境关系表达的充分程度,而且会对推理制图的结果产生至关重要的影响。本文提出一种基于土壤类型面积分级的典型训练样点选择方法,即依据土壤面积对土壤类型分级,并按照等级之间的比例关系基于典型点选择训练样点。将方法应用于更新美国威斯康星州Raffelson流域的传统土壤图,并与另外两种训练样点选择方法对比,以验证该方法的有效性。结果表明,500次重复实验中,本研究方法与另外两种训练样点选择方法相比,能够更新传统土壤图的比例分别为79.5%、71.8%和63.6%,而且其推理制图结果更符合研究区土壤分布的特征。本研究所提方法是一种有效的训练样点选择方法。 相似文献