Fuzzy mathematical methods for soil survey and land evaluation

The rigid-data model consisting of discrete, sharply bounded internally uniform entities that is used in hierarchical and relational databases of soil profiles, choropleth soil maps and land evaluation classifications ignores important aspects of reality caused by internal inhomogeneity, short-range spatial variation, measurement error, complexity and imprecision. Considerable loss of information can occur when data that have been classified according to this model are retrieved or combined using the methods of simple Boolean algebra available in most soil and geographical information systems. Fuzzy set theory, which is a generalization of Boolean algebra to situations where data are modelled by entities whose attributes have zones of gradual transition, rather than sharp boundaries, offers a useful alternative to existing methodology. The basic principles of fuzzy sets, operations on fuzzy sets and the derivation of membership functions according to the Semantic Import Model are explained and illustrated with data from case studies in Venezuela and Kenya.     

Assessing suitability of different extractants for determining available boron in soil

In the present study, the extractability of available Boron (B) by different extractants was tested in relation to soil properties. Soil samples from different parts of Indo-Gangetic flood plains of West Bengal were collected and available B extracted with various extractant viz. hot calcium chloride (CaCl₂) (HCC), Potassium di-hydrogen phosphate (PDP), tartaric acid (TA) and MCC. Plant availability of B was assessed by growing wheat (Triticum aestivum L.cv.K-1006) in such soils through pot experiments. HCC showed the highest available B content as well as highest correlation coefficient value with all plant growth parameters and soil properties. The B extracting efficiency of the tested extractants was found in the order of HCC > PDP > TA > MCC. Results showed that dry matter yield, plant B concentration and uptake was increased significantly after application of Borax. Linear Correlations, Multiple regression analysis using Mallow's Cp statistics proved HCC to be the best extractant for estimating available B in experimental soils.     

可变模糊集方法及其在土地适宜性评价中的应用

土地适宜性是多级别、多指标模糊评价问题,其模糊性在评价中应予以考虑。可变模糊集方法以可变模糊集理论为基础,通过模型参数的变化,提高评价结果的可靠性。该文在介绍该方法的基础上对长乐市农用土地适宜性等级进行了评价。结果表明该市农用土地适宜性等级介于中度适宜与高度适宜之间,略偏于中度适宜。可见该方法在土地适宜性评价中具有较好的适用性。     

土壤水分剖面测量系统设计与应用性能检验

针对农田环境下观测不同作物根区土壤水分变化的实际需要,研制了一种可快速获取0～200 cm深度范围内土壤剖面含水率的传感器及其测量系统。其中水分传感器工作原理为基于电容边缘场效应测量电极周围介质的介电常数,与土壤接触采用PVC套筒式结构,深度测量为霍尔磁敏传感器阵列,测量系统数据处理平台为PDA。对于测量方法的理论研究,该文给出了传感器工作原理的解析分析,进一步提出了传感器应用性能检验的试验方法。结果表明,该传感器性能指标达到实际应用需求,具备应用推广价值。     

土壤热参数确定方法比较与修正

土壤热参数是分析研究土壤热传递的基本参数,寻求确定热参数简单方法是研究的热点问题.该文利用自行研制的土壤热特性试验系统,测定了4种质地土壤热特性,计算了不同质地土壤在不同含水率、不同容重情况下的热扩散率,进一步推导出不同情况下的导热率,并与Campbell经验公式计算的导热率进行比较,发现计算值与实测值相差较大,并对Campbell经验公式进行修正,同时对修正经验公式进行分析、检验,并讨论此经验公式的适用范围.结果显示在体积含水率小于20%的时候,修正经验公式可以用于计算导热率.     

Methods to interpolate soil categorical variables from profile observations: Lessons from Iran

The paper compares semi-automated interpolation methods to produce soil-class maps from profile observations and by using multiple auxiliary predictors such as terrain parameters, remote sensing indices and similar. The Soil Profile Database of Iran, consisting of 4250 profiles, was used to test different soil-class interpolators. The target variables were soil texture classes and World Reference Base soil groups. The predictors were 6 terrain parameters, 11 MODIS EVI images and 17 physiographic regions (polygon map) of Iran. Four techniques were considered: (a) supervised classification using maximum likelihoods; (b) multinominal logistic regression; (c) regression-kriging on memberships; and (d) classification of taxonomic distances. The predictive capabilities were assessed using a control subset of 30% profiles and the kappa statistics as criterion. Supervised classification and multinominal logistic regression can lead to poor results if soil-classes overlap in the feature space, or if the correlation between the soil-classes and predictors is low. The two other methods have better predictive capabilities, although both are computationally more demanding. For both mapping of texture classes and soil types, the best prediction was achieved using regression-kriging of indicators/memberships (κ = 45%, κ = 54%). In all cases kappa was smaller than 60%, which can be explained by the preferential sampling plan, the poor definition of soil-classes and the high variability of soils. Steps to improve interpolation of soil-class data, by taking into account the fuzziness of classes directly on the field are further discussed.     

酸性土壤有机碳两种测定方法的比较

土壤有机质虽然占矿质土壤总量的比例很小,但对土壤质量及功能的调节起着关键作用。因此,寻求合适的土壤有机碳测定方法十分重要。本研究以4个长期定位试验(A、B、C、D)为基础,在灵敏度、相关性等方面对外加热法和碳氮仪法作了比较。结果表明:对于酸性土而言无论测定整土还是团聚体有机碳,两种方法的准确度和灵敏度都很高,但外加热法能更灵敏地反应处理间的差异性;两种方法测定结果有很好相关性,但碳氮仪法测定结果较外加热法偏高;由于测定结果存在差异,在科研工作中两种方法不能混用,以免得出错误结论。     

土壤有机质速测方法的比较与研究

不同速测方法均具有较好的快速性和重现性 ,以水合热 -比色法精度最好 ,并适用于不同土壤 ;但碱液浸提 -比色法有较好的实用性。外加热有助于提高浸提能力并减少气温对浸提过程的干扰 ;不同土壤对碱液浸提 -比色法的适应性不同 ;改进浸提液、并在测试过程中添加标准土样做比较有助于进一步修正精度 ,可以满足划分地力等级的精度要求     

Developing scoring functions for soil quality to assess land suitability for irrigated wheat in Southern Algeria

Efficient land-use management could be optimized through appropriate advice regarding land suitability and achieving a reasonable yield while preserving soil and environmental conditions. The main objective of this study was to determine and define those locations capable of wheat cultivation with irrigation in the municipality of N’goussa (Southern Algeria). Expert opinion (EO) method was used for selecting minimum soil data set (MDS_-EO), where six influencing soil properties (sand, pH, salinity, organic matter, gypsum and lime) and other three key parameters (slope, land use/land cover, and proximity to roads and electricity network) were considered important for irrigated wheat cultivation in the study area. Indicators were weighted according to principal component analysis (PCA) loadings and summed. PCA revealed that the selected nine indicators are appropriate for accounting 73.63% of the total variance. Two maps of land suitability were created here (expressed as a soil quality index within a range from 0 to 1) from multivariate analysis and already known standard scoring functions (SSFs) by using two data sets (pure and scored). The distribution of soil quality index (IQI) showed that above 70% of the land was moderately (MS) to highly suitable (HS) for irrigated wheat. The estimation accuracy of soil quality classes has been evaluated using random forests (RF), having as a dependent variable the final class of land suitability used in each map. It was determined that estimation accuracy could reach 60% (pure data set) and 65% (scored data set) at 0.5 cut-off value for soil quality classes. Final prioritizing according to ranks of sensitivity index (SI) and efficiency ratio (ER) showed that IQI obtained from scored data set is the most suitable approach in soil quality assessment of arid areas. Therefore, it could be applied in southern Algeria for land management, integrated planning and environmental assessments.     

Comparison of soil phosphorus extraction methods regarding their suitability for organic farming systems

Background

Organic farmers frequently report sufficient yield levels despite low or even very low soil phosphorous (P) contents questioning the applicability of widely used laboratory methods for soil P testing for organic farming.

Aims

The aim of this study was to compare the validity of a broad range of different soil extraction methods on soils under organic management from South West Germany and to test the correlation of the measured soil P concentration with plant offtake.

Methods

Twenty-two soil samples of eight different organic farms were extracted with different solutions: (1) water, (2) CAL, (3) Olsen, (4) Mehlich 3, (5) Bray P1, (6) Bray P2, (7) NaOH+Na₂EDTA, and (8) total P. The results were then correlated with above ground plant P.

Results

Spearman's rank correlation coefficient (r_s) of correlations between above ground plant P and extractable soil P (Water-P, CAL-P, and Olsen-P [+active charcoal {+AC}]) determined with ICP-OES were strong (0.94, 0.90, and 0.93, respectively). Among the tested methods, above ground plant P showed a strong correlation with CAL-P as detected by ICP-OES (r_s = 0.90) and colorimetry (r_s = 0.91). The comparison of CAL-P data provided by farmers and CAL-P analyzed during this research showed discrepancies between the results.

Conclusions

The results of this study indicate that the CAL method can be used in organic farming despite a low extraction of organic P (P_org). Furthermore, it is recommended for farmers to take soil samples for analyses regularly and interpret changes in P in the long-term instead of interpreting individual samples.     

盘式吸渗仪测定土壤导水率的两种新方法

应用盘式吸渗仪测定田间土壤导水率具有快速简单的优点，但是测定结果的计算处理比较繁琐，寻求简单的计算方法是广泛应用盘式吸渗仪的关键问题。该文改变盘式吸渗仪测定土壤导水率的三维入渗过程为一维入渗过程，简化了测定结果的计算处理。结果显示：两种不同的一维入渗过程达到的稳定入渗率和导水率之间有很好的线性关系，但是三维过程计算的导水率大于一维过程。双套盘吸渗仪一维过程计算导水率与稳定入渗率一致性较好，但是和三维稳态、瞬态方法计算结果之间差异明显，因此在应用这些方法时需要适当调整参数，建议使用双套盘吸渗仪快速测定田间土壤导水率。     

Critical evaluation of methods for determining total protein in soil solution

Proteins represent a significant reservoir of organic nitrogen in most terrestrial ecosystems and therefore comprise a key component of the soil N cycle. Consequently, there is a critical need to develop robust methodologies for quantifying the abundance of proteins in soil. In this study we evaluated the performance of five commercially available total protein assay kits in a contrasting range of soils. All the kits were based on the detection of proteins after conjugation with either chromophores or fluorophores. Overall, we found that all the kits suffered significant signal interference from humic substances present in solution, resulting in either a quenching or enhancement of the protein response. Inter-comparison of the kits yielded no agreement when quantifying the total amount of protein present in soil solution, with differences in concentration for individual samples ranging 20–500-fold when using the different assay kits. We concluded that none of the commercial assay kits can provide a reliable indicator of soil solution protein content. Although it may detect some non-proteinaceous material (e.g. peptidoglycan), total protein quantitation is currently best undertaken by acid hydrolysis of proteins in solution with subsequent determination of the amino acids liberated. However, there is an imperative need to develop robust methods for protein extraction, purification and analysis in soil.     

Romanian experience with land classification related to soil tillage

Soil, climate and relief criteria to select the most adequate soil tillage methods are discussed. Using these criteria, a general scheme showing special requirements for various tillage systems is presented. Classifications of soils according to specific draught resistance for ploughing and to compaction problems are discussed, as are special schemes related to the selection of soils requiring deep ripping, soil suitability for minimum tillage, or soil suitability for fully mechanized harvesting of potatoes. Areas of croplands in Romania, classified according to each of the classification schemes discussed, are estimated.     

A land suitability assessment for tropical forage legumes

Land suitability assessments for forage legume production (genera Stylosanthes, Centrosema, and Desmodium) for 21 Hawaii soils were obtained by using a land suitability classification based on Soil Taxonomy. Land assessments based on four qualities, viz., nutrient availability, water availability, soil acidity and soil thermal regime, indicated that six of the soils were unsuitable for forage legume production without application of agricultural inputs (fertilizer, lime, and irrigation). Nutrient availability was the land quality that most frequently failed to meet the requirements of tropical forage legumes. Application of low levels of input reduced the number of unsuitable soils from six to three, whereas high inputs made all soils suitable for forage legume production. The land suitability assessments were consistent with published field results on forage legume performance in Hawaii. The results suggest that quick and reliable estimates of land use for forage legume production can be obtained wherever Soil Taxonomy is used in available surveys.     

基于农用地分等和土壤环境质量评价的耕地综合质量评价

该文从耕地生态管护的角度出发,探讨了如何实现土壤环境质量评价与农用地分等成果的融合。基于土壤环境质量评价和农用地分等的理论和方法,该文提出了耕地综合质量评估技术,即在农用地分等所建立的等级体系基础上,引入土壤环境质量评价系数概念,进一步利用该系数对农用地利用等指数进行修订,得到耕地综合评价指数,并以河南省洛阳市为例作了实证研究。根据洛阳市耕地质量综合评价结果,与原农用地利用等别相比,无污染的耕地综合等别保持不变,有污染倾向的耕地综合等别有所下降,存在污染的耕地等别降为末等。这些评价结果可以为土地利用管理、环境污染防治规划将提供更有效的依据。     

Integration of ANP and Fuzzy set techniques for land suitability assessment based on remote sensing and GIS for irrigated maize cultivation

Land suitability assessment can inform decisions on land uses suitable for maximizing crop yield while making best use, but not impairing the ability of natural resources such as soil to support growth. We assessed the suitability of maize to be produce in 12,000 ha land of Dasht-e-Moghan region of Ardabil province, northwest of Iran. Suitability criteria included soil depth, gypsum (%), CaCO₃ (%), pH, electrical conductivity (EC), exchangeable sodium percentage (ESP), slope (%) and climate data. We modified and developed a novel set of techniques to assess suitability: fuzzy set theory, analytic network process (ANP), remote sensing and GIS. A map of suitability was compared a map created using a traditional suitability technique, the square root method. The coefficient of determination between the land suitability index and observed maize yield for square root and ANP-fuzzy methods was 0.747 and 0.919, respectively. Owing to greater flexibility to represent different data sources and derive weightings for meaningful land suitability classes, the ANP-fuzzy method was a superior method to represent land suitability classes than the square root method.     

杜马斯燃烧法和凯氏定氮法在土壤全氮检测中的比较研究

选用 6组不同全氮含量的土壤样品(梯度为 0%～0.06%、0.06%～0.1%、0.1%～0.2%、0.2%～0.3%、0.3%～ 0.4%和 0.4%～ 0.5%)和 4份土壤有效态成分分析标准物质为试验材料,分别采用杜马斯燃烧法和凯氏定氮法测定其全氮含量,并对两种方法测定结果的精密度、准确度和相关性及检测成本进行了比较分析。对土壤有效态成分分析标准物质全氮含量的检测,两种方法测定结果都接近于真实值,比较两种方法的相对标准偏差(RSD)和相对误差(RE)值,可确定杜马斯燃烧法精密度更高,且准确度更好;对于含氮量范围为 0%～ 0.06%的样品,两种方法的测定值之比(D/K)为 0.692～ 0.965,杜马斯燃烧法测定结果的变异系数为 0.00%～ 9.96%,测定结果不稳定,两种方法的测定值间存在显著的线性相关,但 R2仅为 0.9049;而含氮量大于 0.06%的样品,两种方法的测定值之比(D/K)为 0.940～ 1.104,变异系数均小于 5%,测定结果间存在显著的线性相关(R2=0.9979)。在检测成本方面,完成相同数量样品检测,杜马斯燃烧法所需时间和人力都约是凯氏定氮法的1/2。因而,杜马斯燃烧法是一种环保、高效的土壤全氮检测方法,对于含氮量范围为 0%～ 0.06%的土壤样品,凯氏定氮法的测定结果更接近于真实值,而对于含氮量大于 0.06%的土壤样品,杜马斯燃烧法更加适用。     

Prediction of profile soil moisture for one land use using measurements at a soil depth of other land uses in a karst depression

Purpose

Information on root-zone soil water content (SWC) is essential for vegetation restoration, irrigation scheduling, and hydrological modeling. However, measurements of SWC within a variety of land uses may be time-consuming and labor-costing. This study tested whether SWC at a depth of a land use can be used to predict profile SWC of other land uses in terms of temporal stability analysis at a karst depression area in southwest China.

Materials and methods

A total of 30 datasets of root-zone SWC from 0.1- to 0.5-m depths were collected by time domain reflectometry probes for three typical land uses from March 12 to November 8, 2015.

Results and discussion

Results showed that the profile mean SWC and its associated standard deviation (SD_P) and coefficient of variation (CV_P) differed significantly (P?<?0.05) among the grassland, farmland, and forestland. The profile SWC was more temporally stable according to the apparently lower CV_T in comparison with CV_P. The similarities of the vertical patterns of SWC were strong for the same land uses, while were relatively weak between the different land uses. The SWC measurements of the most temporally stable depth can be used to accurately predict profile SWC for both the same land use and other land uses.

Conclusions

This study further expands the application of the temporal stability analysis and can aid water resource management in areas with diverse land uses.

     

粮田改种蔬菜后土壤剖面硝态氮的动态变化

对不同种植方式下0～4m土层硝态氮(NO-3-N)累积状况的比较研究表明,粮田改种蔬菜后NO-3-N被迅速淋洗到2m以下土层;淋洗到下层的NO-3-N累积量随种菜时间的延长而不断增加;蔬菜地约41%～50%的NO-3-N累积在2～4m土层,粮田约95%NO-3-N累积在0～2m土层,其差异是由于施肥方式、灌水量和作物吸收程度的不同所致.     

红壤不同利用方式下的剖面酸度特征

【目的】 作物类型及其管理模式是影响红壤酸化的主要因素之一,研究不同利用方式下红壤剖面酸度的变化特征,对红壤酸化防治具有重要指导意义。 【方法】 选取由红砂岩母质发育红壤的4种主要利用方式 (水田、旱地、果园和林地),通过分层 (0—20、20—40、40—60、60—80 cm和80—100 cm) 测定pH、交换性酸、交换性盐基总量和盐基饱和度,定量比较不同利用方式下各酸度指标在剖面上的变化特征及程度。 【结果】 在不同利用方式下,红壤剖面pH为水田 (5.69) > 旱地 (4.71) ≈ 果园 (4.74) > 林地 (4.49);交换性酸含量为林地 (6.54 cmol/kg) ≈ 旱地 (6.52 cmol/kg) > 果园 (3.51 cmol/kg) > 水田 (0.79 cmol/kg);交换性盐基总量为水田 (4.47 cmol/kg) > 旱地 (1.97 cmol/kg) > 果园 (1.26 cmol/kg) > 林地 (0.48 cmol/kg);盐基饱和度为水田 (53.14%) > 旱地 (20.87%) > 果园 (15.41%) > 林地 (4.67%)。随着土层深度的增加,红壤剖面pH值逐渐升高;不同层次间交换性酸含量无显著差异;交换性盐基总量随土壤深度增加逐渐升高,为60—100 cm (2.34 cmol/kg) > 40—60 cm (2.05 cmol/kg) > 0—40 cm (1.75 cmol/kg);水田利用方式下红壤盐基饱和度随土壤深度增加逐渐升高,为80—100 cm (33.95%) > 60—80 cm (32.27%) > 40—60 cm (31.31%) > 20—40 cm (25.47%) > 0—20 cm (21.08%)。水田、果园利用方式下红壤pH与交换性酸含量呈显著负相关,与交换性盐基总量和盐基饱和度呈显著正相关;旱地利用方式下红壤pH与交换性盐基总量呈显著正相关;林地利用方式下pH与交换性酸含量呈显著负相关。 【结论】 4种利用方式下,在0—40 cm土层,林地红壤酸度最高,其次是果园和旱地,水田红壤酸度最低,在40—100 cm土层酸度变异较小。通过改变土地利用方式,降低红壤交换性酸含量、增加交换性盐基总量和盐基饱和度可以有效降低红壤酸度。