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.     

Soil Quality Assessment Through Minimum Data Set Under Different Land Uses of Submontane Punjab

Soil quality degradation is a major challenge in submontane Punjab. This poses a great threat to soil quality of this particular area. Thus, a study was conducted to address the selection of most appropriate soil quality indicators and to know the status of soil quality in the area under different land uses. Principal component analysis (PCA) approach was employed to get the minimum data set. Geo-referred soil samples were collected from five different land uses and analyzed for different physical, chemical, and biological attributes. The PCA was performed which screened out the five principal components (PCs) with eigenvalue >1. Soil quality index was highest under the land use forest (0.80) followed by grasses (0.79), horticulture (0.78), cultivated (0.75), and bare (0.67). The organic carbon contributed maximum to soil quality (28.5%) followed by available K (19.4%), electrical conductivity (18.3%), K-factor of universal soil loss equation (USLE) (14.9%), plant available water (10.5%), and clay (8.3%). Conclusively, the study area falls under the medium category of soil quality.     

伊朗东北部的农业和牧场土壤孔隙大小分布作为土壤物理质量指标

Assessment of soil quality is important for optimum production and natural resources conservation. Agricultural and pasture soil qualities of Deh-Sorkh region located at south of Mashhad, northeastern Iran were assessed using the integrated quality index (IQI) and Nemero quality index (NQI) models in combination with two datasets, i.e., total data set (TDS) and minimum data set (MDS). In this study 6 soil properties considered as MDS were selected out of 18 properties as TDS using principle component analysis. Soil samples were divided into 3 groups based on optimum ranges of 8 soil physical quality indicators. Soil samples with the most indicators at optimum range were selected as group 1 and the samples having fewer indicators at optimum range were located in groups 2 and 3. Optimum ranges of soil pore size distribution functions were also determined as soil physical quality indices based on 8 soil physical quality indicators. Pore size distribution curves of group 1 were considered as the optimum pore size functions. The results showed that relatively high organic carbon contents could improve pore size distribution. Mean comparisons of soil physical quality indicators demonstrated that mean weight diameter of wet aggregates, structural stability index, the slope of moisture retention curve at inflection point, and plant available water content in agricultural land use decreased significantly in relation to pasture land use. In addition, the results demonstrated that the studied MDS could be a suitable representative of TDS. 78% of pasture soils had the optimum pore size distribution functions, while this parameter for agricultural soils was only 13%. In general, the soils of the studied region showed high limitations for plant growth according to the studied indicators.     

基于最小数据集的青藏公路沿线土壤质量评价

为明确青藏公路沿线土地土壤质量的基本特征,通过采集沿线3种不同土地利用类型(农地、草地和沙地)的土壤样品,采用主成分分析法(PCA,Principal Component Analysis)筛选最小数据集(MDS,Minimum Data Set)指标,并构建土壤质量指数(SQI,Soil Quality Index)定量评价其土壤质量。结果表明:(1)相较于农地和草地,沙地的土壤肥力较为贫瘠,其土壤有机质、全氮和有效磷的土壤肥力等级均为6级。9个土壤指标均为中低度敏感指标,沙地土壤黏粒和粉粒含量具有更强的空间分异性。(2)沿线土壤质量评价最小数据集由全钾、全磷、有机质、黏粒和粉粒组成,最小数据集能够较好地替代全数据集进行土壤质量评价(p<0.01)。(3)沿线农地的土壤质量指数SQI(0.535±0.043)高于草地SQI(0.499±0.044)和沙地SQI(0.449±0.066)。该研究发现沿线农地土壤质量为中等水平,沿线草地和沿线沙地土壤质量处于较低水平,土壤有机质是影响青藏公沿线土壤质量的主要因素。     

Winter wheat (Triticum aestivum L.) growth potential in the Slovak rural landscape

By the application of geographic information system (GIS) based on existing databases on soil characteristics, it is possible to quantify and assess categories of soil suitability important for crop cultivation. In this article we demonstrate such methods for winter wheat. The objective was to differentiate the Slovak rural landscape with respect to the possibility of effective winter wheat cultivation. The differentiation was based on soil climatic and production economic parameters. For soil categorization, correlation relationships between the site properties (soil and climatic conditions) and crop biological and agro-technical requirements were considered. The prediction was subsequently interpolated into four suitability categories: soils not suitable for wheat cultivation, less suitable soils, suitable soils, and very suitable soils. The database was developed and each area was added to it as well as the particular category of suitability for wheat cultivation. By using the GIS distribution in Slovakia, the maps of soil suitability categories for wheat cultivation were generated. In Slovakia, 29% of farmland was found to be very suitable for wheat cultivation, 25% suitable, 9% less suitable and 37% non-suitable by our calculations. These categories are characterized in detail and specified from the point of view of geographic, soil, climatic, production, economic and energetic parameters.     

基于生态生产生活视角的北方农牧交错区土地宜耕性评价

北方农牧交错区是中国生态脆弱地区,土地荒漠化问题突出,土地利用是导致土地荒漠化的主要原因。生态文明建设背景下,研究该区域土地宜耕性对促进该地区生态环境保护和土地资源科学利用具有重要意义。该文以位于北方农牧交错区的科尔沁左翼后旗为例,基于生态、生产、生活的视角,构建评价指标体系对土地宜耕性进行评价,表明,现状耕地中不适宜耕作的耕地面积为15 996.87 hm~2,占耕地总面积的5.339%,因生态、生产、生活因素使得耕地不适宜耕作的面积分别为7 519.23、9 337.23、6 039.99 hm~2。建议在退耕还林工程中优先对该部分耕地进行退耕。适宜耕作的草地面积为197 195.94 hm~2,占草地总面积的32.18%,即有三分之一左右的草地可以开发利用为耕地。但是,从土壤适宜性和地形条件两方面对适宜耕作的草地进行分析,揭示出适宜耕作的优质草地面积比例很小。为避免土地开发利用导致农牧交错区生态环境的破坏和荒漠化的扩张,建议在跨省域耕地占补平衡中应当优先开发利用质量较高的耕地后备资源,且需始终坚持国家统筹。     

Soil quality assessment under shifting cultivation and forests in Northeastern Himalaya of India

The study aimed to evaluate the impact of shifting cultivation on soil quality, in Wokha district of Nagaland, using weighted soil quality index (SQIw). Four forest sites and three sites under shifting cultivation were selected and physical (texture and bulk density) and chemical (pH, electrical conductivity, cation exchange capacity, organic carbon, available N, P, K, exchangeable cations) parameters were analyzed. The SQIw was calculated on a minimum data set selected by principal component analysis, followed by varimax rotation algorithm and through subsequent normalization of the parameters using the linear scoring function. Significant (P < 0.05) variations in SQIw were found across the depth of the soil and land use according to severity of factors associated with land use. Three different classes of soil quality were also identified: high quality (SQIw > 0.70) for two forest soils (FS1 and FS2) and land under shifting cultivation (JH1), low quality (SQIw < 0.50), only to FS3, and intermediate quality (0.50 < SQI < 0.70) in all other soils. The approach used in this study proved to be sensitive to evaluate the soil quality, however further research is required to better understand the sustainability of shifting cultivation by including more physical, biological and chemical indicators.     

Soil quality indices for evaluation of long‐term land use and soil management practices in semi‐arid sub‐tropical India

Land use changes and soil management can potentially alter soil quality. A study was conducted to assess the long‐term (>20 years) effects of perennial trees (PT), vegetable crops (VC), rice–wheat (RW) system, sewage‐irrigated fields (SF), maize–wheat (MW) system and uncultivated soils (US) on soil quality. Soil physical quality parameters were significantly affected only in the SF system when compared with the US soil, particularly for bulk density (BD 1·51 Mg m⁻³ in SF vs. 1·34 in US). Among chemical parameters, electrical conductivity was high in SF, and soil nutrients (N, P, K, S, Zn, Fe, Cu and Mn) were well above the critical limits of deficiency in all the systems. Soil parameters were integrated into soil quality indices (SQIs) by unscreened transformation and principal component analysis (PCA). SQI observed under each system were compared with the US to assess the degree of degradation. Mean SQI differences showed that PT (+16·02 per cent), VC (+4·80 per cent), RW (+10·04 per cent), and MW (+11·30 per cent) are aggrading, whereas SF (−2·06 per cent) is degrading with respect to the reference soil (US). Adoption of MW system proved to be better than traditional RW; and in general agricultural crops have a significant advantage than VC, in terms of maintaining soil quality. Sewage irrigation is not a sustainable practice and long‐term use may degrade the soil. Among the SQIs, PCA with nonlinear scoring function (NLSF) based SQI was effective in judging land degradation due to soil quality changes as affected by long‐term land use and soil management practices. Copyright © 2008 John Wiley & Sons, Ltd.     

北京山区不同植被恢复类型土壤质量综合评价

[目的] 综合评价北京山区不同植被恢复类型土壤质量,并进一步确定影响土壤质量的关键因素,为该地区植被恢复与重建提供数据支撑。[方法] 以立地条件相近的侧柏纯林、油松纯林、侧柏油松混交林、侧柏针阔混交林、油松针阔混交林、落叶阔叶混交林和无林地(对照)为研究对象,测定14个土壤理化指标作为土壤质量评价的总数据集(TDS),采用主成分分析法(PCA)和Pearson相关性分析建立土壤质量最小数据集(MDS),利用线性(L)和非线性(NL)2种评分方法计算土壤质量指数(SQI)和一般线性模型(GLM)确定影响土壤质量的关键因素。[结果] 植被恢复后相较于无林地,土壤容重、砂粒含量下降,而有机质、全氮、全钾、速效氮、速效钾等土壤养分含量增加。筛选出的研究区土壤质量评价MDS指标为全氮、砂粒、全钾、pH、有效含水量。4种方法(SQI-LT、SQI-NLT、SQI-LM、SQI-NLM)下,不同植被恢复类型的SQI值排序均为落叶阔叶混交林＞侧柏针阔混交林＞油松纯林＞油松针阔混交林＞侧柏油松混交林＞侧柏纯林＞无林地,植被恢复后土壤质量显著提升。SQI-NLM的土壤质量评价方法在北京山区具有更好的适用性。相较于无林地,其他植被恢复类型的SQI-NLM分别提高64%,48%,45%,36%,33%,27%。GLM模型解释了土壤质量指数总变异的85.24%,植被类型对土壤质量指数的解释比例最大(45.09%)。[结论] 选择适宜的植被恢复类型是改善区域土壤质量的关键。未来实施植被恢复时,树种选择上优先考虑阔叶树种。造林配置方式的选择应取决于树种而定,如侧柏纯林中引入本土阔叶树种形成侧柏针阔混交林或选择油松纯林是最佳造林模式。     

中国东北农田土壤质量评价的最小数据集选择

Soil quality assessment provides a tool for agriculture managers and policy makers to gain a better understanding of how various agricultural systems afect soil resources.Soil quality of Hailun County,a typical soybean (Glycine max L.Merill) growing area located in Northeast China,was evaluated using soil quality index(SQI)methods.Each SQI was computed using a minimum data set(MDS) selected using principal components analysis(PCA)as a data reduction technique.Eight MDS indicators were selected from 20 physical and chemical soil measurements.The MDS accounted for 74.9% of the total variance in the total data set(TDS).The SQI values for 88 soil samples were evaluated with linear scoring techniques and various weight methods.The results showed that SQI values correlated well with soybean yield (r=0.658**) when indicators in MDS were weighted by the regression coefcient computed for each yield and index.Stepwise regression between yield and principal components (PCs) indicated that available boron(AvB),available phosphorus (AvP),available potassium (AvK),available iron (AvFe) and texture were the main factors limiting soybean yield.The method used to select an MDS could not only appropriately assess soil quality but also be used as a powerful tool for soil nutrient diagnosis at the regional level.     

生物炭施用对麦田土壤团聚体机械稳定性及春小麦产量的影响

  目的  研究生物炭添加对灌区麦田土壤团聚体分布、稳定性及作物产量的影响,阐明土壤及作物对生物炭培肥效果的响应,为灌区麦田土壤结构改良和合理培肥制度建立提供理论依据。  方法  试验采用裂区设计,氮肥（纯氮）用量设0、150 kg hm?2两个水平,每一氮肥用量下设生物炭用量0,10,20,30 t hm?2 4个水平,通过2年（2018 ~ 2020年）田间定位试验,利用干筛法得到了不同粒级土壤团聚体含量,对土壤团聚体稳定性指标和春小麦产量进行对比分析。  结果  与不添加生物炭相比,添加生物炭显著提高了 > 5 mm、2 ~ 5 mm粒级土壤团聚体含量（P < 0.05）,增幅范围为10.2% ~ 29.2%、8.3% ~ 10.2%;施用生物炭20 t hm?2时土壤团聚体平均重量直径及几何重量直径增幅最为显著(P < 0.05),较不施生物炭处理相比分别增加了21.4%和32.3%;生物炭配施氮肥春小麦增产效果优于单施生物炭处理;土壤团聚体几何重量直径与春小麦产量之间呈显著的正相关关系。  结论  生物炭施用对灌区麦田土壤大团聚体形成及其稳定性提升效果显著,有利于改良土壤,提升春小麦产量。在本试验条件下,单施生物炭20 t hm?2时土壤团聚体稳定性最强,生物炭20 t hm?2与纯氮150 kg hm?2配施时产量最高,与对照相比春小麦增产达42.7%。     

Mapping Land Suitability for Agriculture in Malawi

Population growth, climate sensitivity, and edaphic properties are important factors that influence decision‐making and risk mitigation for agricultural production. Within the agricultural sector in Malawi, continuous cropping without the use of long‐term sustainable strategies and frequent cultivation on marginal lands have resulted in continually declining soil fertility. Improving soil quality of marginal lands using innovative technologies is imperative for increasing agricultural productivity and improving food security. Here, we propose an ensemble approach to map agricultural land suitability and identify the distribution of marginal land in Malawi. Quantitative data available for eight soil and terrain factors were rated individually, and five distinct models were applied to generate a spatial distribution map of land suitability. The results indicate that highly suitable, moderately suitable, marginally suitable, and unsuitable agricultural areas account for 8·2%, 24·1%, 28·0%, and 39·7% of the total land area, respectively. The majority of suitable lands are currently used for agriculture, but more than half (57·4%) of Malawi's total cropland exists on marginally suitable or unsuitable land categories and is likely a candidate for rehabilitation through sustainable agricultural practices. The methods and products herein will be valuable resources for effectively managing and improving Malawi's agricultural lands for increasing food security. Copyright © 2017 John Wiley & Sons, Ltd.     

Development of a land suitability model for saffron (Crocus sativus L.) cultivation in Khost Province of Afghanistan using GIS and AHP techniques

In this study, we have attempted to develop a land suitability model for saffron, an agronomic crop, which is economically viable, environmentally bearable and socially equitable at Khost Province of Afghanistan. The objective was to determine different land suitability classes for saffron cultivation using Analytical Hierarchy Process (AHP) and Geographic Information System (GIS). A decision tree was developed encompassing the physical, economic and social criteria. We used the secondary data (meteorological, remote sensing) from available sources and also substantial primary data generated from soil survey, interviews and experts’ opinion. A total of 30 physical and socio-economic factors were included in the analysis. The final land suitability result showed that out of the total land area of Khost Province, 1.5, 4.5, 8.6 and 85.4% areas were highly suitable, moderately suitable, marginally suitable and not suitable, respectively. This modelling approach can be applied to determine the suitability of land for other crops covering a wider geographical region of Afghanistan.     

湖北省坡耕地现状分析及宜耕性评价

坡耕地是耕地资源的重要组成部分,也是土壤侵蚀的策源地和水土保持的重点区域。为探究湖北省坡耕地资源现状及其宜耕性,利用GIS技术,构建了湖北省坡耕地的坡度、土壤侵蚀、土壤剖面构型和理化特性等数据库,筛选耕地坡度、土层厚度、土壤质地、土壤pH值和土壤侵蚀程度5个代表性指标,采用“限制因子法”对湖北省全域坡耕地进行了宜耕性评价。结果表明：湖北省坡耕地总面积为9 438.64 km²,占总耕地面积的18.87%,不宜耕坡耕地总面积为2 178.36 km²,占现有坡耕地面积的23.08%;砾石含量和坡度过高是造成坡耕地不宜耕的主要因素,其中砾石含量>15%的坡耕地总面积为1 205.72 km²,坡度≥25°的坡耕地总面积为1 097.32 km²;其次不宜耕主导因素是土壤过酸,pH值≤4.5造成坡耕地不宜耕的面积为669.60 km²,土壤侵蚀严重(极强烈以上侵蚀强度)和土层浅薄(土层厚度<30 cm)造成的不宜耕坡耕地面积分别为336.48 km²...     

Application of the soil-ecological multiplicative index to assess suitability of Cis-Ural chernozems for cultivation with due account for economic parameters

The evolution of Russian concepts concerning the assessment of soil suitability for cultivation in relation to several campaigns on large-scale plowing of virgin steppe soils is examined. The major problems of agricultural land use in steppe areas—preservation of rainfed farming in the regions with increasing climatic risks, underestimation of the potential of arable lands in land cadaster assessments, and much lower factual yields in comparison with potential yields—are considered. It is suggested that the assessments of arable lands should be performed on the basis of the soil–ecological index (SEI) developed by I. Karmanov with further conversion of SEI values into nominal monetary values. Under conditions of land reforms and economic reforms, it is important to determine suitability of steppe chernozems for plowing and economic feasibility of their use for crop growing in dependence on macroeconomic parameters. This should support decisions on optimization of land use in the steppe zone on the basis of the principles suggested by V. Dokuchaev. The developed approach for assessing soil suitability for cultivation was tested in the subzone of herbaceous–fescue–feather grass steppes in the Cis-Ural part of Orenburg oblast and used for the assessment of soil suitability for cultivation in the southern and southeastern regions of Orenburg oblast.     

"藏粮于地"视角下西北地区耕地适宜性及开发潜力评价

中国耕地资源匮乏,人均耕地不足世界平均水平的40%。西北"水三线"地区是中国耕地后备资源的关键区域,识别潜在耕地资源中适宜开发的土地数量及空间分布,对确保极端情况下国家耕地红线和粮食安全、推动西部大开发进入新格局具有重大现实意义。基于多源栅格数据,采用综合指数法与极限条件法评价潜在耕地资源的自然适宜性潜力;同时考虑土地利用结构风险、土壤侵蚀风险、土地荒漠化风险限制,构建潜在耕地开发的生态风险模型;将自然适宜性潜力和生态风险评价结果进行叠置分级,评估潜在耕地资源的综合开发潜力。结果表明:旱地农业情景下,西北"水三线"地区具备耕地开发潜力的土地面积约0.2万km~2,主要分布在内蒙古半干旱草原区;灌溉农业情景下,西北"水三线"地区具备耕地开发潜力的土地面积约9.5×10~4 km~2,这些土地需要通过引水灌溉和土壤改良等措施才能实现粮食生产,主要集中在天山北麓、塔里木河流域、疏勒河流域和内蒙古东部等内陆干旱区,未来如果具备灌溉水源条件,实施适宜的土壤改良措施,有较大可开发潜力。     

Large‐scale soil maps and a supplementary database for land use planning in Estonia

A soil map at the scale 1:10,000 serves as a major important document for land owners and local governments, which allows them to use soil information in their daily activity. The intensity of exploitation of soil maps will increase when the very map and its legend are supplemented, within colored and indexed polygons, with information about soil texture and reaction by layers, but also about the thickness and characterization of the epipedon, quality indices for soil assessment, classes of stoniness, and prevalent fractions of stones, erosion risk, etc. Special maps of agronomical status, with a list of proper measures for improvement of soils and their associations, should form a regular component of large‐scale mapping. As decrease in arable land and increase in the forest area are common trends in land use, these maps and general soil data should serve as the fundamental source of information for decision making concerning land use. Data indicating the suitability of any soil for any crop should be entered in a database. Application of GIS on any level of national economy, digitization of a large‐scale soil database and making it accessible to land users would allow to expand the amount of available information for each soil map polygon.     

Comparison of methods for evaluating the suitability of Vertisols for Gossypium hirsutum (Bt cotton) in two contrasting agro-ecological regions

Cotton (Gossypium sp.) is a major crop grown under rainfed conditions in Vertisols and associated soils in semi-arid tropical (SAT) regions of Peninsular India. In recent years, cotton productivity has declined due to various biophysical factors including pest and diseases, seasonal water stress soil degradation and poor crop management practices. In this study, we compare two methods for evaluating the suitability of Vertisols for cotton in contrasting two agro-ecological regions viz., sub-humid moist (SHM) region and semi-arid dry(SAD) were characterized. Twelve cotton growing Vertisols (seven from SHM and five from SAD) were evaluated for their suitability for cotton cultivation using soil quality index (SQI) and modified Sys-FAO method. SQIs were calculated using the weighted additive index from transformed scores of selected indicators by principal component analysis. For Sys-FAO method both biophysical and soil characteristics were considered for suitability evaluation. We found that the soils of SHM region were moderately suitable for cotton cultivation with soil moisture as the major limiting factor, whereas the soils of SAD region are marginally suitable due to high exchangeable sodium percentage and poor hydraulic conductivity. From this, it may be concluded that the weighted SQI has better agreement with the cotton yield.     

基于最小数据集的黄土高原矿区复垦土壤质量评价

矿产开发影响了土壤质量,特别是在黄土高原生态脆弱地区。通过植被恢复能够改善矿区复垦土壤质量。为了揭示矿区复垦土壤质量在植被恢复过程中的变化,该文以黑岱沟矿区排土场不同恢复年限不同植被类型、未复垦地和周边自然植被恢复区为研究对象,选取21项理化生指标作为总数据集(totaldataset,TDS),运用主成分分析(principal component analysis,PCA)结合Norm值构建评价指标最小数据集(minimum data set,MDS),通过非线性(non-Linear,NL)和线性(linear,L)两种评价方法对研究区土壤质量进行了评价。研究表明:黄土高原北部典型矿区复垦土壤质量评价指标MDS包括粉粒百分比、有机质、速效磷、钠吸附比和微生物碳;2种评价方法下,植被恢复均对复垦土壤质量指数(soil quality index,SQI)有了显著提升(P 0.05),复垦20 a灌木SQI高于复垦10 a灌木SQI,复垦12 a草本SQI高于复垦20 a草本SQI,然而所有复垦土壤SQI均未达到自然植被恢复土壤SQI;由于非线性土壤质量评价方法(SQI-NL)具有更大的土壤质量指数变化区间和变异系数,此外,在SQI-NL和线性土壤质量(SQI-L)评价两种方法下,MDS和TDS之间决定系数分别为0.911和0.866,因此,非线性土壤质量评价方法在该区域具有更好的适用性,并且最小数据集能够较准确地进行土壤质量评价。