Assessment of the FAO traditional land evaluation methods,A case study: Iranian Land Classification method

Land evaluation is a critical step in land‐use planning. Although many methods have been developed since the formulation of the FAO framework for land evaluation, several of the more traditional approaches still remain in widespread use but have not been adequately evaluated. Contrary to more recent land evaluation systems, which need considerable data, these systems only require basic soil and landscape information to provide a general view of land suitability for major types of land use. As the FAO initially presented its qualitative framework for land‐use planning, based on two previous methods developed in Iran and Brazil, in this study we assessed the reliability and accuracy of a traditional land evaluation method used in Iran, called land classification for irrigation (LCI), comparing its results with several qualitative and quantitative methods and actual yield values. The results showed that, although simpler than more recently developed methods, LCI provided reliable land suitability classes and also showed good relationships both with other methods analysed and with actual yields. Comparisons between qualitative and quantitative methods produced similar results for common crops (a barley–alfalfa–wheat–fallow rotation). However, these methods performed differently for opportunist crops (such as alfalfa) that are more dependent on income and market conditions than on land characteristics. In this work, we also suggest that using the FAO method to indicate LCI subclasses could help users or managers to recognize limitations for land‐use planning.     

河南嵩县土地整理的数量质量潜力

该文在综合分析前人土地整理潜力理论研究基础上,结合农用地分等成果,在原有耕地整理数量潜力基础上,引入了耕地整理质量潜力,并系统制定了耕地整理数量潜力和质量潜力评价理论及方法;同时,也进行了耕地整理质量潜力测算方法的探讨和实证研究,计算出嵩县耕地整理质量提高潜力,分别计算了耕地整理的自然质量提高潜力和耕地整理的利用提高潜力,划分了不同的质最提高潜力区,通过计算,全县可以新增粮食总产量为7.15万t,平均每公顷提高潜力为1561.8kg.最终把耕地整理数量潜力成果与质量潜力成果相结合,划分出县域耕地整理的综合潜力级别区域.     

Screening of Tanzanian sweet potato germplasm for yield and related traits and resistance to sweet potato virus disease

Sweet potato (Ipomoea batatas [L.] Lam) is a versatile crop globally serving as food, feed and raw material for industries. Designed selection for higher yields and related traits is crucial to identify complementary sweet potato clones for breeding. The objective of this study was to determine phenotypic variation among diverse sweet potato collections with regard to yield, dry matter content (DMC) and sweet potato virus disease (SPVD) resistance and to identify suitable clones for breeding. A total of 144 sweet potato genotypes were evaluated at 2 sites in Tanzania using a 12?×?12 simple lattice design. Data collected included 10 quantitative and 17 qualitative agro-morphological traits and virus reaction. Results indicated differences among genotypes for most traits studied. The mean DMC was 36% with clones Zapallo and Ukerewe exhibiting the lowest and highest values of 29% and 45%, respectively. The mean storage root yield of clones was 5.1?t/ha with genotype Jewel expressing the highest yield of 11.3?t/ha. Genotypes Resisto and Mataya were early flowering at 40 and 50 days, respectively, while Ex-Mwanza and Kandoro did not flower at all. Fifty-eight per cent of the genotypes showed resistant reaction to SPVD, while 31% and 11% were moderately susceptible and susceptible to the disease, respectively. A positive correlation was observed for the number of roots and fresh root yield. Seven clones including Simama, Ukerewe, Mataya, Resisto, 03–03, Ex-Msimbi-1 and Gairo were selected for high storage root yield and related traits or SPVD resistance. The selected genotypes are recommended as potential parents for sweet potato breeding.     

Spatial interpolation of soil hydraulic properties and simulated rice yield

Abstract. Simulated estimates of crop yield were made for rainfed rice in a 50 ha dryland rice area. The aim was to investigate how soil units and management units of different sizes with different yields could be used to obtain values for areas of land. Two procedures were applied. First, yields were simulated at six sites, that were representative of six soil mapping units. Second, yields were simulated using soil information from 133 auger sites, and were interpolated over management units using block kriging. Differences between the two procedures for the total area and for a test set of 22 additionally sampled locations were small. A 60% increase in precision was achieved when relatively large management units were defined.
A Geographical Information System was used to identify areas with greatest yield potential for rainfed dryland rice. Statistical analysis showed that the six soil units could be grouped into three yield classes. The largest yields were obtained for a sub-area comprising 11% of the survey area which was associated with a slowly permeable Bg horizon in the soil profile.
It was concluded that the best procedure for the spatial interpolation of simulated rice yield should be based on preliminary simulation of crop yields. A sensitivity analysis of the impact of weather variability and soil heterogeneity on the variation of yield was useful to detect the importance of their contributions. The procedures developed in this study are of value in obtaining a reliable estimate of average yield, and can consequently be used for associated cost-benefit calculations.     

Use of GIS to Delineate Site-Specific Management Zone for Precision Agriculture

Soil heterogeneity is one of the several factors that explain within-field variations in crop yielding. To overcome this problem, an experiment was conducted within the University of Ibadan to identify the zones with similar soil properties that can be managed uniformly to optimize crop yield. A total of 62 soil samples were collected from 6.5 ha of farmland based on the differences in slope, soil moisture regime, land management and cropping pattern. The spatial distributions of soil properties were mapped out using the Inverse Distance Weighing (IDW) interpolation technique and the results were subsequently reclassified into different soil management categories. The results showed that the farmland consists of four classes of total nitrogen (N), phosphorus (P) and soil bulk density (SBD); three classes of carbon (C) and volumetric moisture content (?); two classes of soil _pH; and one class of soil texture. Each of the soil management maps was subsequently overlaid on each other to produce four specific site management units (SSMUs) for vegetable cultivation. The four SSMUs consisted of highly suitable units occupying 0.143 ha, marginally suitable unit occupying 0.971 ha, moderately suitable unit occupying 0.517 ha and unsuitable unit occupying 4.9 ha of land. The SSMUs will alleviate problems of reduced yield due to over- or under-applications of agrochemicals.     

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.     

Qualitative and quantitative land-suitability evaluation for sunflower and maize in the north-west of Iran

Land evaluation is the act of predicting the use potential of land on the basis of its attributes. The objective of this study was to evaluate qualitative and quantitative land suitability for the north-west of Iran on the basis of a FAO model for sunflower and maize crops. Growing cycle was determined using the CDBm (Monthly Climate Database) model and soils were classified in two orders of Mollisols and Vertisols, which consisted of seven soil families based on soil data and Keys to Soil Taxonomy 2010. Qualitative evaluation was carried out using the square root of parametric (SRP) method and quantitative evaluation was performed on the basis of observed yields under an average management level. The results showed that in the surveyed area, the climatic class had moderate suitability (S2) for maize and sunflower due to limitations imposed by the relative humidity of the growing cycle. The most important land limitation factors were soil parameters like pH, CaCO₃ content, texture and coarse fragments, as well as topography and drainage in the area of study. Based on qualitative evaluation with SRP, 24.69 and 17.71% of land had non-suitable class (N1) for maize and sunflower, respectively. Quantitative land suitability for maize and sunflower showed that 24.69 and 9.81% of land had non-suitable class (N1), respectively.     

中国海南岛香蕉种植潜力的鉴定

Land use alternatives are sought to boost agricultural income and productivity in Hainan Island,China.Regional differences exist in crop limitations,such as typhoon risk,low temperatures,poor soil fertility,and drought.In this study a crop zonation was made for a range of crops,among which is banana,as a way to:1) establish areas for potential expansion for banana,and 2) identifylimitations and options for crop and land management.A spatial soil and terrain database of Hainan Island(1:250000) was linked to the automated land evaluation system(ALES).The qualitative models were verified by comparing suitability maps with actual land use.Theresults may support policy formulation on issues such as alternatives to current land use,assessment of best management practices,and the need for fertilizer programmes.     

Integration of biophysical and economic data using an expert system: results from a case study in northern Australia

Abstract. Biophysical and economic data from numerous sources are integrated using the ALES expert system. A systematic approach to data collection and evaluation procedure is presented. The collection of management data is emphasized if management and crop yield data are to be adequately correlated. Different land utilization types are evaluated for numerous land mapping units. The results show that direct comparison of land mapping units is possible both within and between different land utilization types. Use of the model enabled objective relationships to be developed between biophysical criteria, crop productivity and management, allowing economic measures of performance to be routinely determined for large databases. The study shows that land mapping units with the most favourable physical suitability class may not necessarily have the largest net return and that the best lands are determined not only by their ability to produce high yields but also their ability to achieve them at the least cost.     

MicroLEIS: A microcomputer-based Mediterranean land evaluation information system

Abstract. A computer-based land evaluation information system (MicroLEIS) was developed for optimal use of agricultural and forestry land systems under Mediterranean conditions. Through an interactive procedure several land capability, suitability and yield prediction methods may be applied. The system addresses land evaluation at reconnaissance, semi-detailed and detailed scales in an interrelated manner. Biophysical land evaluation methods are incorporated using empirical, scale-appropriate models, which range from purely qualitative (reconnaissance) through semi-quantitative (semi-detailed) to quantitative (detailed). This software is helpful for teaching, research and development, predicting appropriate agroforestry land uses. Its use is illustrated by an example.
MicroLEIS runs on IBM PC, XT, AT, or a compatible microcomputer with at least 128 kilobytes of RAM and a PC-DOS or MS-DOS version 2.0 or later operating system. The software package on double or high density diskettes can be obtained from the first author.     

海涂土地资源适宜性空间分析与优化开发模式研究

海涂是沿海地区重要的后备土地资源,适宜性评价与优化利用结构是科学开发海涂的前提.选取典型海涂围垦区,把GIS空间分析与数学规划模型结合起来,首先基于GIS空间分析技术,对海涂土地资源适宜性进行评价;然后针对研究区内的新围海涂,运用数学规划模型对其土地利用数量结构进行优化,优化结果中总土地开发利用系数为0.629,在开发投资效益最大化的基础上兼顾了海涂生态环境保护.结合海涂开发用地规划,提出土地利用结构的优化配置模式,实现海涂土地资源开发中定性分析、定位配置与定量优化的结合.     

Soil loss tolerance in the central chernozemic region of the European part of Russia

To calculate the soil loss tolerance for chernozems of the central chernozemic region, a linear modification of Skidmore’s equation was used. The soil loss tolerance values were obtained with due account for the soil type, the degree of erodibility, and the crop rotation pattern. The maximum possible value (10 t/ha per year) was obtained for a typical noneroded chernozem in all the crop rotations. Close values were obtained for noneroded leached and typical chernozems (9.6–9.9 t/ha per year depending on the crop rotation pattern). The soil loss tolerance for the noneroded podzolized chernozem was somewhat lower: 9.1 t/ha per year in the grain-herb-intertilled crop rotation and 6.3 t/ha/year in the grain-intertilled crop rotation. With an increase in the degree of the soil erosion, the soil loss tolerance decreased in all the variants of the experiment with an especially abrupt decrease in the grain-intertilled crop rotation (from 9.9–10.0 to 0.3–2.0 t/ha per year in the, respectively, noneroded and slightly eroded ordinary and typical chernozems). In the grain-herb-intertilled crop rotation, these differences were much smaller: in the slightly eroded typical chernozem the soil loss tolerance was estimated at 9.7 t/ha per year, while, in the slightly eroded typical chernozem, at 8.1 t/ha per year. The moderately eroded chernozems without the addition of manure could only be used in the grain-herb-intertilled crop rotation; the soil loss tolerance was estimated at 9.0 t/ha per year for the typical chernozem and 4.3 t/ha per year for the ordinary chernozem.     

基于生态安全的黄河三角洲未利用地开垦潜力评价

未利用地的开垦是土地开发人们关注的重要议题,其中评价指标体系的构建是重要的研究方向。该文深入分析影响研究区土地开发利用的各种因素,从生态安全性、自然适宜性、经济可行性3个方面构建未利用地宜耕性评价指标体系。以土地利用空间数据库为基础,利用GIS空间分析功能对各评价要素空间图层进行叠加和统计分析,研究未利用地在不同条件下适宜性开发的面积和空间分布格局。研究表明,东营市未利用地总规模为27.14万hm2,考虑生态因素后,可开垦的未利用地面积为7.72万hm2,所占比例为28.44%。从自然适宜性评价来看,可开垦利用的未利用地面略有减少,面积为7.49万 hm2。考虑经济因素之后,可开发利用的未利用地为3.67万hm2,所占比例为13.72%。研究结论,生态因素和经济因素是制约东营市未利用地开垦的主要因素,可开发利用的未利用地为3.67万hm2。该研究结果可为东营市未利用地开发整理规划提供参考。     

Using expert systems and simulation modelling for land evaluation at farm level: a case study from New York State

Abstract. A land evaluation at farm level was made for a toposequence of three New York soils, using the FAO framework and the LEACHN simulation model. The land utilization type (LUT) was continuous corn, using three varieties with different growing periods. Ten experts identified the same land qualities but three different types of land characteristics, as derived from soil survey data, field observations and simulation modelling. Differences could be explained by the backgrounds of the experts. A land evaluation procedure according to framework criteria using decision trees rather than matching tables was more accessible and transparent. Simulation of the soil-water regime provided quantitative data for all land qualities considered, and this procedure was preferred to qualitative estimates based on poorly defined procedures. When some land qualities cannot be characterized by simulation, however, a mix of qualitative and quantitative decision tree branches may be considered. The standard scheme of land evaluation, which is scale independent, provides irrelevant results at farm level because farmers' questions are different from those of regional planners who are well served by the traditional land evaluation procedure. For the farmer, development of decision support systems should be focused on optimal management decisions.     

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.     

基于耕地系数和预评价法的耕地整治潜力测算方法

为科学合理测算耕地整治潜力,提高潜力测算结果的应用性,该文结合二调数据及农用地分等数据,进行了耕地整治数量潜力和质量潜力的测算研究,耕地整治数量潜力测算采用耕地系数法(CLC,cultivated land coefficient),耕地整治质量潜力测算采用农用地分等因子提高后的预评价法。研究表明:五华县耕地整治潜力较大,数量总潜力为841.69 hm2,各行政村数量潜力分布情况为南高北低;质量潜力方面,经过整治,耕地自然等别可平均提高1.28等,利用等别可平均提高0.71等,生产能力可提高57 862.99×104kg。该研究方法符合当地土地整治实际情况,研究结果可为制定县域土地整治规划、划定高标准基本农田建设区及确定耕地整治建设重点项目区提供参考。     

Development of a simulation based land evaluation system using crop modelling, expert systems and risk analysis

Abstract. Current methods of agricultural land evaluation in Queensland and other parts of Australia have been criticized for their inflexibility and lack of attention to costs (both private and social) associated with particular land uses. These deficiencies can limit the usefulness of land evaluation procedures in defining land capability and suitability for farm and regional land use planning. This paper outlines a new method based on soil potential ratings, that incorporates biophysical crop simulation modelling, expert systems and risk analysis. The technique is able to integrate biophysical and economic data in a measure which can be readily computed, updated and communicated to land managers.     

低洼易涝盐碱地中影响旱稻产量的因素分析--以河北省南皮县"七万亩"试区为例

本文以河北省南皮县“七万亩”试区为例，采用方差和通径分析的方法，对旱稻产量变化在0.36吨每公顷--6.5吨每公顷条件下低洼易涝盐碱地中影响旱稻产量的因素进行了分析。结果表明，在这样的条件下，首先应注意保苗及全苗技术，从而保证收获时的单位面积上的穗数，这是获高产的第一因子，其次是提高千粒重的栽培措施，再者是提高每穗粒数的方法。大穗品种不宜在类似条件下推广，而早熟品种则需要引起足够的重视。     

Evaluating the land use potential of gypsiferous soils from field pedogenic characteristics

Abstract. Although gypsiferous soils cover approximately 100 million ha in the world, it is only in the past two decades that their pedogenic and agronomic properties have been better understood and their classification improved. There is still no method to assess adequately their production potential.
This paper focuses on gypsum accumulation forms as diagnostic criteria for a rapid soil suitability appraisal in the field. Pseudomycelia, gypsum spots, powdery coatings and other localized in situ precipitations usually indicate soils with less than 15% gypsum. Depending on their intensity and depth of occurrence in the root zone, they define a soil environment which is suitable for semi-sensitive and semi-tolerant crops. Continuous gypsum accumulations characterize soils or horizons with high (e.g. more than 25%) gypsum contents, and these can be used only for tolerant crops.
The land use potential of gypsiferous soils is primarily determined by: (a) the depth of the impermeable layer, (b)the gypsum content within the root zone, and (c) the crop tolerance level. A method is proposed to assess the land suitability of gypsiferous soils on the basis of these criteria.