Conventional soil maps generally contain one or more soil types within a single soil polygon.But their geographic locations within the polygon are not specified.This restricts current applications of the maps in site-...Conventional soil maps generally contain one or more soil types within a single soil polygon.But their geographic locations within the polygon are not specified.This restricts current applications of the maps in site-specific agricultural management and environmental modelling.We examined the utility of legacy pedon data for disaggregating soil polygons and the effectiveness of similarity-based prediction for making use of the under-or over-sampled legacy pedon data for the disaggregation.The method consisted of three steps.First,environmental similarities between the pedon sites and each location were computed based on soil formative environmental factors.Second,according to soil types of the pedon sites,the similarities were aggregated to derive similarity distribution for each soil type.Third,a hardening process was performed on the maps to allocate candidate soil types within the polygons.The study was conducted at the soil subgroup level in a semi-arid area situated in Manitoba,Canada.Based on 186 independent pedon sites,the evaluation of the disaggregated map of soil subgroups showed an overall accuracy of 67% and a Kappa statistic of 0.62.The map represented a better spatial pattern of soil subgroups in both detail and accuracy compared to a dominant soil subgroup map,which was commonly used in practice.Incorrect predictions mainly occurred in the agricultural plain area and the soil subgroups that are very similar in taxonomy,indicating that new environmental covariates need to be developed.We concluded that the combination of legacy pedon data with similarity-based prediction is an effective solution for soil polygon disaggregation.展开更多
Placic horizons, defined as thin, wavy, hardened layers of iron and organic matter, are rare within the United States, occurring only in Washington, Alaska, and Hawaii. While ironstone is common in many soils of the s...Placic horizons, defined as thin, wavy, hardened layers of iron and organic matter, are rare within the United States, occurring only in Washington, Alaska, and Hawaii. While ironstone is common in many soils of the southeastern United States, it is not known to contain appreciable organic matter. As a pilot study evaluating the justification for a larger study on ironstone in Louisiana, a 40 m lateral exposure with suspected placic horizons was evaluated in Vernon Parish, Louisiana. Results of laboratory analysis show elevated levels of iron and organic matter in the suspect horizons that meet the criteria of placic horizons as defined by the Soil Survey Staff. Based on the results of this study, additional evaluation of multiple pedons with similar features is warranted. Should additional pedons demonstrate similar properties, a new great group of 'Petrudepts' would be needed to describe both the placic horizons in the pedon and the udic moisture regime in which they occur.展开更多
The purity of soil map units and their quality for various uses like land suitability evaluation are always questioned.The main objective of this study was to compare the precision of qualitative land suitability clas...The purity of soil map units and their quality for various uses like land suitability evaluation are always questioned.The main objective of this study was to compare the precision of qualitative land suitability classification based on geostatistical and conventional soil mapping methods for main irrigated crops in the Shahrekord Plain,Central Iran.A regular grid sampling method consisting 104sample points was designed and soil samples were collected.Ordinary kriged maps were achieved for all studied soil attributes after physico-chemical analyses.Afterward,to combine kriged maps and ecological requirements of the studied crops,a script was designed in ILWIS 3.4 software and consequently,kriged qualitative land suitability maps were generated.Conventional qualitative land suitability was also mapped based on the representative pedon analysis in each soil map unit.Finally,comparison of the conventional and kriged maps was carried out using the statistical method,error matrix.The results showed that the overall accuracies of wheat,sugar beet,potato and alfalfa maps were 39.8%,24.3%,18.7%and 18.6%at subclass category,respectively,whereas these values increased to80.9%,82.3%,23.7%and 82.3%at class level,respectively.Hence,it can be stated that thanks to the relative facility of conventional soil survey compared with geostatistical methods,this method can be expressed as a preferable way for handling a usual land suitability evaluation design;but using soil map units as land suitability delineations may lead to unsatisfactory results in estimation of quantity and type of existing limitations.展开更多
基金supported by the National Natural Science Foundation of China (41130530,91325301,41431177,41571212,41401237)the Project of "One-Three-Five" Strategic Planning & Frontier Sciences of the Institute of Soil Science,Chinese Academy of Sciences (ISSASIP1622)+1 种基金the Government Interest Related Program between Canadian Space Agency and Agriculture and Agri-Food,Canada (13MOA01002)the Natural Science Research Program of Jiangsu Province (14KJA170001)
文摘Conventional soil maps generally contain one or more soil types within a single soil polygon.But their geographic locations within the polygon are not specified.This restricts current applications of the maps in site-specific agricultural management and environmental modelling.We examined the utility of legacy pedon data for disaggregating soil polygons and the effectiveness of similarity-based prediction for making use of the under-or over-sampled legacy pedon data for the disaggregation.The method consisted of three steps.First,environmental similarities between the pedon sites and each location were computed based on soil formative environmental factors.Second,according to soil types of the pedon sites,the similarities were aggregated to derive similarity distribution for each soil type.Third,a hardening process was performed on the maps to allocate candidate soil types within the polygons.The study was conducted at the soil subgroup level in a semi-arid area situated in Manitoba,Canada.Based on 186 independent pedon sites,the evaluation of the disaggregated map of soil subgroups showed an overall accuracy of 67% and a Kappa statistic of 0.62.The map represented a better spatial pattern of soil subgroups in both detail and accuracy compared to a dominant soil subgroup map,which was commonly used in practice.Incorrect predictions mainly occurred in the agricultural plain area and the soil subgroups that are very similar in taxonomy,indicating that new environmental covariates need to be developed.We concluded that the combination of legacy pedon data with similarity-based prediction is an effective solution for soil polygon disaggregation.
文摘Placic horizons, defined as thin, wavy, hardened layers of iron and organic matter, are rare within the United States, occurring only in Washington, Alaska, and Hawaii. While ironstone is common in many soils of the southeastern United States, it is not known to contain appreciable organic matter. As a pilot study evaluating the justification for a larger study on ironstone in Louisiana, a 40 m lateral exposure with suspected placic horizons was evaluated in Vernon Parish, Louisiana. Results of laboratory analysis show elevated levels of iron and organic matter in the suspect horizons that meet the criteria of placic horizons as defined by the Soil Survey Staff. Based on the results of this study, additional evaluation of multiple pedons with similar features is warranted. Should additional pedons demonstrate similar properties, a new great group of 'Petrudepts' would be needed to describe both the placic horizons in the pedon and the udic moisture regime in which they occur.
基金Supported by the Vali-e-Asr University of Rafsanjan,Iran(No.518)
文摘The purity of soil map units and their quality for various uses like land suitability evaluation are always questioned.The main objective of this study was to compare the precision of qualitative land suitability classification based on geostatistical and conventional soil mapping methods for main irrigated crops in the Shahrekord Plain,Central Iran.A regular grid sampling method consisting 104sample points was designed and soil samples were collected.Ordinary kriged maps were achieved for all studied soil attributes after physico-chemical analyses.Afterward,to combine kriged maps and ecological requirements of the studied crops,a script was designed in ILWIS 3.4 software and consequently,kriged qualitative land suitability maps were generated.Conventional qualitative land suitability was also mapped based on the representative pedon analysis in each soil map unit.Finally,comparison of the conventional and kriged maps was carried out using the statistical method,error matrix.The results showed that the overall accuracies of wheat,sugar beet,potato and alfalfa maps were 39.8%,24.3%,18.7%and 18.6%at subclass category,respectively,whereas these values increased to80.9%,82.3%,23.7%and 82.3%at class level,respectively.Hence,it can be stated that thanks to the relative facility of conventional soil survey compared with geostatistical methods,this method can be expressed as a preferable way for handling a usual land suitability evaluation design;but using soil map units as land suitability delineations may lead to unsatisfactory results in estimation of quantity and type of existing limitations.
