Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.

Detalhes bibliográficos
Autor(a) principal: RODRIGUES, H. M.
Data de Publicação: 2020
Outros Autores: VASQUES, G. de M., OLIVEIRA, R. P. de, TAVARES, S. R. de L., CEDDIA, M. B., HERNANI, L. C.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1124782
https://doi.org/10.3390/soilsystems4030056
Resumo: Finding an ideal sampling design is a crucial stage in detailed soil mapping to assure reasonable accuracy of resulting soil property maps. This study aimed to evaluate the influence of sampling designs and sample sizes on the quality of soil apparent electrical conductivity (ECa) maps from an electromagnetic sensor survey. Twenty-six (26) parallel transects were gathered in a 72-ha plot in Southeastern Brazil. Soil ECa measurements using an on-the-go electromagnetic induction sensor were taken every second using sensor vertical orientation. Two approaches were used to reduce the sample size and simulate kriging interpolations of soil ECa. Firstly, the number of transect lines was reduced by increasing the distance between them; thus, 26 transects with 40 m spacing; 13 with 80 m; 7 with 150 m; and 4 with 300 m. Secondly, random point selection and Douglas-Peucker algorithms were used to derive four reduced datasets by removing 25, 50, 75, and 95% of the points from the ECa survey dataset. Soil ECa was interpolated at 5 m output spatial resolution using ordinary kriging and the four datasets from each simulation (a total of twelve datasets). Map uncertainty was assessed by root mean square error and mean error metrics from 400 random samples previously selected for external map validation. Maps were evaluated on their uncertainty and spatial structure of variation. The transect elimination approach showed that maps produced with transect spacing up to 150 m could preserve the spatial structure of ECa variations. Douglas-Peucker results showed lower nugget values than random point simulations for all selected sample densities, except for a 95% point reduction. The soil ECa maps derived from the 75% reduced dataset (by random sampling or Douglas-Peucker) or from 13 transect lines (80 m spacing) showed reasonable accuracy (RMSE of validation circa 0.7) relative to the map interpolated from all survey points (RMSE of 0.5), suggesting that transect spacing of 80 m and reading intervals greater than one second can be used for improving the efficiency of on-the-go soil ECa surveys.
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spelling Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.Sensoriamento proximal do soloGeoestatísticaKrigagemIncertezaSensoriamento RemotoRemote sensingGeostatisticsKrigingUncertaintyFinding an ideal sampling design is a crucial stage in detailed soil mapping to assure reasonable accuracy of resulting soil property maps. This study aimed to evaluate the influence of sampling designs and sample sizes on the quality of soil apparent electrical conductivity (ECa) maps from an electromagnetic sensor survey. Twenty-six (26) parallel transects were gathered in a 72-ha plot in Southeastern Brazil. Soil ECa measurements using an on-the-go electromagnetic induction sensor were taken every second using sensor vertical orientation. Two approaches were used to reduce the sample size and simulate kriging interpolations of soil ECa. Firstly, the number of transect lines was reduced by increasing the distance between them; thus, 26 transects with 40 m spacing; 13 with 80 m; 7 with 150 m; and 4 with 300 m. Secondly, random point selection and Douglas-Peucker algorithms were used to derive four reduced datasets by removing 25, 50, 75, and 95% of the points from the ECa survey dataset. Soil ECa was interpolated at 5 m output spatial resolution using ordinary kriging and the four datasets from each simulation (a total of twelve datasets). Map uncertainty was assessed by root mean square error and mean error metrics from 400 random samples previously selected for external map validation. Maps were evaluated on their uncertainty and spatial structure of variation. The transect elimination approach showed that maps produced with transect spacing up to 150 m could preserve the spatial structure of ECa variations. Douglas-Peucker results showed lower nugget values than random point simulations for all selected sample densities, except for a 95% point reduction. The soil ECa maps derived from the 75% reduced dataset (by random sampling or Douglas-Peucker) or from 13 transect lines (80 m spacing) showed reasonable accuracy (RMSE of validation circa 0.7) relative to the map interpolated from all survey points (RMSE of 0.5), suggesting that transect spacing of 80 m and reading intervals greater than one second can be used for improving the efficiency of on-the-go soil ECa surveys.HUGO MACHADO RODRIGUES, UFRRJ; GUSTAVO DE MATTOS VASQUES, CNPS; RONALDO PEREIRA DE OLIVEIRA, CNPS; SILVIO ROBERTO DE LUCENA TAVARES, CNPS; MARCOS BACIS CEDDIA, UFRRJ; LUIS CARLOS HERNANI, CNPS.RODRIGUES, H. M.VASQUES, G. de M.OLIVEIRA, R. P. deTAVARES, S. R. de L.CEDDIA, M. B.HERNANI, L. C.2020-09-09T04:36:30Z2020-09-09T04:36:30Z2020-09-082020info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleSoil Systems, v. 4, n. 3, 56, 2020.http://www.alice.cnptia.embrapa.br/alice/handle/doc/1124782https://doi.org/10.3390/soilsystems4030056enginfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)instname:Empresa Brasileira de Pesquisa Agropecuária (Embrapa)instacron:EMBRAPA2020-09-09T04:36:46Zoai:www.alice.cnptia.embrapa.br:doc/1124782Repositório InstitucionalPUBhttps://www.alice.cnptia.embrapa.br/oai/requestopendoar:21542020-09-09T04:36:46falseRepositório InstitucionalPUBhttps://www.alice.cnptia.embrapa.br/oai/requestcg-riaa@embrapa.bropendoar:21542020-09-09T04:36:46Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice) - Empresa Brasileira de Pesquisa Agropecuária (Embrapa)false
dc.title.none.fl_str_mv Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
title Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
spellingShingle Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
RODRIGUES, H. M.
Sensoriamento proximal do solo
Geoestatística
Krigagem
Incerteza
Sensoriamento Remoto
Remote sensing
Geostatistics
Kriging
Uncertainty
title_short Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
title_full Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
title_fullStr Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
title_full_unstemmed Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
title_sort Finding suitable transect spacing and sampling designs for accurate soil ECa mapping from EM38-MK2.
author RODRIGUES, H. M.
author_facet RODRIGUES, H. M.
VASQUES, G. de M.
OLIVEIRA, R. P. de
TAVARES, S. R. de L.
CEDDIA, M. B.
HERNANI, L. C.
author_role author
author2 VASQUES, G. de M.
OLIVEIRA, R. P. de
TAVARES, S. R. de L.
CEDDIA, M. B.
HERNANI, L. C.
author2_role author
author
author
author
author
dc.contributor.none.fl_str_mv HUGO MACHADO RODRIGUES, UFRRJ; GUSTAVO DE MATTOS VASQUES, CNPS; RONALDO PEREIRA DE OLIVEIRA, CNPS; SILVIO ROBERTO DE LUCENA TAVARES, CNPS; MARCOS BACIS CEDDIA, UFRRJ; LUIS CARLOS HERNANI, CNPS.
dc.contributor.author.fl_str_mv RODRIGUES, H. M.
VASQUES, G. de M.
OLIVEIRA, R. P. de
TAVARES, S. R. de L.
CEDDIA, M. B.
HERNANI, L. C.
dc.subject.por.fl_str_mv Sensoriamento proximal do solo
Geoestatística
Krigagem
Incerteza
Sensoriamento Remoto
Remote sensing
Geostatistics
Kriging
Uncertainty
topic Sensoriamento proximal do solo
Geoestatística
Krigagem
Incerteza
Sensoriamento Remoto
Remote sensing
Geostatistics
Kriging
Uncertainty
description Finding an ideal sampling design is a crucial stage in detailed soil mapping to assure reasonable accuracy of resulting soil property maps. This study aimed to evaluate the influence of sampling designs and sample sizes on the quality of soil apparent electrical conductivity (ECa) maps from an electromagnetic sensor survey. Twenty-six (26) parallel transects were gathered in a 72-ha plot in Southeastern Brazil. Soil ECa measurements using an on-the-go electromagnetic induction sensor were taken every second using sensor vertical orientation. Two approaches were used to reduce the sample size and simulate kriging interpolations of soil ECa. Firstly, the number of transect lines was reduced by increasing the distance between them; thus, 26 transects with 40 m spacing; 13 with 80 m; 7 with 150 m; and 4 with 300 m. Secondly, random point selection and Douglas-Peucker algorithms were used to derive four reduced datasets by removing 25, 50, 75, and 95% of the points from the ECa survey dataset. Soil ECa was interpolated at 5 m output spatial resolution using ordinary kriging and the four datasets from each simulation (a total of twelve datasets). Map uncertainty was assessed by root mean square error and mean error metrics from 400 random samples previously selected for external map validation. Maps were evaluated on their uncertainty and spatial structure of variation. The transect elimination approach showed that maps produced with transect spacing up to 150 m could preserve the spatial structure of ECa variations. Douglas-Peucker results showed lower nugget values than random point simulations for all selected sample densities, except for a 95% point reduction. The soil ECa maps derived from the 75% reduced dataset (by random sampling or Douglas-Peucker) or from 13 transect lines (80 m spacing) showed reasonable accuracy (RMSE of validation circa 0.7) relative to the map interpolated from all survey points (RMSE of 0.5), suggesting that transect spacing of 80 m and reading intervals greater than one second can be used for improving the efficiency of on-the-go soil ECa surveys.
publishDate 2020
dc.date.none.fl_str_mv 2020-09-09T04:36:30Z
2020-09-09T04:36:30Z
2020-09-08
2020
dc.type.driver.fl_str_mv info:eu-repo/semantics/publishedVersion
info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv Soil Systems, v. 4, n. 3, 56, 2020.
http://www.alice.cnptia.embrapa.br/alice/handle/doc/1124782
https://doi.org/10.3390/soilsystems4030056
identifier_str_mv Soil Systems, v. 4, n. 3, 56, 2020.
url http://www.alice.cnptia.embrapa.br/alice/handle/doc/1124782
https://doi.org/10.3390/soilsystems4030056
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.source.none.fl_str_mv reponame:Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
instname:Empresa Brasileira de Pesquisa Agropecuária (Embrapa)
instacron:EMBRAPA
instname_str Empresa Brasileira de Pesquisa Agropecuária (Embrapa)
instacron_str EMBRAPA
institution EMBRAPA
reponame_str Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
collection Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
repository.name.fl_str_mv Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice) - Empresa Brasileira de Pesquisa Agropecuária (Embrapa)
repository.mail.fl_str_mv cg-riaa@embrapa.br
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