Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam
Soil property maps are essential resources for agricultural land use. However, soil properties mapping is costly and time-consuming, especially in the regions with complicated topographic conditions. This study was conducted in a hilly region of Central Vietnam with the following objectives: (i) to...
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MDPI AG
2019-03-01
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| Series: | ISPRS International Journal of Geo-Information |
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| Online Access: | http://www.mdpi.com/2220-9964/8/3/147 |
| _version_ | 1818110680299995136 |
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| author | Tung Gia Pham Martin Kappas Chuong Van Huynh Linh Hoang Khanh Nguyen |
| author_facet | Tung Gia Pham Martin Kappas Chuong Van Huynh Linh Hoang Khanh Nguyen |
| author_sort | Tung Gia Pham |
| collection | DOAJ |
| description | Soil property maps are essential resources for agricultural land use. However, soil properties mapping is costly and time-consuming, especially in the regions with complicated topographic conditions. This study was conducted in a hilly region of Central Vietnam with the following objectives: (i) to evaluate the best environmental variables to estimate soil organic carbon (SOC), total nitrogen (TN), and soil reaction (pH) with a regression kriging (RK) model, and (ii) to compare the accuracy of the ordinary kriging (OK) and RK methods. SOC, TN, and soil pH data were measured at 155 locations within the research area with a sampling grid of 2 km × 2 km for a soil layer from 0 to 30 cm depth. From these samples, 117 were used for interpolation, and the 38 randomly remaining samples were used for evaluating accuracy. The chosen environmental variables are land use type (LUT), topographic wetness index (TWI), and transformed soil adjusted vegetation index (TSAVI). The results indicate that the LUT variable is more effective than TWI and TSAVI for determining TN and pH when using the RK method, with a variance of 7.00% and 18.40%, respectively. In contrast, a combination of the LUT and TWI variables is the best for SOC mapping with the RK method, with a variance of 14.98%. The OK method seemed more accurate than the RK method for SOC mapping by 3.33% and for TN mapping by 10% but the RK method was found more precise than the OK method for soil pH mapping by 1.81%. Further selection of auxiliary variables and higher sampling density should be considered to improve the accuracy of the RK method. |
| first_indexed | 2024-12-11T02:51:00Z |
| format | Article |
| id | doaj.art-281b6b0bf5df46728d202bc48fd6e2de |
| institution | Directory Open Access Journal |
| issn | 2220-9964 |
| language | English |
| last_indexed | 2024-12-11T02:51:00Z |
| publishDate | 2019-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | ISPRS International Journal of Geo-Information |
| spelling | doaj.art-281b6b0bf5df46728d202bc48fd6e2de2022-12-22T01:23:17ZengMDPI AGISPRS International Journal of Geo-Information2220-99642019-03-018314710.3390/ijgi8030147ijgi8030147Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central VietnamTung Gia Pham0Martin Kappas1Chuong Van Huynh2Linh Hoang Khanh Nguyen3Cartography, GIS and Remote Sensing Department, Göttingen University, 37077 Göttingen, GermanyCartography, GIS and Remote Sensing Department, Göttingen University, 37077 Göttingen, GermanyPresidential Board, Hue University, 0234 Hue, VietnamInternational School, Hue University, 0234 Hue, VietnamSoil property maps are essential resources for agricultural land use. However, soil properties mapping is costly and time-consuming, especially in the regions with complicated topographic conditions. This study was conducted in a hilly region of Central Vietnam with the following objectives: (i) to evaluate the best environmental variables to estimate soil organic carbon (SOC), total nitrogen (TN), and soil reaction (pH) with a regression kriging (RK) model, and (ii) to compare the accuracy of the ordinary kriging (OK) and RK methods. SOC, TN, and soil pH data were measured at 155 locations within the research area with a sampling grid of 2 km × 2 km for a soil layer from 0 to 30 cm depth. From these samples, 117 were used for interpolation, and the 38 randomly remaining samples were used for evaluating accuracy. The chosen environmental variables are land use type (LUT), topographic wetness index (TWI), and transformed soil adjusted vegetation index (TSAVI). The results indicate that the LUT variable is more effective than TWI and TSAVI for determining TN and pH when using the RK method, with a variance of 7.00% and 18.40%, respectively. In contrast, a combination of the LUT and TWI variables is the best for SOC mapping with the RK method, with a variance of 14.98%. The OK method seemed more accurate than the RK method for SOC mapping by 3.33% and for TN mapping by 10% but the RK method was found more precise than the OK method for soil pH mapping by 1.81%. Further selection of auxiliary variables and higher sampling density should be considered to improve the accuracy of the RK method.http://www.mdpi.com/2220-9964/8/3/147land useordinary krigingregression krigingsoil propertiesCentral Vietnam |
| spellingShingle | Tung Gia Pham Martin Kappas Chuong Van Huynh Linh Hoang Khanh Nguyen Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam ISPRS International Journal of Geo-Information land use ordinary kriging regression kriging soil properties Central Vietnam |
| title | Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam |
| title_full | Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam |
| title_fullStr | Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam |
| title_full_unstemmed | Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam |
| title_short | Application of Ordinary Kriging and Regression Kriging Method for Soil Properties Mapping in Hilly Region of Central Vietnam |
| title_sort | application of ordinary kriging and regression kriging method for soil properties mapping in hilly region of central vietnam |
| topic | land use ordinary kriging regression kriging soil properties Central Vietnam |
| url | http://www.mdpi.com/2220-9964/8/3/147 |
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