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Communication dans un congrès

Spatial prediction of topsoil texture in Region Centre (France) combining regression and area-to-point kriging

Abstract : Land use and agricultural practices, in interaction with soil texture, influence soil fauna and soil microbial community, water holding capacity, and C and nutrient cycling among other agroecosystem properties. Detailed knowledge on the spatial distribution of soil texture can improve land-use planning and crop management. Our objective was to predict soil texture in agricultural land for the Region Centre (France), combining regression models and area-to-point kriging. The French soil-test database (BDAT) is largely populated with topsoil analyses requested by farmers mainly interested in soil fertility. To protect the anonymity of the farms, their coordinates are unknown and all measurements are aggregated by municipality. The nature of the data requires novel disaggregation techniques (i.e., area-to-point kriging) to develop high-resolution maps on point support. We applied an additive log-ratio transformation (alr-transform) on texture data to account for the compositional constraint (i.e. that the sum of sand, silt and clay contents must be 100 %) and achieve normality. Average values of 25 environmental covariates by municipality were used to fit predictive models with multiple linear regression, Cubist, and boosted regression trees (BRT). Data from 104 plots from the systematic soil quality monitoring network (RMQS) were used for independent validation. Only BRT models provided better predictions (clay-alr R2 = 0.54, sand-alr R2 = 0.76) than reference BDAT texture values averaged by commune (clay-alr R2 = 0.33, sand-alr R2 = 0.64). In a second step, BRT predictions were used as auxiliary variables for area-to-point kriging following the summary statistics approach developed by Orton et al. (2012). To deal with the dependence between clay- and sand-alr transforms we fitted a linear model of coregionalization, and applied area-to-point cokriging to the BRT residuals. This approach allowed us to include the relationships between soil forming factors and soil texture (through the BRT model), and to account for the uncertainty in the areal means, correlations between sand, silt and clay contents, and spatial autocorrelation (in the area-to-point cokriging step). We are currently testing whether incorporating remote sensing data (e.g., Landsat 8) in the regression models further improves soil texture predictions despite the loss of information when averaging by municipality. The combination of regression and area-to-point kriging is a promising method to produce high-resolution maps as expected in the GlobalSoilMap project from soil-test data missing the exact coordinates.
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Communication dans un congrès
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https://hal.inrae.fr/hal-02795867
Déposant : Migration Prodinra <>
Soumis le : vendredi 5 juin 2020 - 13:05:11
Dernière modification le : mardi 7 juillet 2020 - 15:44:19

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Pedometrics2015_1.pptx
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  • HAL Id : hal-02795867, version 1
  • PRODINRA : 326793

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Mercedes Roman Dobarco, Thomas G Orton, Nicolas Saby, Vera Laetitia Mulder, Sébastien Drufin, et al.. Spatial prediction of topsoil texture in Region Centre (France) combining regression and area-to-point kriging. Pedometrics 2015, Sep 2015, Cordoue, Spain. 13 p. ⟨hal-02795867⟩

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