Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District

Accurate soil maps are essential for soil protection, management, and digital agriculture. However, traditional soil maps often lack the detail required for local applications, while farm-scale surveys are often not economically viable. This study uses legacy soil data and digital soil mapping (DSM)...

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Main Authors: Monica Zanini, Uta Heiden, Leonardo Pace, Raffaele Casa, Simone Priori
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/1/89
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author Monica Zanini
Uta Heiden
Leonardo Pace
Raffaele Casa
Simone Priori
author_facet Monica Zanini
Uta Heiden
Leonardo Pace
Raffaele Casa
Simone Priori
author_sort Monica Zanini
collection DOAJ
description Accurate soil maps are essential for soil protection, management, and digital agriculture. However, traditional soil maps often lack the detail required for local applications, while farm-scale surveys are often not economically viable. This study uses legacy soil data and digital soil mapping (DSM) to produce accurate, low-cost maps of key soil properties, namely clay, sand, total lime (CaCO<sub>3</sub>), organic carbon (SOC), total nitrogen (TN), and the cation-exchange capacity (CEC). The DSM procedure involved multivariate stepwise regression kriging that uses the terrain attributes and bare soil reflectance composite (SRC) from Sentinel-2 multitemporal images. The procedure to obtain the SRC was carried out following the Soil Composite Mapping Processor (SCMaP) methodology. The Sentinel-2 bands of the SRC showed strong correlations with soil features, making them very suitable explicative variables for regression kriging. In particular, the SWIR bands (b11 and b12) were important covariates in predicting clay, sand, and CEC maps. The accuracy of the regression models was very good for clay, sand, SOC, and CEC (R<sup>2</sup> > 0.90), while CaCO<sub>3</sub> showed lower accuracy (R<sup>2</sup> = 0.67). Normalization of SOC, TN, and CaCO<sub>3</sub> did not significantly improve the prediction accuracy, except for SOC, which showed a slight improvement. In addition, a supervised classification approach was applied to predict soil typological units (STUs) using the mapped soil attributes. This methodology demonstrates the potential of SRCs and regression kriging to produce detailed soil property maps to support precision agriculture and sustainable land management.
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spelling doaj-art-baca855841054a57a2f35da9033ebc852025-01-10T13:20:11ZengMDPI AGRemote Sensing2072-42922024-12-011718910.3390/rs17010089Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland DistrictMonica Zanini0Uta Heiden1Leonardo Pace2Raffaele Casa3Simone Priori4Department of Agriculture and Forest Sciences, University of Tuscia, Via San Camillo de Lellis, 01100 Viterbo, ItalyGerman Aerospace Center (DLR), The Remote Sensing Technology Institute, Muenchener Str. 20, 82234 Wessling, GermanyDepartment of Agriculture and Forest Sciences, University of Tuscia, Via San Camillo de Lellis, 01100 Viterbo, ItalyDepartment of Agriculture and Forest Sciences, University of Tuscia, Via San Camillo de Lellis, 01100 Viterbo, ItalyDepartment of Agriculture and Forest Sciences, University of Tuscia, Via San Camillo de Lellis, 01100 Viterbo, ItalyAccurate soil maps are essential for soil protection, management, and digital agriculture. However, traditional soil maps often lack the detail required for local applications, while farm-scale surveys are often not economically viable. This study uses legacy soil data and digital soil mapping (DSM) to produce accurate, low-cost maps of key soil properties, namely clay, sand, total lime (CaCO<sub>3</sub>), organic carbon (SOC), total nitrogen (TN), and the cation-exchange capacity (CEC). The DSM procedure involved multivariate stepwise regression kriging that uses the terrain attributes and bare soil reflectance composite (SRC) from Sentinel-2 multitemporal images. The procedure to obtain the SRC was carried out following the Soil Composite Mapping Processor (SCMaP) methodology. The Sentinel-2 bands of the SRC showed strong correlations with soil features, making them very suitable explicative variables for regression kriging. In particular, the SWIR bands (b11 and b12) were important covariates in predicting clay, sand, and CEC maps. The accuracy of the regression models was very good for clay, sand, SOC, and CEC (R<sup>2</sup> > 0.90), while CaCO<sub>3</sub> showed lower accuracy (R<sup>2</sup> = 0.67). Normalization of SOC, TN, and CaCO<sub>3</sub> did not significantly improve the prediction accuracy, except for SOC, which showed a slight improvement. In addition, a supervised classification approach was applied to predict soil typological units (STUs) using the mapped soil attributes. This methodology demonstrates the potential of SRCs and regression kriging to produce detailed soil property maps to support precision agriculture and sustainable land management.https://www.mdpi.com/2072-4292/17/1/89precision agricultureSentinel-2multitemporal imagessoil organic carbonsoil monitoring
spellingShingle Monica Zanini
Uta Heiden
Leonardo Pace
Raffaele Casa
Simone Priori
Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District
Remote Sensing
precision agriculture
Sentinel-2
multitemporal images
soil organic carbon
soil monitoring
title Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District
title_full Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District
title_fullStr Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District
title_full_unstemmed Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District
title_short Soil Reflectance Composite for Digital Soil Mapping in a Mediterranean Cropland District
title_sort soil reflectance composite for digital soil mapping in a mediterranean cropland district
topic precision agriculture
Sentinel-2
multitemporal images
soil organic carbon
soil monitoring
url https://www.mdpi.com/2072-4292/17/1/89
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AT utaheiden soilreflectancecompositefordigitalsoilmappinginamediterraneancroplanddistrict
AT leonardopace soilreflectancecompositefordigitalsoilmappinginamediterraneancroplanddistrict
AT raffaelecasa soilreflectancecompositefordigitalsoilmappinginamediterraneancroplanddistrict
AT simonepriori soilreflectancecompositefordigitalsoilmappinginamediterraneancroplanddistrict