Fine-scale soil mapping with Earth Observation data: a multiple geographic level comparison

Author(s)

Safanelli, Jose Lucas ^[1] ; Melo Dematte, Jose Alexandre ^[1] ; dos Santos, Natasha Valadares ^[1] ; Rosas, Jorge Tadeu Fim ^[1] ; Quinonez Silvero, Nelida Elizabet ^[1] ; Bonfatti, Benito Roberto ^[2] ; Mendes, Wanderson de Sousa ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Ciencia Solo, Escolar Super Agr Luiz de Queiroz, Piracicaba, SP - Brazil

^[2] Univ Estado Minas Gerais, Unidade Passos, Passos, MG - Brazil

• Document type: Journal article
• Source: Revista Brasileira de Ciência do Solo; v. 45, 2021.
• Web of Science Citations: 0

Abstract

ABSTRACT Multitemporal collections of satellite images and their products have recently been explored in digital soil mapping. This study aimed to produce a bare soil image (BSI) for the São Paulo State (Brazil) to perform a pedometric analysis for different geographical levels. First, we assessed the potential of the BSI for predicting the surface (0.00-0.20 m) and subsurface (0.80-1.00 m) clay, iron oxides (Fe 2 O 3 ), aluminum (m%) and bases saturation (V%) contents at the state level, which are important properties for soil classification. In this task, legacy soil samples, the BSI and terrain attributes were employed in machine learning. In a second moment, we evaluated the capacity of the BSI for clustering the landscape at the regional level, comparing the predicted patterns with a legacy semi-detailed soil map from a smaller reference site. In the final stage, the predicted soil maps from the state level were investigated at the farm level considering several sites distributed across the São Paulo state. Our results demonstrated that clay and Fe 2 O 3 reached the best prediction performance for both depths at the state level, reaching a RMSE of less than 10 %, RPIQ higher than 1.6 and R 2 of at least 0.41. Additionally, the predicted landscape clusters had a significant association with the main pedological classes, subsurface color, soil mineralogy and texture from the legacy semi-detailed soil map. Illustrative examples at the farm level indicated great capacity of BSI in detecting the variations of soils, which were linked to several soil properties, such as texture, iron content, drainage network, among others. Therefore, this study demonstrates that BSI is valuable information derived from optical Earth Observation data that can contribute to the future of soil survey and mapping in Brazil (PronaSolos). (AU)

• FAPESP's process: 16/01597-9 - Pedotransfer functions by geotecnologies associated with photopedology for pedological mapping in agricultural areas of São Paulo State
• Grantee: José Lucas Safanelli
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 14/22262-0 - Geotechnologies on a detailed digital soil mapping and the Brazilian soil spectral library: development and applications
• Grantee: José Alexandre Melo Demattê
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/21356-1 - Geotechnologies for mapping agricultural soils of São Paulo state
• Grantee: José Lucas Safanelli
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)