Using SAR-based products to calculate potato carbon uptake in a tropical Andean region

ABSTRACT

Gross primary productivity (GPP) is an essential parameter to estimate the efficiency of carbon transfer in terrestrial ecosystems. The daily GPP has been monitored in the past using mainly optical satellite imagery. However, GPP has never been monitored using satellite Synthetic Aperture Radar (SAR) imagery. We evaluate the possibility of using Sentinel-1 SAR data to estimate GPP and compare with field GPP measurements using eddy covariance (EC) systems in three commercial potato fields, located in the Andean region of Colombia, using three different water irrigation levels. Raw and processed radar data from Sentinel-1 were compared with the daily and accumulated GPP from the EC. Results indicate that SAR data has a high correlation with the accumulated GPP measured by the EC in the field. The normalized radar backscatter and radar brilliance coefficients with VH polarization show a good correlation with the EC accumulated GPP in irrigated potato fields (R²: 0.77–0.81), while radar vegetation indices show a good correlation with the EC accumulated GPP in potato fields with no irrigation (R²≈0.82). In particular, the accumulated GPP during the whole potato crop cycle was estimated with good accuracy (~5% error with irrigation and ~10% error with no irrigation).

KEYWORDS:

• Synthetic aperture radar
• eddy covariance
• vegetation indices
• gross primary productivity
• solanum tuberosum L
• Sentinel-1

Acknowledgments

This work is part of a larger project in Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA) named Sistema de Información Agroclimática del cultivo de la papa en la región de Cundinamarca, Colombia (SIAP). We thank, Fabio Ernesto Martínez Maldonado for his contribution to data analysis, Zahara Lasso, Douglas Gómez, Jose Alfredo Molina Varón, Pablo Edgar Jiménez, Óscar Dubán Ocampo Páez, and Jhon Alexander Martínez Morales, for their contribution in the equipment installation process, and farmers Santiago Forero, Wilson Forero, and Alejandro Forero for providing a suitable lot for the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data presented in this study are available upon request from the Agrosavia Intellectual Property Department. The data are not publicly available due to Agrosavia’s copyright. Your request can be sent to [email protected].

Additional information

Funding

This research was funded by the Fondo de Ciencia, Tecnología e Innovación del Sistema General de Regalías, administered by the Fondo Nacional de Financiación para Ciencia, Tecnología e Innovación—Francisco José de Caldas, Programa Colombia BIO, Gobernación de Cundinamarca and Ministerio de Ciencia, Tecnología e Innovación [MINCIENCIAS] funding number [66153], and Corporación Colombiana de Investigación Agropecuaria [AGROSAVIA] funding number TV19 1000911.