M. Guevara, G. F. Olmedo, E. Stell, Y. Yigini, Y. Aguilar Duarte, C. Arellano Hernández, G. E. Arévalo, C. E. Arroyo-Cruz, A. Bolivar, S. Bunning, N. Bustamante Cañas, C. O. Cruz-Gaistardo, F. Davila, M. Dell Acqua, A. Encina, H. Figueredo Tacona, F. Fontes, J. A. Hernández Herrera, A. R. Ibelles Navarro, V. Loayza, A. M. Manueles, F. Mendoza Jara, C. Olivera, R. Osorio Hermosilla, G. Pereira, P. Prieto, I. A. Ramos, J. C. Rey Brina, R. Rivera, J. Rodríguez-Rodríguez, R. Roopnarine, A. Rosales Ibarra, K. A. Rosales Riveiro, G. A. Schulz, A. Spence, G. M. Vasques, R. R. Vargas, R. Vargas, MARIO GUEVARA, University of Delaware, ADRIANA BOLIVAR, Subdirección Agrología, Instituto Geográfico Agustín Codazzi, Bogotá, Colombia, SALLY BUNNING, Oficina Regional de la FAO para América Latina y el Caribe, Santiago de Chile, Chile, NELSON BUSTAMANTE CAÑAS, Servicio Agrícola y Ganadero, Santiago de Chile, Chile, CARLOS OMAR CRUZ-GAISTARDO, Instituto Nacional de Estadísitica y Geografía, Aguascalientes, Mexico, FABIAN DAVILLA, Ministerio de Ganaderia, Agricultura y Pesca, Montevideo, Uruguay, MARTIN DELL ACQUA, Ministerio de Ganaderia, Agricultura y Pesca, Montevideo, Uruguay, ARNULFO ENCINA, Facultad de Ciencias Agrarias de la Universidad Nacional de Asunción, Asunción, Paraguay, HERNÁN FIGUEREDO TACONA, Land Viceministry, Ministry of Rural Development and Land, La Paz, Bolivia, FERNANDO FONTES, Ministerio de Ganaderia, Agricultura y Pesca, Montevideo, Uruguay, JOSÉ ANTONIO HERNÁNDEZ HERRERA, Universidad Autónoma Agraria Antonio Narro Unidad Laguna, Torreón, Mexico, ALEJANDRO ROBERTO IBELLES NAVARRO, Instituto Nacional de Estadísitica y Geografía, Aguascalientes, Mexico, IVÁN ALEXIS RAMOS, Instituto de Investigación Agropecuaria de Panamá, Panamá, ALEXANDRA M. MANUELES, Zamorano University of Honduras and Asociación Hondureña de la Ciencia del Suelo, Tegucigalpa, Honduras, FERNANDO MENDOZA JARA, Universidad Nacional Agraria, Managua, Nicaragua, CAROLINA OLIVERA, Oficina Regional de la FAO para América Latina y el Caribe, Bogotá, Colombia, RODRIGO OSORIO HERMOSILLA, Servicio Agrícola y Ganadero, Santiago de Chile, Chile, GONZALO PEREIRA, Ministerio de Ganaderia, Agricultura y Pesca, Montevideo, Uruguay, PABLO PIETRO, Ministerio de Ganaderia, Agricultura y Pesca, Montevideo, Uruguay, VERONICA LOAYZA, Ministerio de Agricultura y Ganaderia, Quito, Ecuador, JUAN CARLOS REY BRINA, Sociedad Venezolana de la Ciencia del Suelo, Caracas, Venezuela, RAFAEL RIVERA, Ministerio de Medio Ambiente, Santo Domingo, Dominican Republic, JAVIER RODRÍGUEZ-RODRÍGUEZ, National Commission for the Knowledge and Use of Biodiversity, Mexico City, Mexico, RONALD ROOPNARINE, Department of Natural and Life Sciences, COSTAATT, Port of Spain, Trinidad an Tobago/University of the West Indies, St. Augustine Campus, Trinidad and Tobago, ALBÁN ROSALES IBARRA, Instituto de Innovación en Transferencia y Tecnología Agropecuaria, San José, Costa Rica, KENSET AMAURY ROSALES RIVEIRO, Ministerio de Ambiente y Recursos Naturales de Guatemala, Ciudad Guatemala, Guatemala, ADRIAN SPENCE, International Centre for Environmental and Nuclear Sciences, University of the West Indies, Kingston, Jamaica, RONALD R. VARGAS, FAO, Vialle de Terme di Caracalla, Rome, Italy, RODRIGO VARGAS, University of Delaware, Department of Plant and Soil Sciences, Newark, DE, USA., GUSTAVO DE MATTOS VASQUES, CNPS, GUILLERMO ANDRÉS SCHULZ, INTA CNIA, Buenos Aires, Argentina, GUILLERMO FEDERICO OLMEDO, INTA EEA Mendoza/FAO, EMMA STELL, University of Delaware, YUSUF YIGINI, FAO, YAMELI AGUILAR DUARTE, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Mérida, Mexico, CARLOS ARELLANO HERNÁNDEZ, Instituto Nacional de Estadísitica y Geografía, Aguascalientes, Mexico, GLORIA E. ARÉVALO, Zamorano University of Honduras and Asociación Hondureña de la Ciencia del Suelo, Tegucigalpa, Honduras, and CARLOS EDUARDO ARROYO-CRUZ, National Commission for the Knowledge and Use of Biodiversity, Mexico City, Mexico
Country-specific soil organic carbon (SOC) estimates are the baseline for the Global SOC Map of the Global Soil Partnership (GSOCmap-GSP). This endeavor is key to explaining the uncertainty of global SOC estimates but requires harmonizing heterogeneous datasets and building country-specific capacities for digital soil mapping (DSM).We identified country-specific predictors for SOC and tested the performance of five predictive algorithms for mapping SOC across Latin America. The algorithms included support vector machines (SVMs), random forest (RF), kernel-weighted nearest neighbors (KK), partial least squares regression (PL), and regression kriging based on stepwise multiple linear models (RK). Country-specific training data and SOC predictors (5 5 km pixel resolution) were obtained from ISRIC – World Soil Information. Temperature, soil type, vegetation indices, and topographic constraints were the best predictors for SOC, but country-specific predictors and their respective weights varied across Latin America. We compared a large diversity of country-specific datasets and models, and were able to explain SOC variability in a range between 1 and 60 %, with no universal predictive algorithm among countries. A regional (nD11 268 SOC estimates) ensemble of these five algorithms was able to explain 39% of SOC variability from repeated 5-fold cross-validation.We report a combined SOC stock of 77.8 43.6 Pg (uncertainty represented by the full conditional response of independent model residuals) across Latin America. SOC stocks were higher in tropical forests (30 16.5 Pg) and croplands (13 8.1 Pg). Country-specific and regional ensembles revealed spatial discrepancies across geopolitical borders, higher elevations, and coastal plains, but provided similar regional stocks (77.8 42.2 and 76.8 45.1 Pg, respectively). These results are conservative compared to global estimates (e.g., SoilGrids250m 185.8 Pg, the Harmonized World Soil Database 138.4 Pg, or the GSOCmap-GSP 99.7 Pg). Countries with large area (i.e., Brazil, Bolivia, Mexico, Peru) and large spatial SOC heterogeneity had lower SOC stocks per unit area and larger uncertainty in their predictions. We highlight that expert opinion is needed to set boundary prediction limits to avoid unrealistically high modeling estimates. For maximizing explained variance while minimizing prediction bias, the selection of predictive algorithms for SOC mapping should consider density of available data and variability of country-specific environmental gradients. This study highlights the large degree of spatial uncertainty in SOC estimates across Latin America. We provide a framework for improving country-specific mapping efforts and reducing current discrepancy of global, regional, and country-specific SOC estimates. Fil: Guevara, Mario. Universidad de Delaware. Department of Plant and Soil Sciences; Estados Unidos Fil: Olmedo, Guillermo Federico. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina. FAO; Italia Fil: Stell; Emma. University of Delaware, Department of Plant and Soil Sciences; Estados Unidos Fil: Yigini, Yusuf. FAO; Italia Fil: Aguilar Duarte, Yameli. Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias; México Fil: Arellano Hernández, Carlos. Instituto Nacional de Estadísitica y Geografía; México Fil: Arévalo, Gloria E. Zamorano. University of Honduras and Asociación Hondureña de la Ciencia del Suelo; Honduras Fil: Arroyo-Cruz, Carlos Eduardo. National Commission for the Knowledge and Use of Biodiversity; México Fil: Bolivar, Adriana. Instituto Geográfico Agustín Codazzi. Subdirección Agrología; Colombia Fil: Bunning, Sally. FAO. Oficina Regional para América Latina y el Caribe; Chile Fil: Bustamante Cañas, Nelson. Servicio Agrícola y Ganadero; Chile Fil: Cruz-Gaistardo, Carlos Omar. Instituto Nacional de Estadísitica y Geografía; México Dell Acqua, Martín. Ministerio de Ganadería, Agricultura y Pesca. Dirección General de Recursos Naturales; Uruguay Fil: Encina, Arnulfo. Universidad Nacional de Asunción. Facultad de Ciencias Agrarias; Paraguay Fil: Figueredo Tacona, Hernán. Ministry of Rural Development and Land. Land Viceministry; Bolivia Fil: Fontes, Fernando. Ministerio de Ganadería, Agricultura y Pesca. Dirección General de Recursos Naturales; Uruguay Fil: Hernández Herrera, José Antonio. Universidad Autónoma Agraria Antonio Narro. Unidad Laguna; México Fil: Ibelles Navarro, Alejandro Roberto. Instituto Nacional de Estadísitica y Geografía; México Fil: Loayza, Verónica. Ministerio de Agricultura y Ganaderia; Ecuador Fil: Manueles, Alexandra M.. Zamorano University of Honduras and Asociación Hondureña de la Ciencia del Suelo; Honduras Fil: Mendoza Jara, Fernando . Universidad Nacional Agraria; Nicaragua Fil: Olivera, Carolina. FAO. Oficina Regional para América Latina y el Caribe; Colombia Fil: Osorio Hermosilla, Rodrigo. Servicio Agrícola y Ganadero; Chile Fil: Pereira, Gonzalo. Ministerio de Ganadería, Agricultura y Pesca. Dirección General de Recursos Naturales; Uruguay Fil: Prieto, Pablo. Ministerio de Ganadería, Agricultura y Pesca. Dirección General de Recursos Naturales; Uruguay Fil: Ramos, Iván Alexis . Instituto de Investigación Agropecuaria de Panamá; Panamá Fil: Rey Brina, Juan Carlos. Sociedad Venezolana de la Ciencia del Suelo; Venezuela Fil: Rivera, Rafael. Ministerio de Medio Ambiente; República Dominicana Fil: Rodríguez-Rodríguez, Javier. National Commission for the Knowledge and Use of Biodiversity; México Fil: Roopnarine, Ronald. Department of Natural and Life Sciences. COSTAATT; Trinidad y Tobago Fil: Rosales Ibarra, Albán. Instituto de Innovación en Transferencia y Tecnología Agropecuaria; Costa Rica Fil: Rosales Riveiro, Kenset Amaury. Ministerio de Ambiente y Recursos Naturales de Guatemala; Guatemala Fil: Schulz, Guillermo Andrés. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; Argentina Fil: Spence, Adrián. University of the West Indies. International Centre for Environmental and Nuclear Sciences; Jamaica Fil: Vasques, Gustavo M. EMBRAPA Solos; Brasil Fil: Vargas, Ronald R. FAO; Italia Fil: Vargas, Rodrigo. University of Delaware. Department of Plant and Soil Sciences; Estados Unidos