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Original Article | Open Access

Carbon Footprints

Diaz-Vallejo et al. Carbon Footprints 2026, 5, 12 DOI:10.20517/cf.2025.103

Defining soil carbon benchmark values of
agroecosystems across a diversity of tropical soil
environments

Emily J. Diaz-Vallejo 1,2 , Elliot Vaughan 3 , David Sotomayor , Manuel Matos , Samuel Rios , Carmen
5
4
5
Santiago , Erika Marin-Spiotta 1
5
Keywords:
Soil organic carbon, land-use
change, benchmark
modeling, agroecosystems

Citation: Diaz-Vallejo, E. J.;
Vaughan, E.; Sotomayor, D.;
Matos, M.; Rios, S.;
Santiago, C.;
Marin-Spiotta, E. Defining
soil carbon benchmark
values of agroecosystems
across a diversity of tropical
soil environments. Carbon
Footprints 2026, 5, 12.
https://dx.doi.org/10.20517
/cf.2025.103
Received: 31 Oct 2025
First Decision: 26 Dec Abstract
2025 Soil organic carbon (SOC) plays an important role in carbon and nutrient cycling,
Revised: 23 Jan 2026 agricultural productivity, and climate regulation, yet its variability and environmental
Accepted: 12 Feb 2026 controls remain poorly constrained in tropical regions characterized by a diversity of soils,
Published: 16 Mar 2026
climates, and land-use histories. We conducted a regional-scale assessment of SOC across
Academic Editors: Puerto Rico to evaluate how land use, soil properties, and climate influence SOC variability
Dafeng Hui, Adrian Unc and to examine the applicability of existing benchmark frameworks in tropical
Copy Editor: agroecosystems. We compiled SOC data from 586 soil pedons representing nine US
Ping Zhang
Production Editor: Department of Agriculture (USDA) soil orders and multiple land-use categories, with SOC
Ping Zhang concentrations standardized to the 0-30 cm depth. We evaluated land-use effects and
relationships between SOC and environmental variables. SOC concentrations differed by
land use, with greater values generally observed in wetlands and forests, intermediate
values in pastures or grazing lands, and lower values in agricultural lands. Environmental
factors associated with SOC variability differed by land use, with climate and soil suborder

1 Department of Geography, University of Wisconsin-Madison, Madison, WI 53706, USA.
2 College of Agriculture and Consumer Economics, University of Illinois, Urbana-Champaign, IL 61801, USA.
3 Environmental Science Program, Southwest Minnesota State University, Marshall, MN 56258, USA.
4 College of Agricultural Sciences, University of Puerto Rico, Mayagüez, PR 00681-9000, USA.
5 Natural Resources Conservation Service, United Stated Department of Agriculture, San Juan, PR 00918-4129, USA.

Correspondence to: Emily J. Diaz-Vallejo, Department of Geography, University of Wisconsin-Madison, Madison, WI 53706, USA. E-mail:
ejdiaz3@illinois.edu

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