About

Salvatore Calabrese is an Assistant Professor in the Department of Biological and Agricultural Engineering at Texas A&M University. His research addresses critical environmental challenges related to the impact of climatic changes and land management practices on the hydrologic cycle and the spatiotemporal dynamics of carbon and nutrient cycles in soil and throughout the Critical Zone. He develops mathematical models to quantify the sensitivity of hydrologic and biogeochemical cycles to environmental changes in natural and agricultural ecosystems, exploring innovative land management strategies for sustainability at both local and global scales. Calabrese's multidisciplinary approach integrates hydrology, biology, biogeochemistry, dynamical system theory, stochastic processes, and thermodynamics to study the interaction between human activities and ecosystems holistically. His current projects focus on the interaction between the carbon cycle, soil structure and properties, soil moisture dynamics, sustainable agricultural practices, large-scale water and carbon cycle interactions, soil microbial modeling, and enhanced weathering as a negative emissions technology. He has received several awards, including the Vice Chancellor's Award in Excellence for Early Career Research in 2024 and the Embassy of Italy Award, ISSNAF Young Investigator Awards in 2022.

Research topics

• Environmental science
• Geology
• Chemistry
• Geography
• Earth science
• Cartography
• Geomorphology
• Environmental chemistry
• Biology
• Ecology
• Soil science
• Geochemistry
• Atmospheric sciences

Selected publications

• Quantifying temperature dependence of Fe reduction in humid tropical soils: a Bayesian model-data integration

  2026-04-22

  articleOpen accessSenior author

  Abstract. Humid tropical forests are critical regulators of the global carbon (C) cycle, yet their soil C stocks are increasingly vulnerable to warming. Predicting potential losses requires a mechanistic understanding of the processes that govern soil C stabilization and mineralization, particularly in Fe-rich soils, where iron (Fe) redox cycling plays a dual role in both protecting and decomposing organic matter. However, the temperature dependency of these Fe-mediated processes remains poorly understood. In this study, we quantified the temperature dependence of FeIII reduction by conducting anoxic incubations at 23, 27, and 33 °C and calibrating four kinetic models of increasing complexity to estimate the Q10 and Arrhenius (Ea) using a Markov Chain Monte Carlo (MCMC) framework. Model performance was evaluated using Bayesian information criteria (WAIC, LOO, and LPML) to assess fit, complexity and uncertainty. Short-term warming significantly accelerated Fe-reduction rates, potentially destabilizing mineral-associated organic carbon and enhancing microbial respiration. Estimated Q10 and Ea values ranged from 1.5 to 2.1 and 30.8 to 56.5 kJ mol-1 respectively, comparable to the temperature sensitivity values measured in temperate and tropical biomes. With the available data, Bayesian information criteria preferred the simplest one pool FeII model due to its parsimony. In contrast, the most complex (three pool) model, which includes dissolved organic carbon (DOC) dynamics alongside Fe reduction and oxidation, was generally the least preferred by Bayesian information criteria due to increased uncertainty from unconstrained additional processes. These results underscore the importance of temperature-dependent Fe redox processes in regulating soil C cycle in humid tropical soils and emphasize the need to balance model complexity with data availability when modeling coupled C-Fe interactions.

  PublisherOA PDFDOI

• Expert elicitation on agricultural enhanced weathering reveals carbon dioxide removal potential and uncertainties in loss pathways

  Communications Earth & Environment · 2026-03-12

  articleOpen access

  Abstract Enhanced weathering in agriculture is a potential gigatonne-scale carbon dioxide removal (CDR) pathway, but its potential remains difficult to constrain. We used a formal expert elicitation process to estimate CDR potential and efficiency, uncertainties, and key data needs for six feedstocks. Expert opinion of global potential varied by feedstock, with estimates averaging 0.2-0.7 Gt CO2e/yr, but with a wide range (from a source to greater than 5 Gt CO2e/yr removal). When focusing on the American Midwest (pH 5.5-6), carbon dioxide removal efficiency, meaning the fraction of potential ultimately realized, ranged from 27-39%. Key uncertainties included feedstock availability, calcite saturation, and deep soil/freshwater emission pathways. There is a need for empirical data in key stages, with potential to leverage liming data where appropriate. Overall, there appears to be strong potential CDR at broad scales. However, continued research is necessary to build confidence when quantifying that potential and actual removals.

  PublisherOA PDFDOI

• Supplementary material to "Quantifying temperature dependence of Fe reduction in humid tropical soils: a Bayesian model-data integration"

  2026-04-22

  articleOpen accessSenior author

  Table S1.Calibrated values of reduction rate (r RED ), half saturation constants (K RED , K DOC ), coefficient (q maxfe ), and initial concentrations of Fe II , Fe III , Fe T ot and

  PublisherDOI

• Comparative Assessment of Regional Volcanic By-products and Olivine for Enhanced Weathering in Mediterranean Alkaline Soils

  2026-03-14

  articleOpen accessCorresponding

  Enhanced Weathering (EW) is gaining traction as a carbon dioxide removal (CDR)technology, yet its viable large-scale deployment requires balancing carbon sequestrationefficiency with agronomic, environmental, and economic costs and benefits. In thisstudy, we present the setup and preliminary insights from a mesocosm experimentcarried out at the University of Palermo (Italy), designed to compare the performance ofregional volcanic by-products against a commercial olivine benchmark. We utilized 32outdoor mesocosms (0.27 square meters each) arranged in a randomized block design,applying silicate amendments at a rate of 50 t/ha.The experiment compares three silicate materials with distinct physical and mineralogicalproperties: (i) basaltic mine waste from local quarrying (Dv50 of 38.7 microns), (ii) volcanicash from Mt. Etna—a sandy, highly porous material rich in amorphous silica with a low bulkdensity—and (iii) commercial olivine (Dv50 of 30.2 microns). These materials are applied toboth bare soil and soil vegetated with a mix of local forage legumes, allowing us to assessthe role of plant roots in driving the dynamics of weathering rates and the fate of weatheringproducts.We quantify the CDR potential by monitoring alkalinity, Dissolved Inorganic Carbon (DIC),and major cations (Mg2+, Ca2+, K+, Na+) in drainage waters. Crucially, we also analyzethe soil profile to monitor the precipitation of pedogenic carbonates and changes inexchangeable major cation pools to assess the long-term effects of the silicateamendments.Simultaneously, we monitor the biomass growth to identify potential fertilization benefits.We also assess the potential trade-offs of trace element release, specifically focusing onthe high Nickel (Ni) content inherent in olivine compared to the volcanic waste streams.Data collected will be used to calibrate the Soil Model for Enhanced Weathering (SMEW),bridging the gap between mesocosm-scale observations and numerical simulation torefine dissolution factors for the seasonally dry, alkaline soil conditions typical of theMediterranean.Using regional volcanic waste streams can provide a cost-effective and agronomicallyviable alternative to commercial minerals, delivering competitive CDR rates whilesupporting a circular economy and reducing the carbon footprint of mineral sourcing,grinding, and transport.

  PublisherDOI

• Efficacy of advanced Fenton-photo systems for the degradation of petroleum hydrocarbons using complex neural networks

  RSC Advances · 2026-01-01

  articleOpen access

  ratio, with degradation mechanisms varying based on PAH structure. This AI-driven optimization provides an efficient framework for soil remediation in petroleum-contaminated desert environments where traditional methods face significant challenges.

  PublisherOA PDFDOI

• Soil Structure and Mixing Controls on Water‐Rock Contact: Implications for Enhanced Weathering

  Water Resources Research · 2026-02-01

  articleOpen accessSenior author

  Abstract Enhanced weathering (EW), the addition of finely ground silicate rock powder (RP) to soil, has emerged as a promising carbon removal strategy. However, quantifying weathering rates in soils remains challenging, as most continuum‐scale EW models do not adequately account for the fraction of RP surface area (SA) that is wet at a given soil moisture and thus actively weathering. Here, we study how soil pore structure, RP particle size distribution, and RP mixing degree within the soil control water‐rock contact. Using a soil‐physics‐based framework, we derive a scaling factor that quantifies the wet fraction of RP SA as a function of soil moisture and mixing degree within soil pores. This scaling factor varies nonlinearly with soil moisture for typical soil pore structures and RP particle size distributions, countering previous zero‐order (independent of soil moisture) or linear assumptions. The scaling factor evolves dynamically with hydrological fluctuations and, for a given pore structure and RP mixing degree, it can span nearly two orders of magnitude with changes in median particle size. To illustrate its application, we integrate the derived scaling factor into the Soil Model for Enhanced Weathering and examine the sensitivity of simulated weathering fluxes to mixing degree under otherwise identical conditions. Under low mixing, results show that average weathering rates are roughly two orders of magnitude lower than under perfect mixing over 1 year of application. Our work provides a mechanistic, computationally efficient framework for representing water‐rock contact in soil, offering a pathway to improve continuum‐scale EW models.

  PublisherOA PDFDOI

• EcoHydrology, Thermodynamics, and Microbial Ecology at the onset of soil syntrophy

  2026-03-14

  articleOpen accessCorresponding

  Syntrophy is metabolic cross-feeding in which an upstream organism can oxidize a substrate only because a partner continuously removes inhibitory products (often H2), making the overall reaction energetically favorable. In soils, moisture regulates anaerobic microbial interactions by shaping oxygen availability and gas diffusivity, while fermentation produces reduced intermediates, including volatile fatty acids (VFAs) such as butyrate and propionate, whose oxidation is endergonic under standard conditions and becomes feasible only when hydrogen is maintained sufficiently low by hydrogenotrophic methanogens. Here we present a minimalist predator–prey model that captures the key feedbacks among moisture, hydrogen dynamics, and methanogen biomass. Moisture modulate hydrogen production, leakage, and methanogenic growth, shifting the system between a hydrogen-accumulating, methanogen-free regime and a syntrophic coexistence regime in which methanogens depress hydrogen below the threshold required for VFA oxidation to become exergonic. The resulting moisture-driven transition is a transcritical bifurcation governed by a moisture-dependent methanogen reproduction number, providing a compact link between hydrologic variability and the onset and collapse of syntrophy in soils.

  PublisherDOI

• An Integrated Modelling Framework to Determine Terrestrial Carbon Dioxide Removal via Enhanced Rock Weathering

  2026-03-14

  articleOpen accessCorresponding

  Enhanced rock weathering (ERW) is an emerging carbon dioxide removal (CDR) strategy that can support net-zero emission targets. However, current ERW modelling efforts rely on assumptions that introduce substantial variation in CDR estimates across varying ecosystems and hydroclimatic conditions. They typically ignore or oversimplify plant–soil interactions and high-frequency hydrological dynamics, obscuring short-term weathering responses and biotic feedbacks to soil moisture dynamics. Here, we introduce an integrated, process-based modelling framework, T&C-SMEW, which represents ecohydrological and ERW dynamics, along with microbially explicit biogeochemical processes. We compared framework simulations against a controlled mesocosm experiment and long-term field observations, demonstrating its ability to reproduce feedstock cation release, soil pH dynamics, gross primary production, and CO2 fluxes. T&C-SMEW reveals hydrological constraints and vegetation effects on ERW-mediated CDR by quantifying impacts on ecosystem respiration, net ecosystem exchange, and alkalinity export, emphasising the importance of ecohydrological modelling for ecosystem-level CDR estimation. These advances provide a modelling framework for identifying optimal deployment scenarios to establish ERW as a viable and operationally feasible CDR approach.

  PublisherDOI

• A soil structure-based modeling approach to soil heterotrophic respiration

  Biogeochemistry · 2025-03-13 · 1 citations

  articleOpen accessSenior author

  Abstract Soil microbial communities play a pivotal role in controlling soil carbon cycling and its climate feedback. Accurately predicting microbial respiration in soils has been challenged by the intricate resource heterogeneity of soil systems. This makes it difficult to formulate mathematical expressions for carbon fluxes at the soil bulk scale which are fundamental for soil carbon models. Recent advances in characterizing and modeling soil heterogeneity are promising. Yet they have been independent of soil structure characterizations, hence increasing the number of empirical parameters needed to model microbial processes. Soil structure, intended as the aggregate and pore size distributions, is, in fact, a key contributor to soil organization and heterogeneity and is related to the presence of microsites and associated environmental conditions in which microbial communities are active. In this study, we present a theoretical framework that accounts for the effects of microsites heterogeneity on microbial activity by explicitly linking heterogeneity to the distribution of aggregate sizes and their resources. From the soil aggregate size distribution, we derive a mathematical expression for heterotrophic respiration that accounts for soil biogeochemical heterogeneity through measurable biophysical parameters. The expression readily illustrates how various soil heterogeneity scenarios impact respiration rates. In particular, we compare heterogeneous with homogeneous scenarios for the same total carbon substrate and microbial biomass and identify the conditions under which respiration in heterogeneous soils (soils having non-uniform distribution of carbon substrate and microbial biomass carbon across different aggregate size classes) differs from homogeneous soils (soils having uniform distribution of carbon substrate and microbial biomass carbon across different aggregate size classes). The proposed framework may allow a simplified representation of dynamic microbial processes in soil carbon models across different land uses and land covers, key factors affecting soil structure.

  PublisherOA PDFDOI

• Preface to Ecohydrology of Inland and Coastal Waters in Honour of Ignacio Rodriguez‐Iturbe

  Ecohydrology · 2025-07-01

  article
  PublisherDOI

Recent grants

• MSA: Self-organizing principles for upscaling ecosystem water and heterotrophic carbon fluxes

  NSF · $200k · 2022–2026

Frequent coauthors

• Amilcare Porporato

  Princeton University

  57 shared

• Giuseppe Cipolla

  University of Palermo

  25 shared

• Leonardo Noto

  University of Palermo

  17 shared

• Matteo B. Bertagni

  Polytechnic University of Turin

  17 shared

• Rodolfo Souza

  15 shared

• Jun Yin

  South China Agricultural University

  8 shared

• Nandita Gaur

  University of Georgia

  6 shared

• Vinit Sehgal

  6 shared

Labs

• Calabrese, Salvatore - Department of Biological and Agricultural EngineeringPI

Education

• B.S., Civil and Environmental Engineering

  University of Palermo (Italy)

  2012

• M.S., Environmental Engineering

  University of Palermo (Italy)

  2014

• Ph.D., Civil and Environmental Engineering

  Princeton University (USA)

  2019

Awards & honors

• 2024 Vice Chancellor's Award in Excellence for Early Career…
• 2022 Embassy of Italy Award, ISSNAF Young Investigator Award…
• 2022 New Innovator in Food and Agriculture Research Award (F…