Modeling Calcite’s Sensitivity to Biogenic CO₂Production

A Pathway to Soil CO₂Efflux Partitioning

authored by

Kenneth Tetteh, Georg Guggenberger, Leopold Sauheitl, Kazem Zamanian

Abstract

Soil inorganic carbon (SIC), primarily calcite, represents a potentially reactive carbon reservoir, influencing soil–atmosphere CO₂exchange and acid–base buffering processes. Though often considered stable, SIC is sensitive to biogenic CO₂and acidification, risking extra CO₂emissions beyond soil organic matter (SOM) mineralization. This study investigates SIC reactivity using δ¹³C-enriched calcite (11.9 t ha^–1, +102.02‰) under organic residue decomposition, examining the effects of residue type (maize vs wheat), degradability (leaves vs roots), and placement (mixing vs mulching). Incubations at 25 °C with 80% soil–water saturation coupled high-resolution pH optodes and HYDRUS-PHREEQC simulations to quantify SIC reactivity. Mixed applications of labile maize leaves (C:N = 17.3) intensified topsoil (∼50% of the 10 cm column) acid loading (pH 7.9 → 5.7), promoting decarbonation and deepening acidification front (>3.2 cm). Soil respiration emerged as a key influencer of CO₂pressures, controlling porewater acid carrying capacity. Dissolution promoters (H₂O, H⁺, and H₂CO₃) drove topsoil decarbonation (0.84 t C ha^–1in mixed profiles vs 0.06 t C ha^–1in mulched) and subsoil (5–10 cm) bicarbonate accrual. δ¹³C tracing showed SIC-sourced CO₂peaks (+25 to +51‰, 40–60% contribution) during incubation’s first quarter (∼day 16–24) prior to SOM-domination (0 to −12‰, 20–10%), reflecting a mixed continuum of CO₂sources, SC turnover, and climate feedbacks.

Organisation(s)

Institute of Earth System Sciences

Type

Article

Journal

Environmental Science and Technology

Volume

59

Pages

23869-23882

No. of pages

14

ISSN

0013-936X

Publication date

11.11.2025

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

General Chemistry, Environmental Chemistry

Sustainable Development Goals

SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.1021/acs.est.5c07428 (Access: Open)