Page 5 - Read online

Original Article | Open Access

Carbon Footprints

Maffia et al. Carbon Footprints 2026, 5, 7 DOI:10.20517/cf.2025.91

Sustainable fertilizers from wastes: a strategy to
enhance soil carbon, improve soil quality, and
mitigate emissions

Angela Maffia, Federica Marra, Santo Battaglia, Carmelo Mallamaci, Adele Muscolo

Keywords:
Compost, digestate, life
cycle assessment, microbial
community, organic
amendments, soil carbon
sequestration,
sulfur-bentonite,
vermicompost

Citation: Maffia, A.;
Marra, F.; Battaglia, S.;
Mallamaci, C.; Muscolo, A.
Sustainable fertilizers from
wastes: a strategy to
enhance soil carbon,
improve soil quality, and
mitigate emissions. Carbon
Footprints 2026, 5, 7.
https://dx.doi.org/10.20517
/cf.2025.91 Abstract
The transition to sustainable fertilization strategies is essential to reconcile agricultural
Received: 5 Oct 2025 productivity with soil health and climate change mitigation. This study assessed the
First Decision: 20 Nov agronomic and environmental performance of four waste-derived fertilizers - compost (C),
2025
Revised: 12 Dec 2025 vermicompost (V), olive-based digestate (D), and sulfur bentonite with olive pomace
Accepted: 19 Dec 2025 (SBO) - through integrated soil analyses and life cycle assessment (LCA). The results
Published: 29 Jan 2026 showed that compost and vermicompost exhibited the highest degree of organic matter
humification, improving total organic carbon, cation exchange capacity, soil microbial
Academic Editor:
Dafeng Hui biomass carbon, and enzymatic activity. Vermicompost provided the greatest increase in
Copy Editor: humification rate and bacterial biomass, while compost maximized fungal-to-bacterial
Ping Zhang ratios, soil enzymatic activities, and stable carbon pools. Digestate enhanced soil organic
Production Editor: carbon and fungal biomass, although with lower humification indices and higher
Ping Zhang
water-soluble phenols. SBO strongly acidified the soil and shifted microbial communities
toward fungal dominance but contributed the highest greenhouse gas emissions due to
sulfur processing. LCA confirmed vermicompost as the most climate-friendly amendment
(25 kg CO 2 eq ton ), followed by compost (43), digestate (110), and SBO (167). These
-1
findings indicate that waste-derived organic fertilizers can simultaneously improve soil
quality, promote carbon sequestration, and reduce emissions compared with synthetic
inputs, with vermicompost and compost offering the greatest agronomic and

Agriculture Department, Mediterranea University, Reggio Calabria 89124, Italy.

Correspondence to: Prof. Adele Muscolo, Agriculture Department, Mediterranea University, Reggio Calabria 89124, Italy. E-mail:
amuscolo@unirc.it

www.oaepublish.com Submit a Manuscript: https://ucenter.oaepublish.com