Soil carbon sequestration exhibits differential mechanisms in two textured paddy soils under long-term green manuring

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S0167880926001295

Authors: Siwei Shi, Danna Chang, Guopeng Zhou, Songjuan Gao, Ting Liang, Jun Nie, Jing Huang, Weidong Cao

03 March 2026

https://doi.org/10.1016/j.agee.2026.110342

Highlights

•Green manuring can effectively enhance soil C sequestration and crop yield.

•Green manuring drives distinct C stabilization pathways in two textured soils.

•Green manuring shapes divergent DOC composition in different textured paddy soils.

Abstract

Green manure-rice rotation is an effective strategy for enhancing crop productivity and increasing soil organic carbon (SOC) stocks. However, the mechanisms driving SOC accumulation in functionally distinct fractions remain unclear. This study examined the response of particulate and mineral-associated organic carbon (POC and MAOC) to a green manure-rice-rice (GM) rotation in two long-term field experiments with contrasting clay contents (silty clay loam and silt loam). Compared to winter fallow (WF), GM increased rice yield on average by 11.7% with equivalent fertilizer input. Distinct pathways for soil carbon sequestration were identified in these two soils. In the silt loam soil, GM increased SOC by 10.6%, primarily through microbial necromass accumulation in the POC pool, while MAOC remained unchanged. In contrast, the silty clay loam soil saw a 17.1% increase in SOC, with microbial and plant-derived carbon contributing to both POC and MAOC pools. The increase in MAOC was closely associated with high clay content (i.e., abundant mineral-binding sites) and shifts in dissolved organic carbon (DOC) composition. Specifically, GM recruited specific fungal genera (e.g., Staphylotrichum) that decomposed lignin-like compounds, transforming them into aromatic and polycyclic aromatic compounds in the DOC pool, which then facilitated MAOC stabilization through direct sorption to mineral surfaces. Fourier transform infrared spectroscopy further indicated that GM increased carbohydrates in the MAOC of the silty clay loam soil, but remained unchanged in the silt loam soil. Overall, sustained green manure-rice rotation effectively enhances soil carbon sequestration through texture-specific pathways.

Source: ScienceDirect