Quantify sustainability benefits of diversified cropping systems.

Promoting soil organic carbon (SOC) accumulation in croplands is an overarching goal of agricultural sustainability, but predicting SOC gains in diversified cropping systems remains elusive and context dependent. To tackle this issue, we have undertaken a research initiative that integrated comprehensive measurements of carbon dynamics and stable carbon isotopes from long-term agricultural field experiments with calibration and validation of carbon isotope-enabled mechanistic models. This project enabled improved quantification and prediction of the impacts of diversified cropping systems on SOC storage and related soil health metrics, ultimately informing agricultural policy and market-based sustainability incentives.

Resolve mechanisms controlling SOC stabilization

A comprehensive understanding of the mechanisms responsible for SOC stabilization is the prerequisite for programming the land-based mitigation actions and modeling carbon cycling in support of carbon mitigation. Through field measurements, lab incubation and microbial models, we have uncovered underappreciated geochemical processes controlling C stabilization and emission (as CO₂ and CH₄) in both forest and agricultural soils (Huang and Hall, Nature Communications, 2017), and proposed a new conceptual view of decomposition responses to temporal variations in O₂ availability to inform theory and mechanistic model development (Huang et al., Global Change Biology, 2020 and 2021). Our research findings have significant implications for guiding effective ecosystem conservation practices and promoting long-term ecosystem sustainability.

Reconcile classical and modern views of SOC persistence at both site and continental scales.

Modern perspective on SOC persistence proposes that lignin is a minor constituent of SOC, challenging the older view that lignin contributes substantially to SOC persistence. To examine these competing viewpoints regarding lignin’s role in SOC persistence, we integrated lab and field incubations and employed data-model fusion that used a newly developed model (Liao, Huang et al., Soil Biology and Biochemistry, 2022) and a modified mechanistic C model (Yi, Huang et al., Global Change Biology, 2023) at both site and continental scales. This work revealed the variable contributions of lignin to SOC among soils as a function of their biogeochemical characteristics, reconciling some aspects of classic and modern views of SOC persistence (Huang et al., Nature Communications, 2023). These insights have significant implications for refining Earth-system models and improving our ability to predict soil carbon cycling in response to environmental changes.