Author ORCID Identifier

https://orcid.org/0009-0002-8313-8824

Date Available

1-1-2026

Year of Publication

2025

Document Type

Master's Thesis

Degree Name

Master of Agriculture (MAgr)

College

Agriculture, Food and Environment

Department/School/Program

Plant and Soil Sciences

Faculty

Hanna J. Poffenbarger

Faculty

Arthur Hunt

Abstract

Roots play a central role in soil organic matter (SOM) formation, yet the contributions of living roots compared with root- and shoot-derived litter remain incompletely understood across systems and management contexts. This thesis combines a global meta-analysis with a two-year field experiment to evaluate how continuous living root activity shapes soil organic carbon (SOC) dynamics. The meta-analysis synthesized 21 studies (57 observations) comparing cropping systems with enhanced living root continuity to systems with fallow periods or annual-only rotations. Perennial and continuous cropping systems increased annual C inputs and SOC stocks relative to controls, but their SOC sequestration efficiency declined because C inputs increased more than SOC storage.

Complementing the synthesis, a field experiment in a continuous maize system tested the separate contributions of rye cover crop living roots and litter under contrasting N levels. Rye living roots prevented substantial SOC losses observed in fallow plots and promoted early increases in mineral-associated organic matter compared to fallow, whereas litter return had no detectable effect. Nitrogen fertilization influenced particulate SOM but did not alter overall SOC responses. Living roots also shifted microbial community composition and modestly improved aggregation, indicating the early development of stabilization pathways.

Together, these results demonstrate that living root inputs are essential for maintaining and stabilizing SOM, while the influence of litter and short-term N additions is comparatively limited. Living roots thus represent a key mechanism through which agricultural systems sustain soil carbon and contribute to long-term soil health.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.602

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