Evaluation of soil organic carbon sequestration potential under different land-use practices in degraded agroecosystems.

Project Abstract

Soil organic carbon (SOC) stocks and their dynamic responses to land-use practices are critical for sustaining soil health, productivity, and climate regulation in degraded agroecosystems. This study evaluates the sequestration potential of SOC under contrasting land-use strategies—conventional tillage with continuous cropping, no-tillage with crop diversification, agroforestry integration, cover cropping, and organic farming—across a gradient of degradation severity in a semi-arid agroecological zone. A multi-site field experiment combined with a robust soil physico-chemical and biological assessment framework was implemented over three full growing seasons, complemented by a paired watershed approach to capture hydrological and erosion feedbacks on SOC dynamics. Soil samples were collected at 0–20 cm, 20–40 cm, and 40–60 cm depths to quantify SOC concentration, bulk density, and texture; equivalent soil mass estimates were used to compare SOC stocks across treatments and depths. Stable isotope (13C/12C) probing and soil microbial biomass measurements were employed to elucidate the mechanisms of SOC stabilization, including particulate organic matter turnover, mineral-associated organic carbon formation, and priming effects driven by litter quality and root exudates. We integrated remote sensing-derived vegetation indices with in situ soil measurements to model SOC changes under temporal variations in biomass input and soil moisture regimes. A randomized complete block design with three replicates was used, and statistical analyses included mixed-effects models to account for spatial-temporal variability, along with structural equation modeling to identify direct and indirect drivers of SOC sequestration. Our results indicate that no-tillage with diverse crop rotations and leguminous cover crops substantially enhance SOC stocks in the topsoil (0–20 cm) by promoting continuous organic input and reducing mineralization losses; however, deeper SOC responds variably, depending on root depth distribution and soil structure. Agroforestry systems significantly increase SOC stocks at mid-depth (20–40 cm) through long-term carbon inputs from tree litter and root networks, while organic farming demonstrates moderate SOC gains associated with enhanced microbial activity and reduced chemical disturbances but may require longer timeframes to exceed conventional practices. Across sites, the magnitude of SOC sequestration potential correlated positively with baseline degradation status, soil texture (clay and silt fractions favoring mineral-associated SOC stabilization), and moisture availability that sustains microbial processes while minimizing decomposition losses. Sensitivity analyses reveal that improvements in soil porosity and aggregate stability amplify SOC stabilization by reducing wind and water erosion losses and fostering microhabitats for organo-mineral complexes. The study provides a comparative ranking of land-use practices for SOC gains under degraded conditions and yields actionable guidelines for policy and farm-level adoption, including recommended tillage reductions, integration of perennial and leguminous crops, targeted application of mulch and compost, and incorporation of agroforestry components to optimize SOC sequestration, soil fertility, and resilience to climate perturbations. The findings underscore the need for long-term monitoring to capture slow SOC processes and suggest that regional carbon accounting frameworks should incorporate depth-resolved SOC responses and management-specific stabilization pathways to accurately reflect the climate mitigation potential of degraded agroecosystems.

Project Overview

What This Project Is About

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A straightforward look at how different land-use choices affect the soil’s ability to store carbon, especially in areas where the soil has degraded. The project compares several land-use practices to see how each helps or hinders soil organic carbon (SOC) storage over time. It focuses on practical farming or land-management options that could improve soil health and climate benefits.

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The Problem It Addresses

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Soils in degraded landscapes often lose organic matter, reducing fertility, resilience, and carbon storage. Without clear evidence on which land-use practices best boost SOC, farmers and land managers may struggle to choose options that improve soil and climate outcomes. This project fills that gap by testing practical practices in real-world settings.

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Objectives of the Project

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1. Identify how different land-use practices impact soil organic carbon levels.
2. Measure changes in soil health indicators alongside carbon storage.
3. Compare short-term and medium-term effects of practices on SOC.
4. Provide practical recommendations for farmers and land managers.

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What You Will Do Step by Step

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1. Review existing literature on SOC and land use.
2. Select study sites representing degraded soils and multiple practices.
3. Collect soil samples at set depths and intervals.
4. Analyze samples for organic carbon and related soil health metrics.
5. Compare SOC across treatments using simple statistics.
6. Interpret results in terms of feasibility and impact.
7. Draft guidelines for implementation and monitoring.

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Expected Outcome

Clear evidence showing which land-use practices most effectively increase or preserve soil organic carbon in degraded soils, plus practical recommendations for adoption and monitoring to support soil health and climate benefits.