Assessing the impact of agroforestry integration on soil carbon sequestration and crop yield under varying climate scenarios in smallholder farms.

Project Abstract

This study examines how integrating agroforestry systems within smallholder farms influences soil carbon sequestration and crop yield across a range of climate scenarios, combining field experiments, farmer surveys, and modeling approaches to generate scalable insights for climate-smart management. The research employs a randomized, split-plot design across three representative agroecological zones with distinct rainfall patterns and soil types to compare traditional monoculture controls against multi-strata agroforestry configurations that include timber, nitrogen-fixing legumes, and shade-tolerant understory crops. Over a three-year period, soil carbon stocks are measured at 0–15 cm and 15–30 cm depths using dry combustion methods, with soil organic carbon fractions quantified to discern priming effects and stabilization mechanisms. Concurrently, aboveground and belowground biomass production, leaf litter turnover, and root exudates are monitored to elucidate carbon inputs and turnover rates. Crop yield data for primary staples and intercrops are collected seasonally, alongside phenological observations and microclimate metrics such as light interception, soil moisture, and soil temperature. The study integrates stable isotope tracing (13C/15N) to partition carbon and nitrogen fluxes among tree components, crops, and soil pools, enabling a nuanced understanding of the pathways through which agroforestry modulates soil carbon dynamics and nutrient cycling under different climate perturbations, including shifts in temperature, precipitation intensity, and drought frequency. A climate–soil–crop model is parameterized with local measurements and literature-derived relationships to project long-term outcomes (10–20 years) under three climate scenarios baseline, moderate warming with altered precipitation, and severe drought with higher evapotranspiration. Sensitivity analyses identify key drivers of soil carbon sequestration and yield resilience, such as tree density, species selection, rooting depth, litter quality, and fertilizer regimes. The results are expected to demonstrate that agroforestry enhances soil carbon stocks through increased litter input, improved soil structure, and microclimate regulation, while maintaining or improving crop yields via legume nitrogen fixation, moderated evapotranspiration, and diversified risk. The study also investigates trade-offs between biomass accumulation and annual crop productivity, offering thresholds for optimal agroforestry designs that balance carbon sequestration with farmer profitability. Stakeholder engagement includes participatory farm trials, focus group discussions, and cost-benefit analyses to assess adoption viability, economic returns, and policy implications. The findings will inform guidelines for implementing climate-smart agroforestry in smallholder contexts, including recommended species mixtures, planting densities, maintenance practices, and monitoring protocols to optimize soil carbon sequestration trajectories and stabilize or enhance crop yields under evolving climatic conditions. By integrating empirical data with scenario-based projections, the research contributes to scalable, evidence-based strategies for mitigating climate change impacts while sustaining agricultural productivity and soil health in rural landscapes.

Project Overview

What This Project Is About

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A plain-language overview of how integrating trees with crops can influence soil health, carbon storage, and crop yields, especially under different weather patterns encountered by small farms. The project compares farms using agroforestry with those that do not, to see how these systems affect soil carbon and crop output over several seasons.

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The Problem It Addresses

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Smallholder farms often rely on a single crop and face climate variability that can reduce yields and degrade soil. Agroforestry may build soil carbon and stabilize rainfall, but evidence from real farm settings under different climates is limited. This project investigates whether mixing trees with crops can improve soil health and yields consistently, helping farmers adapt to climate change.

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Objectives of the Project

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1. Assess how agroforestry changes soil carbon levels over time.
2. Compare crop yields between agroforestry farms and conventional farms under varying climate conditions.
3. Identify which tree species combinations best support soil and yield outcomes.
4. Provide practical guidelines for farmers on designing agroforestry systems.

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What You Will Do Step by Step

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1. Review existing research and select study sites representing different climate scenarios.
2. Collect soil samples and measure carbon content at multiple times each year.
3. Record crop yields and growing conditions (rainfall, temperature, pest pressures).
4. Compare results between agroforestry and non-agroforestry plots using simple statistics.
5. Identify patterns and draft practical recommendations for farmers.

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Expected Outcome

A clear assessment of whether agroforestry improves soil carbon and yields across climates, along with simple, actionable steps for farmers to adopt agroforestry practices. The project should provide evidence to support or refine farmer decision-making in different weather conditions.