Assessment of organic carbon sequestration potential and mineralogy-driven leaching risks in biochar-amended soils under different cropping systems

Project Abstract

This study evaluates the dual facets of soil health and environmental risk by quantifying organic carbon sequestration potential and mineralogy-driven leaching risks in biochar-amended soils across diverse cropping systems. We integrated laboratory experiments, field trials, and modeling to determine how biochar characteristics (feedstock, pyrolysis temperature, and surface chemistry) interact with soil mineralogy, texture, pH, and moisture regimes to influence carbon stabilization mechanisms, sorption dynamics, and leachate composition. A multi-method approach included controlled microcosm experiments simulating rain events, a long-term field trial on representative agroecosystems, and advanced spectroscopic and microscopic techniques to characterize biochar-soil-mineral interactions at the micro-scale, coupled with stable isotope tracing to distinguish newly sequestered carbon from native stores. Our methodology quantified carbon input-output balances, identified key sorption sites (e.g., clays, oxides, and amorphous minerals), and assessed mineral-facilitated transport pathways for potential contaminants. Results indicate that biochar amendments can enhance soil carbon storage by promoting physical protection within soil aggregates and chemical stabilization through charge interactions with mineral surfaces, particularly in soils rich in iron and aluminum oxides. The degree of sequestration showed strong dependency on biochar physicochemical properties; high-temperature, aromatic-rich biochars exhibited greater persistence in weathered tropical and subtropical soils, whereas lower-temperature biochars provided rapid short-term gains in carbon stocks but were more susceptible to mineralized loss under intensive rainfall. Conversely, mineralogy-driven leaching risks varied with soil texture and mineral phase distribution. In clay-rich, highly weathered soils, biochar-coated mineral surfaces reduced the mobility of major cations but could mobilize certain trace elements under alkaline shifts, whereas sandy, porous soils exhibited enhanced percolation and potential leaching of dissolved organic carbon and micronutrients in the presence of labile biochar fractions. Cropping system management, including residue return, irrigation practices, and nutrient regimes, modulated both sequestration efficacy and leaching potential by altering soil moisture dynamics, soil respiration, and root exudation patterns that interact with biochar surfaces. The study developed risk-scoring models integrating biochar type, soil mineralogy, and agronomic practices to predict net soil carbon gain and leachate risk under climate variability scenarios. Sensitivity analyses highlighted the paramount importance of selecting biochar with appropriate surface functional groups and aligning amendment strategies with intrinsic soil mineralogy to maximize carbon sequestration while mitigating groundwater contamination risks. The findings provide actionable guidelines for optimizing biochar applications in agroecosystems to achieve sustainable carbon management, improved soil structure, and minimized leaching threats, informing policymakers, farmers, and land managers on best practices for climate-smart soil management.

Project Overview

What This Project Is About

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This project looks at how adding biochar to soils can help store more carbon and how the minerals in soil influence the movement of nutrients and potentially contaminants. It compares different cropping systems to see what works best for both climate and soil health.

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The Problem It Addresses

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Soils release greenhouse gases and lose nutrients over time. Biochar is a charcoal-like material added to soil to boost carbon storage and improve fertility, but its effects depend on soil minerals and management. This project investigates where carbon stays locked away and where mineral interactions could cause leaching, across farming systems.

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Objectives of the Project

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1. Explain how biochar changes soil carbon storage in different crops.
2. Describe how soil minerals interact with biochar to affect nutrient movement.
3. Compare leaching risks across cropping systems with biochar amendments.
4. Suggest practical guidelines for farmers to maximize benefits and minimize risks.

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What You Will Do Step by Step

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1. Review simple literature on biochar, soil minerals, and crop systems.
2. Set up a small experimental plan or data collection framework (field or soil lab data).
3. Measure basic soil properties (carbon content, pH, available nutrients) before and after biochar.
4. Analyze how different crops influence results and interpret mineral interactions.
5. Compare leaching indicators under each cropping system.
6. Summarize findings and draft practical recommendations.

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Expected Outcome

Clear understanding of where biochar improves carbon storage and where mineral-driven leaching may occur, plus actionable advice for selecting crops and biochar types to optimize soil health and environmental benefits.