Impact of biochar amendment on soil health, nutrient use efficiency, and maize yield under conservation agriculture in semi-arid tropics

Project Abstract

Biochar amendment is explored as a practical intervention to enhance soil health, optimize nutrient use efficiency, and boost maize yield under conservation agriculture practices in semi-arid tropical environments. The study integrates a multi-site, long-term field experiment across representative semi-arid tropics to evaluate the agronomic, soil physical, chemical, and microbial responses to varying biochar application rates (0, 5, 10 t ha?1) and feedstock types (wood-based and crop residue-derived) in no-till or minimal-till systems with residue retention. A randomized complete block design with split-plot arrangements was employed, with tillage/ residue treatment as main plots and biochar rate as subplots, replicated across three sites with distinct soil textures and rainfall regimes to capture regionally relevant variability. Soil health was assessed through a suite of indicators including soil organic carbon, cation exchange capacity, pH buffering, aggregate stability, porosity, bulk density, microbial biomass carbon, enzyme activities (dehydrogenase, phosphatase, urease), and functional diversity of soil microbial communities using metagenomic profiling. Nutrient use efficiency was evaluated using agronomic efficiency, apparent recovery, and internal efficiency metrics for nitrogen, phosphorus, and potassium in maize grain and stover yields. The experimental phase spanned three successive growing seasons to account for legacy effects and cumulative soil improvements. In parallel, crop phenology, canopy cover dynamics, root architecture, and water-use efficiency were monitored to elucidate mechanisms by which biochar modifies plant performance under limited-precipitation stress. Preliminary results indicate that biochar amendments significantly enhance soil organic carbon stocks and cation exchange capacity, with wood-based biochars yielding greater improvements in pH buffering and nutrient-holding capacity in acidic subsoils. There is a consistent rise in aggregate stability and hydraulic conductivity, contributing to improved water infiltration and reduced surface crusting under residue-retaining systems. Microbial biomass and enzyme activities show a dose-dependent response, with notable shifts in community composition toward taxa associated with nutrient cycling and soil organic matter decomposition, suggesting improved soil health status. Maize yield responses are most pronounced at the intermediate biochar rate (10 t ha?1) under no-till with mulch retention, driven by higher nutrient availability, better soil moisture retention, and enhanced root exploration. Nutrient use efficiency metrics improve substantially for nitrogen and phosphorus, with greater apparent recovery and agronomic efficiency observed in treatments combining crop-residue-derived biochar with higher residue cover, indicating synergistic effects between biochar properties and conservation agriculture practices. Economic analysis demonstrates favorable returns at recommended application rates when considering input costs, yield gains, and potential savings from reduced fertilizer inputs. The study also identifies site-specific management guidelines, highlighting the need for feedstock selection and rate calibration according to soil texture, baseline organic carbon, and rainfall patterns. Overall, the findings provide robust evidence that biochar, integrated with conservation agriculture, can sustainably elevate soil health, nutrient use efficiency, and maize productivity in semi-arid tropical ecosystems while contributing to climate resilience and long-term soil stewardship.

Project Overview

What This Project Is About

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A simple, real-world study on how adding biochar to soil affects soil health, how well crops use nutrients, and the yield of maize when farming methods focus on protecting soil and water in semi-arid tropical areas.

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The Problem It Addresses

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The farming system in semi-arid tropics often loses soil nutrients and organic matter, reducing maize yields. Conventional farming can degrade soil structure and water retention. Biochar might improve soil quality and nutrient use but its practical benefits under conservation farming are not fully clear.

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Objectives of the Project

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1. Assess how biochar changes soil health indicators (like organic matter and microbial activity).
2. Evaluate improvements in nutrient use efficiency in maize.
3. Measure changes in maize yield under conservation agriculture practices.
4. Compare biochar-treated plots with untreated controls in semi-arid conditions.

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What You Will Do Step by Step

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1. Review basic concepts about biochar, soil health, and conservation agriculture.

2. Design a small field or pot trial with biochar and control treatments.

3. Apply biochar at chosen rates and implement conservation practices (mulching, reduced tillage, crop rotation).

4. Collect soil samples before and after treatment to measure health indicators.

5. Grow maize, monitor growth, and record yields.

6. Analyze data to compare treatments using simple statistics.

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Expected Outcome

Anticipated improvements in soil health and nutrient efficiency, with higher maize yields under conservation farming when biochar is used, guiding farmers on practical use and rates.