Improving agricultural water use efficiency with biochar–A synthesis of biochar effects on water storage and fluxes across scales

B. M. C. Fischer*, S. Manzoni, L. Morillas, Monica Garcia, M. S. Johnson, S. W. Lyon

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    There is an urgent need to develop agricultural methods that balance water supply and demand while at the same time improve resilience to climate variability. A promising instrument to address this need is biochar – a charcoal made from pyrolyzed organic material. However, it is often unclear how, if at all, biochar improves soil water availability, plant water consumption rates and crop yields. To address this question, we synthesized literature-derived observational data and evaluated the effects of biochar on evapotranspiration using a minimal soil water balance model. Results from the model were interpreted in the Budyko framework to assess how climatic conditions mediate the impacts of biochar on water fluxes. Our analysis of literature-derived observational data showed that while biochar addition generally increases the soil water holding capacity, it can have variable impacts on soil water retention relative to control conditions. Our modelling demonstrated that biochar increases long-term evapotranspiration rates, and therefore plant water availability, by increasing soil water retention capacity – especially in water-limited regions. Biochar amendments generally increased crop yields (75% of the compiled studies) and, in several cases (35% of the compiled studies), biochar amendments simultaneously increased crop yield and water use efficiencies. Hence, while biochar amendments are promising, the potential for variable impact highlights the need for targeted research on how biochar affects the soil-plant-water cycle.
    Original languageEnglish
    JournalScience of the Total Environment
    Volume657
    Pages (from-to)853-862
    ISSN0048-9697
    DOIs
    Publication statusPublished - 2019

    Keywords

    • Biochar
    • Soil water retention curves
    • Soil water balance model
    • Budyko-framework
    • Water management
    • Soil-plant-water cycle

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