Biochar’s efect on the ecosystem services provided by sandy-textured and contaminated sandy soils: a systematic review protocol

Abstract

Background: Biochar is a relatively new soil amendment method in agricultural practices that can improve the ecosystem services of soils. Biochar has commonly been applied to less fertile or contaminated soils, specifically sandy-textured and contaminated sandy soils, to improve their properties. However, the available literature indicates that not all sandy-textured and contaminated sandy soils show the same response to biochar applications, as the sign and size of the effect vary across studies. More specifically, primary studies show heterogeneous and potentially conflicting impacts of biochar application on a set of ecosystem services provided by these types of soils; namely, biomass production, water cycle, nutrient cycle, and climate regulation. Therefore, the objective of the present study is to systematically review the available evidence base to synthesise the impact and drivers of biochar amendments on four specific ecosystem services provided by sandy-textured and contaminated sandy soils. Methods: This review follows the guideline of the Collaboration for Environmental Evidence and corresponds to the ROSES (RepOrting standards for Systematic Evidence Synthesis) reporting standard. A comprehensive search strategy will be employed to cover peer-reviewed and gray literature through bibliographic databases, organizational and institutional websites, and web searches. Search terms and strategies have been developed to identify the impact of biochar on the ecosystem services of sandy-textured soils. The search results will be screened first by their title and abstract, and then by their full text. Two literature reviewers will do this based on eligibility criteria. A validity assessment will be conducted to critically appraise and assess the validity of studies using a common validity framework for environmental studies. Data will be extracted from the studies that are found to be valid for the review. Narrative synthesis and meta-analysis will be employed to synthesise the review results.