Abstract
Biochar is a widely known soil amendment. Here we synthesize the available information on influence of biochar application on different soil properties and crop productivity using meta-analysis. Global data on influence of biochar applications on different soil physical, chemical, microbial properties, and crop productivity were extracted from literature and statistically analyzed. Based on selection criteria, 59 studies from the literature published between 2012 and 2021 were selected for the meta-analysis. Correlations were developed between effect size of biochar application on different soil properties and crop productivity. Application of biochar increased soil pH, cation exchange capacity, and organic carbon by 46%, 20%, and 27%, respectively, with greater effects in coarse and fine-textured soils. Effects on chemical properties were variable among biochar prepared from different feedstocks. Among physical properties, biochar application reduced bulk densities by 29% and increased porosity by 59%. Biochar prepared at higher pyrolytic temperatures (> 500 ℃) improved bulk density and porosity to greater extents (31% and 66%, respectively). Biochar prepared at lower pyrolytic temperatures (< 500 ℃) had a greater effect on microbial diversity (both bacterial and fungal), with more diverse bacterial populations in medium and coarse textured soils, while fungal diversity increased in fine textured soils. Biochar applications increased crop productivity only in fine and coarse textured soil. The effect size of biochar application on crop productivity was correlated with responses to physical properties of soils. The meta-analysis highlighted the need to conduct long-term field experiments to provide better explanations for changes in biochar properties as it undergoes aging, its longer-term effects on soil properties, and timing of re-application of different biochars.
Highlights
Agricultural productivity is continually limited by progressive declines in soil condition and poor nutrient use efficiencies, resulting in food insecurity (Jones et al 2013)
The increase in soil pH in coarse-textured soils was significantly (P < 0.05) greater than in fine-textured soils. Biochars prepared at both high and low pyrolytic temperatures resulted in a significant (P < 0.05) increase in soil pH compared to the control
This meta-analysis of the available literature assessed the current state of knowledge on how biochar applications can affect soil physical and chemical properties, microbial diversity, and crop production
Summary
Agricultural productivity is continually limited by progressive declines in soil condition and poor nutrient use efficiencies, resulting in food insecurity (Jones et al 2013). Problems such as climate change, increasing growth of the human population, and urbanization place increased pressure on agricultural systems, which aggravates these problems (Lal 2009). (2022) 4:8 agroecosystems need to be reconsidered, to resolve the wide array of problems affecting agricultural production, including disconnects in nutrient supply, demand, and recycling, and water use (Lal 2013). One potential solution could be recycling organic nutrients back to soil, to help sustain soil organic matter, which typically results in improvements in soil physical and chemical properties (Girmay et al 2008). The selection of organic material to apply is critical, since some sources may have negative effects on soils, depending upon the quality of organic material or the presence of contaminants (Jones and Healey 2010)
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