Biochar's cost constraints are overcome in small-scale farming on tropical soils in lower-income countries

摘要

Biochar has been lauded for its potential to mitigate climate change, increase crop yields, and reverse land degradation in tropical agricultural systems. Despite its benefits, confusion persists about whether the use of biochar is financially feasible as a soil ameliorant. A comprehensive review of previous studies of biochar's financial feasibility was performed (33 relevant publications). Financial performance appraisal (US$ Mg-1 biochar) and greenhouse gas abatement cost estimates (US$ Mg-1 CO(2)e) were used to gauge the financial feasibility of the biochar scenarios within each publication. Ordinary least squares multiple linear regression was used to evaluate the predictive capacity of scenario financial feasibility as dependent on variables including national income levels, climatic conditions, pyrolysis technology scales, and pyrolysis capabilities. Analysis revealed that scenarios where biochar was applied targeting yield increases in high-value crops in tropical locations with low incomes and biochar-focused small-scale production, were overall significant predictors of biochar scenario financial feasibility. We find that the average abatement cost of biochar applied in 'lower-income countries' is -US$58 Mg-1 CO(2)e (financially feasible) compared with +US$93 Mg-1 CO(2)e in 'higher-income countries' (not financially feasible). Climate policies of lower-income countries in tropical climates should consider biochar as an input for small-scale climate smart agriculture to address land degradation in tropical agricultural systems. Based on recent evidence it is suggested that biochar fertilizers, a value-added biochar product, could present a commercially feasible pathway for biochar value-chain development in higher-income countries.