The effect of biochar on crop productivity and soil salinity and its dependence on experimental conditions in salt-affected soils: a meta-analysis

Abstract

Abstract Biochar can significantly alter soil properties and therefore can play an important role in increasing the resilience of agricultural systems to salt conditions. To match biochar to salt-affected soil constraints and application needs, a thorough understanding of the impact of biochar, soil properties and experimental conditions on crop productivity and soil salinity is necessary. This meta-analysis (MA) of the available literature for the first time quantitatively assessed the effect of not only biochar applied to salt-affected soils but also that of different salt-affected soil properties on crop productivity and soil salinity. The results showed that biochar was most effective at improving crop productivity in salt-affected soils, with an application rate ranging from 40–50 t/ha, a C/N ratio ranging from 40–60, a pyrolysis temperature ranging from 450–550 °C and a pH ranging from 7–8. Biochar with an EC of < 2 mS/cm, an application rate of 20–30 t/ha, a C/N ratio of > 80 t/ha or a pyrolysis temperature of < 450 °C reduced the soil salinity. Regardless of climatic and soil conditions, biochar applied to salt-affected soils increased crop productivity under different climatic conditions. Biochar increased soil salinity under different temperature and soil pH conditions and decreased soil salinity in salt-affected soils treated with all types of salts. Biochar was most effective at improving crop productivity and soil salinity in sulfate-dominated saline soils. Regardless of the planting and management practices, biochar increased crop productivity in salt-affected soils. The combined application of biochar and inorganic fertilizer significantly increased crop productivity and kept soil salinity unchanged. This meta-analysis provides the first quantitative review of the effect of biochar on crop productivity and soil salinity in salt-affected soils, which is critical for developing engineered biochar to restore salt-affected soils and promote food security. Graphical Abstract

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