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

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