Effects of biochar amendments on soil phosphorus transformation in agricultural soils

Biochar has attracted widespread attention due to its high carbon (C) content, abundant surface functional groups and porous structure. Numerous studies have shown that biochar has beneficial effects on the soil phosphorus (P) cycle. This article reviewed the current literatures on biochar and the effects of biochar amendments on the soil P cycle. The P biogeochemistry in biochar (e.g., total P content, P speciation, and P stability) that were prepared from several common feedstocks (e.g., animal manure, woody species, herbaceous species, sewage sludge) is highly variable and the pyrolysis-temperature dependent. Furthermore, the effects of biochar on the soil P availability, P speciation, characteristics of P loss in soils, changes in phosphatase activity, P uptake efficiency by plants, and soil P immobilization were discussed in detail. In summary, it is clear that soil P biogeochemical processes are largely influenced by biochar amendments in soils. The mechanisms and processes of P reaction dynamics in biochar amended soils should be further investigated to evaluate the potential sustainable use of biochar in agricultural soils.