Biochar application to soils can regulate soil phosphorus availability: a review

Abstract

Abstract Phosphorus (P) is essential for basic natural processes and can limit the productivity of entire ecosystems. However, agricultural lands worldwide currently suffer from P deficiency. The application of P fertilizers is not only poorly utilized, but also results in the gradual accumulation of P. Biochar, a substance produced by the pyrolysis of biomass under low oxygen levels, is frequently used as a soil amendment. It provides P in a form that is readily available for plant uptake, and thus addresses both short- and long-term soil P deficiencies. In this paper, we systematically reviewed relevant studies on “biochar and soil” or “biochar and soil P” published in the past decade (2013–2023). A synthesis of the reported results revealed that analyzing the effect of biochar on soil P through changes in soil physicochemical properties and microbial communities has gradually emerged as a prominent area of research in recent years. The purpose of this study was to analyze the differential effects of biochar addition on soil P availability, including the clarification of the underlying mechanisms. The results showed that although biochar application generally exerts a positive effect on soil P availability, there are differences in the extent of effects based on application conditions. Shifting to mechanisms, biochar application not only directly increases the available phosphorus (AP) content of soil, but also indirectly influences soil P availability via changes in soil physical, chemical, and biological properties. To summarize, biochar application can affect soil P availability to different degrees through direct or indirect pathways. Graphical Abstract

Keywords

• Biochar
• Soil available phosphorus
• Adsorption and desorption
• Nutrient cycling
• Mechanism analysis