Cerium-modified biochar: A recycling biomaterial for regulating phosphorus availability in paddy ecosystem from coastal mudflat reclamation

Abstract Phosphorus (P) is a vital element for plant growth, especially in mudflat-reclaimed soil due to its extra alleviation of adverse effect by salt stress. P availability in mudflat-reclaimed soil is a critical factor for crop yield. In this study, cerium-modified straw biochar (Ce-MSB) derived from maize straw was prepared and characterized and its influence on P availability of the paddy soil was evaluated. The results indicated that the cerium elements were chemically bound to the functional groups of the biochar surface through SEM, EDX and FTIR techniques. The equilibrium process of P by Ce-MSB was described well by the Langmuir isotherm model ( R 2  > 0.99). The maximal P adsorption capacity of Ce-MSB was influenced remarkably by temperature. Accordingly, the addition of Ce-MSB significantly decreased the P content of surface water in paddy system after 3 months, while increasing the soil P availability. Furthermore, the incorporation of both common biochar and Ce-MSB into the soil increased the SOM content, while decreased soil pH and EC. Biolog EcoPlateTM trials indicated that Ce-MSB has no significantly negative effects on soil microbial diversity. This study provides valuable information for the source-reduction of P discharge from paddy system and improvement of P availability. Phosphorus (P) is a vital element for plant growth, especially in coastal reclaimed mudflat due to its extra alleviation of adverse effect by salt stress. P availability in mudflat-reclaimed soil is a critical factor for crop yield. In this study, cerium-modified straw biochar (Ce-MSB) derived from maize straw was prepared and characterized and its influence on P availability of the paddy soil was evaluated. The results indicated that the cerium elements were chemically bound to the functional groups of the biochar surface through scanning electron microscopy (SEM), energy dispersive X-ray spectrum scanning (EDX), and fourier transform infrared spectroscopy (FTIR) techniques. The equilibrium process of P (PO 4 3− ) by Ce-MSB was described well by the Langmuir isotherm model ( R 2  > 0.99). The maximal P adsorption capacity of Ce-MSB was influenced remarkably by temperature, which was 58, 69, and 78 mg g −1 under 5, 25, and 40 °C, respectively. Under laboratory simulation, the addition of Ce-MSB significantly decreased the P content of surface water in paddy system after 3 months, while increasing the P availability of soil. Furthermore, the incorporation of both common biochar and Ce-MSB into the soil increased the SOM content, while decreased soil pH and EC. Biolog EcoPlateTM trials indicated that Ce-MSB has no significantly negative effects on soil microbial diversity. This study provides valuable information for the source-reduction of P discharge from paddy system and improvement of P availability.