Developing more effective phosphorus-loaded iron modified biochar fertilisers for improvement of peanut yield and regulation of soil phosphorus fractions

Phosphorus-loaded iron-modified biochar (Fe-BP) can be used as farmlands' slow-release phosphorus (P) fertilizer. This study aimed to explore the effects of Fe-BP on soil P composition, phosphatase activity, peanut P accumulation, and P fertilizer utilization efficiency in sandy soi l . The two-year experiment was a randomized complete block design including no biochar and no P fertilizer (B0P0), no biochar and conventional phosphate fertilizer (CK) (B0P1, CK, P 2 O 5 is 144 kg· ha −1 ), biochar and CK (B1P1), iron-modified biochar (Fe-B) and CK (FeB-P1), P loaded Fe-B and CK (FeBP-P1), P loaded Fe-B and two third CK (FeBP-P2, P 2 O 5 is 96 kg· ha −1 ). It was found that Fe-B increased P accumulation, yield and P fertilizer utilization efficiency in peanuts. The physiological efficiency of P (PEP) of FeBP-P1 increased by 14.8 % compared with that of FeB-P1. During the fallow period, FeB-P1 decreased the soil available P content, while FeBP-P1 increased the soil available P content, and this effect lasted into the second year. Fe-B did not increase soil pH and did not significanlty affect acid phosphatase . FeBP-P2 increased NaHCO 3 -Pi by 66 % and 49 %, respectively, compared to B0P0 and B0P1. This increase is mainly due to the slow release of phosphates carried by FeBP-P2. Overall, Fe-BP enhanced soil available P under reduced P fertilizer application , improving P use efficiency. • Biochar does not increase soil pH after Fe modification. • Fe-B reduced soil available phosphorus, but Fe-BP does not. • FeBP-P2 increased the soil NaHCO 3 -Po, ensure peanut yield and improve the PUE.