“…Recent research results showed the potential for improving biochar P adsorption capacities by chemical modification [ 86 , 87 ], which includes its activation by different acids (HCI, HNO 3 , H 2 SO 4 , H 3 PO 4 and H 2 O 2 ), with different alkali (NaOH, KOH), with other oxidizing agents (KMnO 4 , Fe(III)) [ 85 ] and salts (MgCl 2 , CaCl 2 ) [ 82 , 87 , 88 ]. Although recent studies and review papers [ 75 , 89 ] describe biochar’s properties and its role in soil remediation, the efficacy of activated biochar on soil legacy P remediation requires further investigation due to diverse feedstock chemistry [ 69 ], activation technologies [ 90 , 91 ], and the complexity of biochar structural properties as well as soil properties [ 92 , 93 ].…”