Fig. 2
From: Effect of biochar addition on legacy phosphorus availability in long-term cultivated arid soil
Effects of biochars derived from four different sources: sewage sludge (SSB), olive pomace (OPB), chicken manure (CMB), and date palm residues (DRB) averaged over the pyrolysis temperatures on soil inorganic (Pi) and organic P (Po)P fractions: A Resin-Pi, NaHCO3-Pi, and NaHCO3-Po); B NaOH-Pi and NaOH-Po; C HCl-Pi; D residual-P. For a P fraction, biochar feedstock sources sharing the same letter are considered not significantly different based on Student–Newman–Keuls (SNK) test at P < 0.05, LSD test (P < 0.05). LSD least significant difference value