fig2

Figure 2. Relationship of P added to a soil and soil-biochar mixtures (1%, 2% and 5% biochar additions) to a soil with greater P retention capacity (Apopka soil from Florida, USA) than the soil in Figure 1: (A) hardwood biochar, HWB; (B) poultry litter biochar, PLB and P remaining in solution after equilibration (Dari et al.^[55]). The x-axis has been expanded to show the relationship at low (environmentally relevant) P concentrations.