Element mg kg-1 Element mg kg-1 N 4520 B 95 P 3000 Zn 183 K 13,300 Cu 67 S - Mo 15 Ca 120000 Pb 72 Mg 7730 Ni 16 Si - Cr 75 Fe 6260 Co 14 Mn 2600 Cd 2

Table 2: Nutrient composition of paper and pulp ash, from Ref [38].