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Table 1 Total and water-soluble (W) Fe  % and P (P2O5) %, in the Fe- and P-sources used in the manufacture of NPK compound fertilizer

From: Incorporation of humic-derived active molecules into compound NPK granulated fertilizers: main technical difficulties and potential solutions

Products Total Fe % W-Fe % Total P %a W-P %a
Fe products
 FeHEDTA 13.0 13.0
 FeDTPA 11.9 11.9
 FeEDTA 14.1 14.1
 FeSO4 20.1 20.1
 Fe2O3 69.9 0
P products
 DAP 0.182 0.022 46.5 43.8
 TSP 0.175 0.025 46.4 39.1
  1. Fe in DAP and TSP results from its presence in the raw materials used to DAP and TSP manufacture process (mainly, in phosphoric acid and rock phosphate)
  2. aP is expressed as P2O5