“…For the elemental composition: 0.007% of total nitrogen Nt, 0.201 ‰ of P2O5, 2.5% of total organic matter (Mot), 1.45% of total organic carbon (Cot), 0.357 ‰ of K2O,0.192 ‰ of Na2O,0.933‰ of Cao, and 0.391 ‰ of MgO. The contents of iron, manganese copper and zinc were, respectively, 0.4, 7.4, 0.9, 2.6 ppm [8][9][10][11].…”