A two‐step digestion procedure using HNO3and H2O2/UV irradiation is described. The samples are predigested with HNO3, succeeded by digestion in H2O2under UV irradiation. The maximum temperature is 150°C. The digestion is performed without sample transfer during oxidation. The analytical data obtained by the new digestion method do not deviate from those obtained by HClO4digestion. The macronutrient elements including P were measured.