The iron, calcium, and magnesium content in kale and Chinese cabbage which plant in soil,hydroponics, and organic agriculture were determined by the techniques of atomic absorption spectroscopy (AAS) and UV-visible spectroscopy. These two methods showed the difference results. The AAS (standard addition method) was used to determine iron, calcium, and magnesium in plants. The results showed that the iron content in kale and Chinese cabbage were in range of 20.14 - 46.26 mg/kg and 22.92 - 50.46 mg/kg. While the calcium content in kale and Chinese cabbage were in range of 6592.97 - 13871.34 mg/kg and 6178.79 - 10591.53 mg/kg. For the magnesium content in kale and Chinese cabbage were in range of 2825.56 - 5989.06 mg/kg and 1895.73 - 6294.96 mg/kg, respectively.