Concentrations and inter-element correlations of seven essential elements in wild plants of Japan

We assessed the effects of soil type on the concentrations of seven elements (calcium, potassium, sulfur, phosphorus, iron, manganese, zinc) in plants using x-ray fluorescence (XRF) analysis and plant specimens collected from calcareous and ultramafic soil areas, and ‘general soils’ (other types of soil represented by Brown Forest soils and Andosols) of Japan. Compared with the plants from other types of soils, the means of these seven elements were lower in plants originating from ultramafic soils, especially in phosphorus. Plants from calcareous soil areas had high iron and zinc concentrations on average, but this tendency was biased by plants collected on Mt. Fujiwara, which had extremely high average values of these elements. Calcium concentration in plants had a negative correlation with zinc or iron from calcareous or general soils, respectively, and iron showed positive correlations with zinc, manganese, and sulfur in plants from calcareous, ultramafic, and general soils, respectively. These correlations were not found in plants from general soils, suggesting that these relationships reflect the chemical characteristics of soil types. On the contrary, plants from all soil types showed a positive correlation between sulfur and phosphorus, whereas a positive correlation between potassium and phosphorus was found in plants from calcareous and general soils, but not in ultramafic plants, which instead showed a weak, but statistically significant correlation between potassium and sulfur. Statistically, iron and sulfur concentrations were positively correlated in all soil types, but manganese showed a low correlation with the other elements.