Effects of soil and phylogeny on sulfur and phosphorus concentrations in wild plants on volcanic and non-volcanic soils in Japan

Andosols are soils characterized by relatively high sulfur concentrations, but also by their low phosphorus availability for crops and vegetables. We assessed the effect of soil type on the concentrations of sulfur and phosphorus in plants using handheld X-ray fluorescence (XRF) analysis on herbarium specimens collected from Andosols and non-volcanic soils in Japan. The sulfur concentrations in plants from Andosols were higher than plants from non-volcanic soils, but there was no significant difference between their foliar phosphorus concentrations. Only three specimens out of 1203 herbarium specimens were below the sulfur concentration (1000 mg kg⁻¹) needed for adequate growth of crops, but about half of specimens were below that for phosphorus (2000 mg kg⁻¹). The sulfur concentrations were high in herbaceous plants, especially in plants from the Brassicaceae and Liliaceae families. Overall, the results show that the sulfur concentrations in wild plants from Japan were higher in Andosols, with a low risk for sulfur deficiency. In contrast, the effect of soil type on the phosphorus concentrations in plants was small, and this may be explained because most wild plants grow under phosphorus-limiting conditions. Finally, the analysis reveals a strong correlation between sulfur and phosphorus concentrations in plants, suggesting the existence of a mechanism that controls the sulfur and phosphorus concentration ratios.