Extractable sulfate content in Japanese forest soils

The amounts of extractable sulfate in 12 forest soils were measured as a preliminary work to study sulfur dynamics in forest ecosystems. The sulfate content determined by the distillation method varied widely (10–880 × 10⁻⁶ gSg⁻¹) depending on the soil type and the depth. Japanese forest soils were broadly divided into two groups in sulfate level: one retains a large amount of sulfate and the other does not. In general, the surface soils to the depth of 10 cm contained small amounts of sulfate (< 100 × 10⁻⁶ gSg⁻¹), while subsoils contained more. The soil samples with low (< 4.6) or high (6 <) pH (H₂O) retained small amounts of sulfate. Black soils derived from volcanic ash retained great quantities of sulfate. The two levels of sulfate contents in Japanese forest soils suggests that the sulfur dynamics are different in these soils.