Fig. 3

Pearson correlations between SO₄^2‒_LS and SO₄^2‒_CS (a), SO₄^2‒_LS+CS and the stable isotopes of δ¹³C-SOC (c), and SO₄^2‒_LS+CS and NO₃^-_LS+CS (j) in drying-affected soils studied, where the significance of the p-values for SO₄^2‒_LS+CS vs. NO₃^‒_LS+CS are at the level p < 0.001. The relationships between SO₄^2‒_LS+CS and soil relevant components in drying-affected soils studied showed that low levels of STS are associated with high levels of these components, and conversely, high levels of STS correspond to low levels of the relevant soil components. The relationships include SO₄^2‒_LS+CS with SOC (b), SIC (d), STN (e), STH (f), DOC_LS+CS (g), DIC_LS+CS (h), SiO₃^2-_LS+CS (i), NH₄ ⁺ _LS+CS (k), NO₂^-_LS+CS (l), DOP_LS+CS (m), and PO₄^3-_LS+CS (n).