Fig. 4: Variations of Fe-OC and Ca-OC along the soil pH gradient. | Communications Earth & Environment

Fig. 4: Variations of Fe-OC and Ca-OC along the soil pH gradient.

From: Asymmetric responses of soil organic carbon stability to shifting dominance of pH-mediated metal-bound organic carbon

Fig. 4

a Linear relationship between metal-bound OC and soil pH. b Transitional patterns of Fe-OC% and Ca-OC% across different soil layers and pH intervals; c Relationship between the ratio of Ca-OC to Fe-OC and soil pH in different soil layers (fitted with an exponential function). Rectangles of different colors in b represent the average values of Fe-OC% or Ca-OC% in the respective soil layers and pH intervals, with whiskers indicating one standard deviation. Lowercase and uppercase letters show differences in Ca-OC% and Fe-OC% among different pH levels within the same soil layer at p < 0.05 (one-way ANOVA). Points of different colors in c denote various aridity sequences.

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