Figure 2
Humic (top panels) and fulvic (bottom panels) acid concentrations in bulk soils under contrasting soil management regimes (left panel) and fertilizer treatments (right panel).
Error bars denote standard deviations (n = 3). Different small letters mean significant difference between treatments, at a given soil depth, at 0.05 (n = 3); no letters means no significant difference. Two-way ANOVA showed significant effects of soil management regime (P = 0.000) and soil depth (P = 0.000) and their interaction (P = 0.000) on humic acid content, and of fertilizer treatment (P = 0.000) and soil depth (P = 0.000) and their interaction (P = 0.000) on humic acid content. Two-way ANOVA showed significant effects of soil management regime (P = 0.001) and soil depth (P = 0.000) and their interaction (P = 0.004) on fulvic acid content, and significant effects of fertilizer treatment (P = 0.000) and soil depth (P = 0.001), but no marked interaction between them (P = 0.052), on fulvic acid content.
