Constrained ordination diagram for sample plots in the first two redundancy analysis (RDA) axes.

<p>The axes were based on the soil chemical factors and their relationship with the relative abundance of <i>Acidobacteria</i> at the phylum and class (subgroup) levels (a), <i>Actinobacteria</i> at the phylum and order levels (b), and <i>Verrucomicrobia</i> at the phylum and class levels (c). Squares represent soils with a straw blanket, and circles represent uncovered soils. N-amended soils are represented in blue. N+V-amended soils are represented in red. Soils excluding any N and V fertilizer are represented in green.