Figure 2. Heat map illustrating the relative abundance of antibiotic resistance [erm(B), sul1, tet(B), tet(M) and tet(X)] and class 1 integron-integrase (intI1) genes in the soils by land use category. The color scale at the bottom indicates the gene abundance from no detection (white) to ≥ 10−4 gene copies/16S rRNA gene copies (dark blue). †Indicates cropland soils that have a history of receiving dairy manure, dairy wastewater, and/or biosolids. Detailed information about the sampling sites can be found in the Table S1 (Supporting Information).