Collection and analysis of soil
Half a kilogram of soil was collected from each of five locations in Mecklenburg-Western Pommerania, Germany (see Figure 1). The soil types chosen (yard soil, two kinds of forest soil, swamp mud and beach sand) were based on locations where wild boar are commonly found. In addition, a bag of commercial potting soil was purchased to have a more controlled matrix with neutral pH, compared to the acidic forest soil samples collected (see Table S1 in the supplemental material), and sterile sea sand was obtained from a lab supplier (Carl Roth, Karlsruhe, Germany). The collected soils were analysed by an agricultural laboratory in Rostock, Germany (Landwirtschaftliche Untersuchungs- und Forschungsanstalt, LUFA) (see Table 2 in the supplemental material).