Tile drainage is installed in agricultural fields to remove excess soil moisture to allow earlier planting of spring crops. Water moving from soil into tile drainage lines will potentially create a moist environment for earthworms. This study investigated how earthworms were distributed around tile lines, and how their abundance was affected by moisture in field crops on sandy and clayey soils. Earthworm abundance and soil moisture were similar above and between tile lines. Earthworm biomass was low in dry soils, peaked at 41 g moisture 100 g⁻¹, and declined in wetter soils, which affects the earthworm activity in agricultural fields.