Potato cultivar type affects the structure of ammonia oxidizer communities in field soil under potato beyond the rhizosphere

► We investigated AOA and AOB in two fields cropped with six different potato cultivars. ► The population sizes of AOA generally exceeded those of AOB. ► Abundances of AOB (but not AOA) generally increased in rhizosphere versus bulk soils. ► Soil type had a small effect on the community structure of AOB, but not on AOA. ► Cultivar type effects on AOA and AOB community structures go beyond the rhizosphere.