Strip-intercropping of eight crop species shows limited within-field variation of soil bacterial communities

The current crop system needs to become more sustainable to halt the severe environmental impacts associated with intensive monocultures. Alternative agricultural methods, like intercropping, could increase sustainability by better utilizing the biological functions of the plant-soil ecosystem, particularly through plant-associated bacteria. Soil bacteria are key players in supplying many ecosystem functions and thus contribute to plant performance. The effect of intercropping on soil bacteria is a crucial but understudied part of integrating intercropping into the global agricultural system. Here we characterized the effect of intercropping on soil bacterial communities, by comparing intra-versus interspecific crop interactions within one organic strip-intercropping field. We determined the alpha diversity and community composition of soil bacteria across 8 crop species and 16 crop combinations. We found that bacterial alpha diversity was not affected by crop species or crop combination. In contrast, bacterial community composition was influenced by crop species, with certain crops such as parsnip, potato and celeriac shaping their associated bacterial community in both intra- and interspecific crop interactions. Minute differences (<3 %) in soil moisture between crop species determined the strongest patterns observed here. Our findings highlight that crop diversification in the context of strip-intercropping does not always modulate soil bacterial communities under field conditions. • Bacterial communities were assessed across 8 crop species and 16 crop combinations. • Soil bacteria differed in community composition, but not in alpha diversity. • Intercropping with parsnip altered bacterial communities in oat, grass and celeriac. • Community variation was shaped mainly by crop-dependent soil moisture differences.