The integrated application of resistant crop varieties with biological control agents (BCAs) such as the Fusarium oxysporum [f.sp. strigae] strain ‘‘Foxy-2’’ has shown to be effective in fighting off the weed Striga hermonthica which is parasitic to several cereals cultivated in Sub-Saharan Africa (Schaub et al., 2006; Venne et al., 2009).\n ‘‘Foxy-2’’ proliferates in the rhizosphere and has been mainly studied for its virulence andmode of action. Contrary, no understanding is available regarding its interactions with key rhizosphere microorganisms steering relevant nutrient cycles in soils including nitrogen (N). In this study, we tested the hypothesis that ‘‘Foxy-2’’\n displaces indigenous prokaryotic,Ncycling communities in themaize rhizosphere due to competition for organic resources. Consequently, we evaluated if the application of an N-rich organic residue (i.e., Tithonia diversifolia with C/N ratio = 13, lignin content = 8.9%, polyphenol content = 1.7%) compensates these presumed competition\n effects. In a rhizobox experiment, quantitative polymerase chain reactionwas used to follow the response of rhizosphere\n ammonia-oxidizing archaea (AOA) and bacteria (AOB) as well as total bacteria and archaea following ‘‘Foxy-2’’ inoculation in two physico-chemically contrasting soils (sandy Ferric Alisol versus clayey Humic Nitisol).\n Soils were treated with or without ‘‘Foxy-2’’, S. hermonthica seeds, and T. diversifolia residues. Contrary to our expectations, we observed a distinct soil texture dependent, promoting effect of ‘‘Foxy-2’’ on rhizosphere prokaryotes. Abundance of AOA and total prokaryotic communities increased in response to ‘‘Foxy-2’’ in the sandy soil,while AOB remained unaffected. This effect on AOAwas acceleratedwhen T. diversifolia residueswere incorporated. Further, in the clayey soil, AOA abundance was promotedwhen exposed to S. hermonthica infestation of maize. This suggested their capability to adapt to this biotic stress situation. It was concluded that ‘‘Foxy-2’’ did\n not pose a negative effect on targeted indigenous microorganisms, but the underlying mechanisms for the observed promoting effect of AOA abundance by ‘‘Foxy-2’’ inoculation are yet to be understood.