Different levels of nitrogen fertilizer were applied to maize and potato plants grown together. The study found that higher nitrogen levels increased the amount of beneficial bacteria and actinomycetes in the soil, but decreased harmful fungi. The diversity of the soil microbial community and the ability to use carbon sources also increased with nitrogen application. Maize plants had the highest microbial diversity with the highest nitrogen level, while potato plants did best with a slightly lower nitrogen level. Overall, nitrogen application can improve soil microbial communities and promote diversity in intercropped crops.