Plant diversity significantly influences soil microbial communities and ecosystem processes, as shown by a long-term field experiment. The study manipulated plant diversity (1–16 species) in sandy soils with low organic matter and found that microbial community biomass, respiration, and fungal abundance increased with higher plant diversity. However, these changes were largely due to increased plant production rather than diversity itself. Despite this, plant diversity still affected N mineralization, a key process in N cycling. The positive relationship between plant diversity and productivity in N-limited soils was likely due to increased N availability, suggesting that plant-microbe interactions are crucial for ecosystem function. The study also found that microbial community composition changed with plant diversity, with a shift towards more fungi and fewer bacteria and actinomycetes. This shift was attributed to increased plant production rather than diversity. Microbial processes such as respiration and N mineralization were enhanced by plant diversity, but these effects were more strongly linked to plant production than to species richness. The results indicate that plant diversity enhances ecosystem function by modifying microbial communities, which in turn increases soil N availability and plant productivity. The study highlights the importance of plant-microbe interactions in linking plant diversity to ecosystem function. The findings suggest that in ecosystems with low organic matter, plant diversity has a significant impact on microbial communities and ecosystem processes. The results support the idea that plant diversity is an important factor in influencing ecosystem productivity through interactions with microbial communities.Plant diversity significantly influences soil microbial communities and ecosystem processes, as shown by a long-term field experiment. The study manipulated plant diversity (1–16 species) in sandy soils with low organic matter and found that microbial community biomass, respiration, and fungal abundance increased with higher plant diversity. However, these changes were largely due to increased plant production rather than diversity itself. Despite this, plant diversity still affected N mineralization, a key process in N cycling. The positive relationship between plant diversity and productivity in N-limited soils was likely due to increased N availability, suggesting that plant-microbe interactions are crucial for ecosystem function. The study also found that microbial community composition changed with plant diversity, with a shift towards more fungi and fewer bacteria and actinomycetes. This shift was attributed to increased plant production rather than diversity. Microbial processes such as respiration and N mineralization were enhanced by plant diversity, but these effects were more strongly linked to plant production than to species richness. The results indicate that plant diversity enhances ecosystem function by modifying microbial communities, which in turn increases soil N availability and plant productivity. The study highlights the importance of plant-microbe interactions in linking plant diversity to ecosystem function. The findings suggest that in ecosystems with low organic matter, plant diversity has a significant impact on microbial communities and ecosystem processes. The results support the idea that plant diversity is an important factor in influencing ecosystem productivity through interactions with microbial communities.