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Tree nutrient concentrations, root biomass, soil nitrogen (N) and phosphorus (P) contents, and enzyme activities were determined in a radiata pine plantation (Pinus radiata D. Don) on a sandy loam soil receiving 19 years of repeated biosolids applications, and the composition of soil microbial groups was assessed using phospholipid fatty acid analysis. Biosolids application significantly increased soil organic N, available P and foliar N concentration, but had no significant impact on foliar P concentration over the long term. Biosolids application improved aboveground tree growth but reduced fine-root biomass. Repeated biosolids applications also altered the composition of soil microbial community and increased the potential activities of N-acetyl-β-glucosaminidase and acid phosphomonoesterase. Changes in soil N and P availability were better explained by variations in the composition of bacterial …