Responses to N and P fertilization in a young Eucalyptus dunnii plantation: Microbial properties, enzyme activities and dissolved organic matter

The short-term effects of nitrogen (N) and phosphorus (P) fertilizer application on soil microbial properties, dissolved organic matter and enzyme activity were examined in a young Eucalyptus dunnii Maiden plantation at Huitong county, southern China. The objectives of the study were to understand how N and P addition impacts microbial activity and dissolved organic matter in subtropical plantation forest ecosystems. Treatments in this study included 100 kg N ha−1 (N1), 200 kg N ha−1 (N2), 75 kg P ha−1 (P1), 150 kg P ha−1 (P2) and the control without any fertilizer application (CK). N application significantly increased soil microbial biomass N, mineralized N, dissolved organic N, and invertase, urease and acid phosphatase activities, but decreased microbial biomass carbon (C) and P, basal respiration, metabolic quotient and dissolved organic P in comparison with the control. P application decreased microbial biomass N, mineralized N, urease and acid phosphatase activities, whereas it increased dissolved organic P, microbial biomass P and metabolic quotient. We conclude that the influences of N and P addition on microbial activity, soil enzyme activities and dissolved organic matter were different in the studied E. dunnii plantation.