Abstract: In this study, we measured the in-situ N₂O emission rate in different types of tea gardens including productivity (high, medium and low) and planting years (10 a, 45 a and 100 a) and their adjacent forest, and analyzed the relationships between N₂O emission rate and soil properties including pH, organic carbon, total nitrogen, water-soluble organic carbon and nitrogen, microbial biomass carbon and nitrogen, ammonium nitrogen, and nitrate nitrogen. The results show that different types of tea gardens had significant effects on the changes of soil properties, and there were significant correlations between the soil properties. The average N₂O emission rate (N emission equivalents) in tea gardens was 3.14 mg·m^-2·h^-1, and the highest was in 100 a tea garden with the value of 4.47 mg·m^-2·h^-1. The N₂O emission rates in tea gardens were 3.1-7.2 times higher than that in forest. Mantel test shows that the N₂O emission rate was significantly and positively correlated with water-soluble organic carbon, organic carbon, total nitrogen, and microbial biomass carbon and nitrogen (P<0.05). Linear regression and structural equation models show that microbial biomass nitrogen (MBN) was the most significant factor affecting the N₂O emission rate in the tested fields.

Key words: tea garden, soils, N₂O, in-situ measurement, soil microbial biomass nitrogen