Influence of Ammonium Nitrogen Addition on N₂O Emissions from Different Tea Planting Age Garden Soil

A laboratory study was conducted to evaluate influence of soluble nitrogen addition on N₂O emissions from three soils of different tea planting age: high age（more than 50 years）, middle age（20 to 25 years）and low age（less than 8 years）．Four treatments were designed as follows: control（CK）, low nitrogen（LN）, medium nitrogen（MN）, high nitrogen（HN）．Results showed that N₂O emissions from high age tea planting garden were higher than middle age and low age tea planting garden due to higher pH and organic C content．Compared with the control, single nitrogen addition enhanced N₂O emissions from both soils, and N₂O emissions from middle age planting garden and low age planting garden soil had significant positively correlation with N fertilizer rate, while the maximum N₂O emissions were observed from MN treatment in high age tea planting garden soil．Application of exogenous ammonium nitrogen promoted decrease of soil pH, change quantity of pH from high age and middle age tea planting garden solis were in the order HN>MN>LN>CK , while from low age planting garden soil was in the order MN>HN>LN>CK．Application of exogenous ammonium nitrogen had a significant effect on soil acidification of tea plantations．Exogenous ammonium nitrogen significantly reduced soil pH and increased soil N₂O emissions．