Emissions Of Greenhouse Gases Under Different Planting Ages Of Tea Soils

Greenhouse Gases (GHGs) emissions from agroecosystem had attracted more attention nowadays, and tea plantation is one of major land use in south China. To understand the current emission situation and its impact mechanism of GHGs from tea plantation ecosystem and provide the basis for the scientific production of tea plantation, Nitrous, Carbon dioxide and Methane oxide fluxes and their influence factors were studied by closed chamber-Gas Chromatography method through field testing and laboratory analysis under different planting ages of tea soils at Xianning, Hubei. The results were as follows:1) Soil N2O flux ranged from -31.13to554.46μg/(m2·-h) under different planting ages of tea soils, with the mean flux from1.57to64.78μg/(m2·-h). The order of average soil N2O flux was:5years tea plantation>40years tea plantation>15years tea plantation> woodland. Soil N2O flux from different planting ages of tea soils showed a seasonal variation, with the highest in spring. Soil moisture and soil N2O of40years tea plantation had a significant linear correlation; soil NH4+content and soil N2O of5years tea plantation had a highly significant correlation; and there were correlations between soil N2O flux and soil NO3-、DOC、MBC content of5and40years tea plantation.2) Soil CO2flux ranged from24.54to210.29mg/(m2·h), with the mean flux from85.17to93.79μg/(m2·h). The order of soil CO2flux was:5years tea plantation>40years tea plantation> woodland>15years tea plantation. Soil CO2flux showed a seasonal variation, with the highest in summer. Soil CO2flux was highly correlated with temperature in5cm soil depth and there were no significant correlations between soil CO2fluxes and soil moisture. Soil MBC content and soil CO2of40years tea plantation had a significant linear correlation.3) Soil CH4flux ranged from-50.72to73.46μg/(m2·h), with the mean flux from-4.22to3.09μg/(m2·h). The order of soil CH4flux was:40years tea plantation>15years tea plantation>5years tea plantation> woodland. Soil CH4flux showed a seasonal variation, with the highest in winter. Soil CH4flux of5years and15years were negative. Soil CH4flux was correlated with temperature in5cm soil depth in40years tea plantation.4) During the incubation, after adding nitrogen, N2O cumulative emissions were5.68、1.45、5.14mg/kg; CO2cumulative emissions were125.52、251.88、177.6mg/kg; CH4cumulative emissions were-1.94、1.42、-3.14μg/kg. And when there is no added nitrogen N2O were3.08、0.98、2.91mg/kg; CO2were96.36、227.88、156.96mg/kg; CH4were0.28、-1.64、0.6μg/kg. This suggested that nitrogen inputs to promote soil CO2emissions and changed the state of the soil CH4emission and absorption.5) Without adding nitrogen, soil DOC contents were significantly correlated with N2O emissions in different planting ages of tea soils, R2were0.668、0.920and0.793. There were correlations between soil CO2flux and soil DOC content of5and15years tea plantation, R2were0.668and0.775. After adding nitrogen, soil NH4+content and soil N2O of5and15years tea plantation had a significant correlation, R2were0.811and0.809. While soil DOC content was highly correlated with soil N2O and there was a significant correlations between soil CO2fluxes and DOC content, R2were0.866and0.826.