Effect Of Biochar Addition On Greenhouse Gases Emission And Nitrogen Loss From Tea Planted Soil

Excessive fertilizer input in tea garden will produce more greenhouse gases emission and nitrogen loss.In this study,tea garden soils of two different planting years(10Y,40Y)were used to conduct a indoor experiment with different biochar rates and application manners to figure out the behavior of greenhouse gases(N2O,CH4,and CO2)emission and nitrogen(NH4+-N?NO3--N)leaching from tea planted soil.Furthermore,a field experiment in situ was also arranged to reveal the nitrogen runoff loss after rain under fertilizer reduction(10%and 20%declining as compared to local fertilization level)and biochar addition(at 10 t/ha).The detailed results are presented as follows:(1)40 years tea planted soil showed lower N2O basic emission rate but higher basic CH4 and CO2 basic emission rate.Biochar addition reduced N2O and CH4 emission and the more biochar added,the less N2O and CH4 emitted.CO2 emission was increased with biochar application;more CO2 was emitted when higher biochar added.Biochar adding manner significantly affected N2O emission,biochar mixing with topsoil(0-10 cm)reduced more N2O emission than that of biochar applying on soil surface.6.95%?42.44%equallying overall CO2-eq emission of N2O and CH4 was reduced in 10 years tea planted soil with biochar adding.meanwhile 7.61%?43.66%of equalling CO2-eq emission of N2O and CH4 reduced in 40 years tea planted soil with biochar adding.(2)Higher NH4+-N basic leaching level and lower NO3--N basic leaching level were found in 40 years tea planted soil.Biochar addition reduced NH4+-N leaching efficiently and the more biochar added,the less NH4+-N leached;while NO3--N leaching was increased when biochar added and the high level of NO3--N leaching appeared at the higher biochar added.Biochar adding manner significantly affected NH4+-N leaching,when in 1%rate,biochar mixing with topsoil reduced more NH4+-N leaching than that of biochar applying on soil surface;while in 5%rate,biochar mixing with topsoil reduced less NH4+-N leaching than that of biochar applying on soil surface.(3)Biochar addition coordinating with fertilizer reduction was effective to control nitrogen runoff loss from tea garden.Biochar addition coordinating with fertilizer reduction significantly decreased nitrogen concentration in runoff in a short time after fertilization(within a week).In about two months rainy season,10%fertilizer reduction decreased 7.40%,12.84%and 12.29%of NH4+-N,NO3--N and TN runoff loss respectively;20%fertilizer reduction decreased 22.89%,26.05%and 26.74%of NH4+-N5 NO3--N and TN runoff loss respectively.Biochar(10 t/ha)application additionally reduced NH4+-N,TN but NO3--N runoff loss on the basis of fertilizer reduction.Biochar addition(10 t/ha)coordinating with 10%and 20%fertilizer reduction supply(as compared with local normal N rate)reduced 15.83%and 33.81%TN runoff loss from the two months rainy season respectively.