添加生物黑炭对茶园土壤CO2、N2O排放的影响

采用室内培养试验,研究了不同生物黑炭施用量对两种茶园土壤(红壤和黄壤)CO₂、N₂O排放特征的影响。生物黑炭用量设5个水平:H0(0 g·kg^-1)、H1(3.56 g·kg^-1)、H2(7.11 g·kg^-1)、H3(14.22 g·kg^-1)、H4(28.44 g·kg^-1).结果表明:红壤茶园土壤CO₂排放量显着高于黄壤,N₂O排放总量则低于黄壤;与H0处理相比,施用低量的生物黑炭(H1)对两种茶园土壤CO₂排放无显着影响;高量的生物黑炭处理(H3、H4)则显着增加土壤CO₂排放量,增幅为20%~47%(P<0.05).生物黑炭施用后(H2、H3、H4)明显降低两种茶园土壤N₂O释放速率及反硝化损失率,土壤N₂O排放总量降幅为37%~63%(P<0.05),反硝化损失量降幅22%~54%(P<0.05),且均随着生物黑炭施用量增加而增大。此外,从土壤pH值、无机氮含量和硝化率角度,探讨了生物黑炭影响茶园土壤CO₂和N₂O排放的因素。

Effects of Biochar on CO2 and N2O Emissions from Tea Garden Soils

Biochar has shown many benefits in the agriculture and environment. This study investigated the effects of biochar additions on carbon dioxide(CO₂) and nitrous oxide(N₂O) emissions from tea garden soils(red soil and yellow soil) in an incubation experiment. The soils were treated with varying doses of biochar(H0=0 g·kg^-1, H1=3.56 g·kg^-1, H2=7.11 g·kg^-1, H3=14.22 g·kg^-1 and H4=28.44 g·kg^-1). The gases were sampled on the day 2, 4, 6, 10, 14, 18, 25, 32, 39 and 46 of treatment. The CO₂ emissions from red tea garden soil were higher than those from yellow tea garden soil(P<0.05), while the N₂O emissions were less in red than in yellow tea garden soil. Compared with control(H0), biochar at H1 had no significant effects on CO₂ flux rates, but significantly increased CO₂ emission by 20% to 47%(P<0.05) in two soils at H3 and H4. However, biochar treatments reduced N₂O emissions and denitrification rates from two soils in a dose-dependent manner. At higher biochar rates(H2, H3 and H4), N₂O flux and denitrification rates decreased by 37% to 63%(P<0.05) and 22% to 54%(P<0.05), respectively, in two soils. The mechanisms of CO₂ and N₂O emission inhibition by biocharpH value, inorganic nitrogen(NH₄⁺ and NO₃^-) and nitrification rates] were discussed in this paper.