添加玉米秸秆及其生物质炭对砖红壤N2O排放的影响

为比较秸秆和生物质炭对土壤氧化亚氮排放的影响,利用室内培养试验研究生物质炭、秸秆添加对土壤性质、硝化作用及N_2O排放的影响。试验设生物质炭、秸秆和空白3个处理,试验培养条件为30℃和75%田间持水量。结果表明,添加秸秆和生物质炭显著提高土壤pH、有机碳和速效K含量,其中秸秆对土壤pH的增加作用更为突出。与对照(1 604.82±168.93μgN_2O-N·kg~(-1))相比,添加秸秆和生物质炭减少N_2O排放量分别为58.0%和65.6%,但二者减排机理不同;秸秆对N_2O的减排因生物的氮固定,降低了硝化反应底物的有效性,生物质炭对N_2O减排可能源于硝化过程中较低的N_2O产生比例。由于生物质炭显著促进土壤硝化速率,而产生较多的NO_3~-,使得热带地区砖红壤硝态氮的淋失风险增大。

Effect of corn stalk and its biochar on N2O emissions from latosol soil

A 60-d incubation experiment was conducted to investigate the effects of corn stalk and its biochar additions on properties, nitri-fication and N2O emissions of latosol soil under 30 ℃ and 75% field water holding capacity. Three treatments including biochar addition, stalk addition and control(CK)were used. At the end of the experiment, both biochar and stalk additions significantly increased soil pH, organic C, and available K content, with greater effects observed in stalk addition. Compared with CK(1604±169μg N2O-N·kg-1), stalk and biochar additions significantly reduced cumulative N2O emissions by 58.0% and 65.6%, respectively. However, the mechanisms by which N2O emissions reduced were different for biochar- and stalk-treated soils. N2O reduction in stalk-treated soil was attributed to de-crease in the nitrification of NH+4 pool caused by increased NH+4 immobilization, while N2O reduction in biochar-treated soil was probably due to decreased N2O production ratio from nitrification. Biochar enhanced the nitrification rate and produced large NO-3 content, thus in-creasing the risk of nitrate leaching in tropical latosol soil.