3种豆科植物生物质炭对海南砖红壤性质及N_2O排放的影响

Influence of three biochars produced by three leguminosae plants on Hainan latosol properties and N_2O emission

【目的】探讨不同豆科植物在不同温度条件下制备的生物质炭对砖红壤性质及N_2O排放的影响,筛选出既有助于N_2O减排又有益于土壤改良的豆科作物类型,为海南豆科植物材料的合理利用提供理论依据。【方法】采集海南3种常见豆科植物材料(花生、大豆和柱花草),在300、500和700℃不同热解温度下制备9种生物质炭,并设不加生物质炭为对照(CK),开展室内培养试验并进行气体采集,测定培养过程中土壤N_2O排放、矿质氮含量变化及其基本理化性质。【结果】不同生物质炭处理可显著提高土壤p H和速效钾含量(P<0.05,下同),也可明显提高土壤有机碳和全氮含量,其中以大豆秸秆生物质炭处理的土壤p H及有机碳、全氮、速效磷和有效钾含量增幅较大。300℃下制备的生物质炭可明显促进N_2O排放,500和700℃下制备的生物质炭对N_2O排放的影响因制备材料不同而存在差异。随培养时间的延续,各处理的土壤铵态氮(NH_4^+-N)含量逐渐降低,硝态氮(NO_3^--N)含量逐渐增加;培养结束后,生物质炭处理的土壤NH_4^+-N含量基本接近0 mg/kg,而土壤NO_3^--N含量介于71.06~93.09 mg/kg。相同材料制备的生物质炭处理,温度越高其土壤硝化率上升越快,至培养结束时,各生物质炭处理的土壤硝化率均接近100.00%,CK的硝化率为90.57%(低于各生物质炭处理)。【结论】综合考虑不同生物质炭对土壤性质及N_2O排放的影响,建议选用大豆秸秆在500℃下制备的生物质炭进行热带砖红壤改良。

【Objective】The effects of biochar prepared by different leguminosae plants under different temperatures on the properties of latosol and N2O emission were studied to select the suitable raw leguminosae materials which could contribute to N2O emission reduction and soil improvement,and provide theoretical basis for rational utilization of leguminosae plants in Hainan.【Method】Three common leguminosae plants in Hainan(peanut,soybean and stylosanthes)were sampled,and were produced into nine biochars under pyrolysis temperature300,500and700℃.Indoor cultivation experiment was conducted with application of these biochars.During the experiment,the air was collected to measure N2O emission from soil,mineral nitrogen content variation and soil physicochemical properties.Cultivation without biochar was set as control(CK).【Result】Different biochar treatments could significantly increase soil pH and available potassium(P<0.05,the same below),and enhanced soil organic carbon and total nitrogen contents.The biochar made by soybean straw could largely increase soil pH,organic carbon,available phosphorus and available potassium contents.Biochar produced at300℃effectively stimulated soil N2O emission.Effects of biochar produced at500and700℃on soil N2O emission varied as the materials differed.With culture time prolonged,ammonium nitrogen(NH4+-N)content in soil under different treatments decreased while nitrate nitrogen(NO3--N)content increased on the contrary.At the end of the culture,NH4+-N content in soil treated by biochars was close to0mg/kg,and NO3--N content in soil was71.06-93.09mg/kg.In terms of biochar made by the same materials,as the temperature rose,soil nitrification rate increased.At the end of culture,soil nitrification rate in biochar treated groups was close to100.00%,but that of CK was90.57%which was lower than biochar treatments.【Conclusion】Taking the effects of different biochars on soil properties and N2O emission into consideration,biochar produced by soybean straw at500℃was recommended to improve latosol in tropical region.