生物炭施用下中国农田土壤N2O排放的Meta分析

Meta-analysis on farmland soil N_2O emissions under biochar application in China

为明确施加生物炭对中国农田土壤N_2O排放的影响和主要控制因素,以公开发表的试验数据为研究对象,采用Meta-analysis法定量分析了施加生物炭条件下,气候、土壤性质、田间管理方式、生物炭性质与施加量对土壤N_2O排放的影响,并对各影响因素进行通径分析。结果表明,当年降雨量≥600 mm时,生物炭显著降低土壤N_2O排放量(P<0.05),且随年降雨量的增加而增强;当年日照时数大于1 000 h时,生物炭对土壤N_2O的减排效果随年日照时数的增加而减弱。当土壤p H≥6.5时,生物炭对土壤N_2O的减排效果随土壤p H的增加呈先增后减趋势;在壤土中施加生物炭对N_2O的减排效果显著(P<0.05),而砂土和黏土不显著(P>0.05)。生物炭对覆膜土壤N_2O的减排效果优于不覆膜土壤;生物炭对土壤N_2O的减排效果随施氮肥量增加而减弱,而随生物炭比表面积的增加而增强。当生物炭C/N处于30~500时,生物炭施用下土壤N_2O排放量显著降低(P<0.05);当生物炭施加量处于20~160 t×hm-2时,生物炭对土壤N_2O的减排效果随施加量增加而增强。生物炭对土壤N_2O减排的影响存在显著的区域性特征,对华南、华东、华中和东北地区影响显著(P<0.05),而对西北地区不显著(P>0.05);施氮肥量、生物炭施加量、年均温和年降雨量是影响生物炭减排效果的最主要因素,这些因素的相互作用共同影响生物炭对土壤N_2O的减排效果。该研究可为生物炭在我国农区的推广应用和农田N_2O减排提供参考。

In this study,a Meta-analysis was conducted to make clear the effects of biochar application on soil N2O emissions and the main controlling factors in China.Based on observation data from published papers in the public domain,the effects of biochar application on soil N2O emissions were quantitatively analyzed under different climatic conditions,soil properties,field management practices and biochar properties.Then path analysis was used to determine the dominant factors influencing soil N2O emissions.The results showed that biochar application significantly decreased soil N2O emissions(P<0.05)under annual mean precipitation more than600mm,and the reduction effect was strengthened with increasing annual mean precipitation.Also when annual mean sunshine hours was greater than1000h,the N2O emission-reduction effect of biochar application decreased in trend following an initial increase with increasing annual mean sunshine hours.With increasing soil pH above6.5,soil N2O emission reduction first increased and then decreased under biochar application.Biochar application significantly decreased soil N2O emissions in loam soils(P<0.05),whereas the effects in sandy and clay soils were not significant(P>0.05).Moreover,the reduction in soil N2O emissions under film mulching was higher than that without film mulching.The effect of biochar on soil emission decreased with increasing nitrogen application rate,but increased with increasing specific surface area of biochar.When C∶N ratio of biochar was30?500,the effects of biochar application on soil N2O emissions was significant at P<0.05.When the amount of biochar was20?160t?hm?2,soil N2O emissions significantly decreased with increasing biochar application rate.Furthermore,significant differences in N2O emissions were observed for different regions under biochar application.For example,there was a significant reduction in N2O in South,East,Central and Northeast regions of China(P<0.05),except Northwest China(P>0.05).Generally,N fertilizer input,biochar application amount,annual mean temperature and annual mean precipitation were the dominant factors affecting the N2O emission-mitigation effects of biochar,which was controlled by the interactions among these factors.The study provided a reference base for the promotion of biochar technology in farming in China and emission reduction of soil N2O.