有机肥替代化肥对砂姜黑土区小麦-玉米轮作系统N_(2)O排放的影响

Effect of Organic Fertilizer Replacing Chemical Fertilizer on Nitrous Oxide Emission from Wheat-Maize Rotation System in Lime Concretion Black Soil

【目的】探究有机肥替代化肥条件下砂姜黑土区小麦-玉米轮作系统N_(2)O排放特征及与土壤环境因子的关系,为实现农田温室气体减排提供理论依据。【方法】以砂姜黑土区小麦-玉米轮作系统为研究对象,采用静态箱-气相色谱法与常规土壤参数分析相结合,研究不施肥(CK)、常规施肥(CF)、有机肥氮替代20%化肥氮及有机肥氮替代40%化肥氮(R2FM及R4FM,有机肥于小麦季施用)对小麦-玉米轮作系统N_(2)O排放的影响及与关键驱动因子的关系。【结果】R2FM及R4FM处理小麦产量显著高于CF处理,增幅分别为12.2%和10.2%,而不同施肥处理之间玉米产量无显著差异。CK、CF、R2FM及R4FM处理周年N_(2)O平均排放通量分别为5.9、50.3、43.9及39.6μg·m^(-2)·h^(-1),其中小麦季为3.1、23.6、25.0及26.4μg·m^(-2)·h^(-1),玉米季为8.8、77.0、62.8及52.9μg·m^(-2)·h^(-1);不同施肥处理下N_(2)O排放通量与土壤NO_(3)^(-)-N含量呈极显著正相关,同时还与小麦季土壤温度、玉米季土壤含水量呈显著或极显著正相关。CF、R2FM及R4FM处理周年N_(2)O累积排放量分别为2.38、2.44及2.53 kg·hm-2,较CK处理(0.56 kg·hm-2)显著增加325%—354%,N_(2)O-N排放系数为0.40%—0.44%,但CF、R2FM及R4FM处理之间周年N_(2)O累积排放量、N_(2)O-N排放系数均无显著差异。不同施肥处理下季节性N_(2)O累积排放量存在差异,与CF处理相比,R2FM及R4FM处理在小麦季N_(2)O累积排放量分别显著提高28.3%和62.6%,且二者N_(2)O-N排放系数(0.35%和0.41%)显著增加,而在玉米季N_(2)O累积排放量分别显著降低15.8%和33.8%;N_(2)O累积排放量与小麦季土壤全氮、碱解氮、微生物量碳含量及玉米季土壤全氮含量呈显著或极显著正相关,而与玉米季土壤有机碳含量呈显著负相关。【结论】在有机肥氮替代化肥氮条件下,优化小麦季施肥管理是减少砂姜黑土区小麦-玉米轮作系统N_(2)O排放的关键。

【Objective】Under the condition of organic fertilizer replacing chemical fertilizer,the relationship between nitrous oxide(N_(2)O)emissions and soil environmental factors in wheat-maize rotation system of lime concretion black soil was researched,which could provide theoretical basis for greenhouse gas emission reduction from farmland.【Method】In this study,taking wheat-maize rotation system of lime concretion black soil as research object,the effects of no fertilization(CK),conventional fertilization(CF)and organic fertilizer-N replacing 20%or 40%of chemical fertilizer-N(R2FM and R4FM,organic fertilizer-N were applied in the wheat season)on N_(2)O emissions and environmental factors driving N_(2)O emissions were analyzed by the method of static box-gas chromatography and conventional soil parameter analysis.【Result】The wheat yields under R2FM and R4FM were significantly increased by 12.2%and 10.2%than those under CF,respectively,but there was no significant difference in the maize yields between fertilization treatments.Average annual N_(2)O emission fluxes under CK,CF,R2FM,and R4FM were 5.9,50.3,43.9 and 39.6μg·m^(-2)·h^(-1),with 3.1,23.6,25.0 and 26.4μg·m^(-2)·h^(-1)in the wheat season and 8.8,77.0,62.8 and 52.9μg·m^(-2)·h^(-1)in the maize season,respectively.Under fertilization treatments,N_(2)O emission fluxes were significantly positively correlated with soil NO_(3)^(-)N in the whole season,as well as soil temperature in the wheat season and soil water content in the maize season.Cumulative annual N_(2)O emissions were 2.38,2.44 and 2.53 kg·hm-2 for CF,R2FM and R4FM,which were significantly increased by 325%-354%in comparison to CK(0.56 kg·hm-2),and the range of their emission factors was 0.40%-0.44%.However,there was no significant difference between cumulative annual N_(2)O emissions or N_(2)O-N emission factors under CF,R2FM and R4FM.Cumulative seasonal N_(2)O emissions were obviously different between fertilizer treatments,such as R2FM and R4FM significantly increased cumulative N_(2)O emissions by 28.3%and 62.6%in the wheat season in comparison to CF,and their N_(2)O-N emission factors(0.35%and 0.41%)were also significantly increased,but they significantly decreased cumulative N_(2)O emissions by 15.8%and 33.8%in the maize season,respectively.Cumulative N_(2)O emissions were significantly positively correlated with soil total nitrogen,alkali-hydrolyzable nitrogen,microbial biomass carbon in the wheat season as well as soil total nitrogen in the maize season,but they were significantly negatively correlated with soil organic carbon in the maize season,respectively.【Conclusion】Under the condition of organic fertilizer-N replacing chemical fertilizer-N,optimizing fertilization management in the wheat season is the key to reduce N_(2)O emissions from wheat-maize rotation system in lime concretion black soil.