喷涂吡啶尿素对夏玉米/冬小麦轮作体系温室气体排放的影响

Effects of different nitrapyrin-nitrogen(N)fertilizer application rates on greenhouse gas emissions in the maize and wheat rotation system

过量施用氮肥增加农田温室气体的排放,通过监测农田温室气体排放量寻求合理的氮素减排措施对农业生产有重要作用。本研究设置3个不同梯度喷涂吡啶尿素水平(N1-3)及不施氮肥(N0),在夏玉米和冬小麦生长期间采用静态箱法收集气体,研究土壤CO_2、CH_4和N_2O的排放特征,定量评价不同用量喷涂吡啶尿素的综合增温潜势。结果表明:不同喷涂吡啶尿素用量下的温室气体排放具有明显的季节性变化特征。玉米和小麦季土壤CO_2排放通量具有明显的季节性排放规律。CO_2平均排放通量小麦季明显低于玉米季,而CO_2累积排放量小麦季则高于玉米季;各施氮处理玉米和小麦季基肥和追肥后均出现显著的N_2O排放峰。整个轮作季,随喷涂吡啶尿素用量的增加,土壤对大气CH_4的交换通量有所降低,而土壤排放CO_2和N_2O的量有所增加。CO_2的综合增温潜势(GWP)对轮作系统总GWP贡献最大,而CH_4很小。玉米和小麦季各喷涂吡啶尿素处理的总GWP均高于对照;玉米季各处理的净GWP均为正值,是温室气体排放的一个源;而小麦季各处理的净GWP均为负值,是温室气体排放的一个汇。说明玉米/小麦轮作体系的综合增温潜势随施氮肥量的增加而增加,合理减施氮肥可以有效降低大气增温效应。

Excessive nitrogen fertilization can increase the greenhouse gas emission. It is important for agricultural production to find the reasonable nitrogen reduction measures by determining the greenhouse gas emission. Three different nitrapyrin-N fertilizer rates （N1 -3）and no N control （NO）were set up to collect gas using static chamber method to study on soil CO2, CH4 and N2O emission characteristics during maize and wheat growth stages. At the same time, the comprehensive warm potential of different dosages of pyridine spraying urea potential was quantitatively evaluated. There were obvious seasonal characteristics of greenhouse gase emissions under different nitrapyrin-N fertilizer rates. There was an obvious seasonal variation of the emission fluxes of CO2 in maize and wheat season. The average emission flux of CO2 in wheat season was significantly lower than that in maize,while the cumulative emissions was on the contrary. There was a soil N2O emission peak after basal or topdressing fertilizer of different nitrapyrin-N application rates in maize and wheat season. For the whole rotation system, with the increase of nitrapyrin-N rates, soil CH4 emission was decreased, while soil N2O and CO2 emission were increased. The global warming potential （GWP）of total greenhouse gas from rotation system was mainly determined by CO2, and little by CH4. The total GWP of different nitrapyrin-N rates in maize and wheat season was higher than that in the control, so fertilization increased the soil greenhouse gas warming capabilities. The positive net GWP in maize season indicated that the maize field was a source of greenhouse gas, and the net negative GWP in wheat season showed the wheat field was a sink of greenhouse gas. It also showed that GWP in the maize and wheat rotation system increased with the nitrogen application rate increase. Therefore,we should scientifically control N fertilizer rates to reduce the soil greenhouse gas warming capabilities.