水氮耦合对设施土壤温室气体排放的影响

为探究水氮耦合对设施土壤温室气体排放的影响,基于连续5年的设施番茄水氮调控定位试验,比较分析了水氮耦合对土壤N_2O、CO_2和CH_4排放通量和累积排放量的影响,并估算了温室气体的全球增温潜势(GWP)和温室气体排放强度(GHGI)的差异。田间小区试验设置不同灌水下限(W1:25 kPa、W2:35 kPa、W3:45 kPa)和施氮量(N1:75 kg N·hm~(-2)、N_2:300 kg N·hm~(-2)、N3:525kg N·hm~(-2))组合共9个处理。结果表明:设施土壤N_2O和CO_2排放通量受灌水施肥时期的影响,施肥后N_2O排放通量呈增加趋势,高灌水量(低灌水下限25 kPa)促进N_2O和CO_2排放。CH_4的排放通量表现为中等和强变异的特点。除水氮交互对CO_2累积排放总量和施氮量对CH_4累积排放总量影响不显著外,灌水下限、施氮量和水氮交互作用对N_2O、CO_2、CH_4累积排放总量、GWP、GHGI和番茄产量的影响显著或极显著。随氮肥用量的增加,N_2O累积排放总量增加。N_2O和CO_2累积排放总量与GWP之间均达到极显著正相关,且各处理N_2O对GWP平均贡献率为5.25%,CO_2为94.59%。适当减少氮肥用量和增加灌水下限能够有效地降低温室气体排放和减缓全球变暖。W2N1处理是本研究中减缓温室气体排放并提高番茄产量的最佳水氮管理措施。

Interactive effect of irrigation and nitrogen fertilization on greenhouse gas emissions from greenhouse soil

This study conducted an experiment on greenhouse grown tomatoes to explore the interactive effect of irrigation and nitrogen application on the level of greenhouse gas emissions released from greenhouse soil, and to determine the impact of this effect on emission flux and total cumulative emission of greenhouse gases (N₂O, CO₂ and CH₄). Furthermore, this study examined differences in global warming potential (GWP)and greenhouse gas intensity (GHGI)between the gases over a five-year experimental period. Nine treatments, comprised of a combination of three irrigation lower limits (W₁:25 kPa, W₂:35 kPa, W₃:45 kPa)and three N application rates (N₁:75 kg N·hm^-2, N₂:300 kg N·hm^-2, N₃:525 kg N·hm^-2), were utilized in the experiment. Results showed that the effects of irrigation and fertilization time influenced the emission fluxes of N₂O and CO₂. N₂O emission flux increased after fertilization, and the high irrigation rate (irrigation lower limit 25 kPa)raised the emission fluxes of both N₂O and CO₂. The variability coefficients of CH₄ emission flux were in the middle to strong range. Except for the interactive effect of irrigation and nitrogen on the total cumulative emission of CO₂, and the effect of nitrogen fertilization on the total cumulative emission of CH₄, irrigation and nitrogen fertilizer rates and their interactions had a very significant effect on tomato yield, GWP, GHGI, and the total cumulative emission of N₂O, CO₂, and CH₄. Additionally, as nitrogen fertilizer rates increased, the total cumulative emission of N₂O also increased. The total cumulative emission of N₂O and CO₂ had a significant, positive correlation with GWP; the average contribution rate of N₂O to GWP was 5.25% compared with a GWP of 94.59% for CO₂. Ultimately, reducing the nitrogen fertilizer rate and increasing the irrigation lower limit could effectively reduce greenhouse gas emissions and ameliorate global warming. In this study, W₂N₁ treatment provided the optimal regulation of irrigation and nitrogen fertilization needed to increase tomato yield and mitigate greenhouse gas emissions.