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为揭示水肥用量对农田生态系统土壤CO_2排放的综合影响,试验设高水W1(90 mm)、中水W0.85(76.5 mm)、低水W0.7(63 mm)这3个灌水水平,300、255、210和0 kg·hm~(-2)这4个施氮水平和90、76.5、63和0 kg·hm~(-2)这4个施磷水平,采用静态暗箱-气相色谱法对夏玉米地土壤CO_2排放进行原位观测,分析土壤CO_2排放对水肥调控的动态响应.结果表明,玉米季农田土壤CO_2排放呈双峰曲线,主峰值出现在拔节期至抽雄期,次峰出现在抽雄至灌浆期,其他阶段排放通量较低.W1在高肥F1(N 300 kg·hm~(-2),P2O590 kg·hm~(-2))和低肥F0.7(N 210 kg·hm~(-2),P2O563 kg·hm~(-2))水平下全生育期土壤CO_2平均排放通量均显著高于W0.7(P<0.05);中肥F0.85(N 255 kg·hm~(-2),P2O576.5 kg·hm~(-2))和F0.7水平下,W0.85与W0.7差异不显著(P>0.05).W1水平下,F1比F0.7显著增大14.82%(P<0.05);W0.85水平下,F0.85比F0.7显著增大8.03%(P<0.05);而W0.7水平下各施肥水平间无显著性差异.单施氮(N 210 kg·hm~(-2))或磷(P2O563 kg·hm~(-2))、氮磷配施(N 210 kg·hm~(-2)、P2O563kg·hm~(-2))较不施肥处理分别显著增加23.70%、19.00%和12.30%,且氮磷交互作用极显著(P<0.01).方差分析表明,供应水平相差15%时,水肥交互作用对全生育期土壤CO_2平均排放通量影响不显著(P>0.05),而对土壤CO_2累计排放量影响显著(P<0.05);供应水平相差30%时水肥交互作用对全生育期土壤CO_2平均排放通量和累计排放量均影响显著(P<0.05).可见,灌水量、施氮量、施磷量单因素均显著促进土壤CO_2排放,而氮磷配施起抑制作用.土壤CO_2排放与水、肥供应水平均有密切关系,水肥交互显著促进了土壤CO_2排放,通过水肥联合调控可有效调节土壤CO_2排放.
In order to reveal the combined effect of water and fertilizer on CO 2 emission from farmland ecosystem, three irrigation levels of W1 (90 mm), W0.85 (76.5 mm) and W0.7 (63 mm) Four nitrogen application rates of 300, 255, 210 and 0 kg · hm -2, and four phosphorus application levels of 90, 76.5, 63 and 0 kg · hm -2, respectively. The static black box-gas chromatography Method was used to observe the CO_2 emission from summer maize field in situ and to analyze the dynamic response of soil CO_2 emission to the regulation of water and fertilizer.The results showed that the CO_2 emission in farmland of corn field showed a bimodal curve with the main peak appeared at jointing stage to tasseling stage, Appeared in the heading stage and the grain filling stage, while the discharge flux was lower in the other stages.W1 was positively correlated with the yield of high fat F1 (N 300 kg · hm -2, P 2 O 590 kg · hm -2) and low fertilizer F 0.7 (P <0.05). The average fluxes of CO 2 in soils under 210 kg · hm -2, P 2 O 5 63 kg · hm -2 were significantly higher than those on W0.7 (P <0.05) W0.85 and W0.7 had no significant difference (P> 0.05) under the condition of N 255 kg · hm -2, P 2 O 5 76.5 kg · hm -2 and F 0.7, F1 was significantly increased by 14.82% (P <0.05) compared with F0.7; F0.85 was significantly increased by 8.03% (P <0.05) at F0.85 compared with F0.7 at W0.85; No significant difference (N 210 kg · hm -2 or P 2 O 5 63 kg · hm -2) and N 210 kg · hm -2 (P 2 O 5 63 kg · hm -2) (-2) increased significantly by 23.70%, 19.00% and 12.30% compared with no fertilization treatment, and the interaction between nitrogen and phosphorus was extremely significant (P <0.01) .Analysis of variance showed that the interaction of water and fertilizer was (P <0.05), but had a significant effect on the cumulative CO 2 emission (P <0.05). When the supply level was 30% different, the interaction of water and fertilizer had no significant effect on the average CO 2 emission during the whole growth period (P <0.05) .It can be seen that the single factor of irrigation amount, N application rate and P application rate significantly promoted the soil CO 2 emission and the combination of N and P. Co-emission of soil CO 2 with water, Fertilizer supply levels are closely related to the interaction of water and fertilizer significantly promoted soil CO 2 emissions through soil and water regulation can effectively regulate soil CO 2 emissions.