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依托甘肃农业大学布设在定西市李家堡镇的长期施氮定位实验,对不同施氮农田CH4和N2O气体通量,采用静态箱-气相色谱法进行小麦生育期的连续观测,并对影响通量变化的环境因子同期观测.结果表明:5个施氮处理下(0、52.5、105、157.5、210 kg·hm-2),旱作农田土壤在小麦全生育期内表现为CH4累积通量的汇和N2O累积通量的源;且不施氮处理时,CH4累积吸收通量最大;施氮量为210 kg·hm-2时,土壤CH4的累积吸收通量所受抑制最大,即土壤CH4累积吸收通量随施氮量升高而降低.相反,不施氮处理时,土壤N2O的累积排放通量最小,施氮量为210 kg·hm-2时,土壤N2O的累积排放通量最大,土壤N2O累积排放通量随施氮量的增加而增大.综合分析,施氮量增大会抑制全生育期旱作春小麦田土壤CH4吸收通量,提高土壤N2O的排放通量.因此,合理控制施氮量有利于生育期旱作农田土壤减排.CH4平均吸收通量随土壤温度的升高而降低,随土壤水分的升高而升高;相反,N2O平均排放通量随土壤温度的升高而升高,随土壤水分的升高而降低.5~10 cm层次的土壤温度与CH4平均吸收通量呈极显著线性负相关,与N2O平均排放通量呈显著正相关.5~10 cm层次的土壤水分与CH4平均吸收通量呈极显著线性正相关,与N2O平均排放通量呈显著负相关.
Relying on the experiment of long-term nitrogen application in Gansu Agricultural University in Lijiabao Town, Dingxi City, Gansu Agricultural University, continuous box-gas chromatography was used to observe the growth period of CH4 and N2O in different nitrogenous farmland. (0, 52.5, 105, 157.5 and 210 kg · hm-2) under different nitrogen application rates. The results showed that soil moisture in dry farmland showed a cumulative flux of CH4 during the whole growth period of wheat And the source of N2O fluxes. When the nitrogen was not applied, the cumulative flux of CH4 was the largest. When the nitrogen application rate was 210 kg · hm-2, the cumulative flux of CH4 in soil was the largest, that is, the soil The cumulative fluxes of CH4 decreased with the increase of nitrogen application rate. On the contrary, the cumulative fluxes of N2O in the soil were the least when the nitrogen application was not applied. When the nitrogen application rate was 210 kg · hm-2, the cumulative fluxes of N2O And the N 2 O flux increased with the increase of N application rate.A comprehensive analysis showed that the increase of N application could inhibit the soil CH 4 uptake and increase the soil N 2 O flux during the whole growth period.Therefore, Reasonable control of N application rate is conducive to the reduction of soil moisture in dry farming cropland during the growth period.CH4 average fluxes On the contrary, the average fluxes of N2O increased with the increase of soil temperature, and decreased with the increase of soil moisture. On the contrary, the average fluxes of N2O decreased with the increase of soil moisture, There was a significant linear negative correlation between soil temperature and average CH4 flux and a significant positive correlation with average N2O fluxes. Soil moisture at 5 ~ 10 cm was significantly and linearly positively correlated with CH4 average flux, There was a significant negative correlation between emission fluxes.