不同灌溉措施下春玉米田间N_(2)O和CO_(2)日变化特征及影响因素研究

Study on the characteristics and influencing factors of daily variation of N_(2)O and CO_(2)in farmland under different irrigation measures

为探究西辽河平原浅埋滴灌下春玉米田N_(2)O和CO_(2)排放通量日变化特征及其影响因素,并确定1天中最佳观测时间。在春玉米吐丝期,采用静态暗箱-气相色谱法研究大水漫灌(CK)和浅埋滴灌(DG)处理N_(2)O和CO_(2)日排放动态变化特征,并分析其与土壤温度和湿度相关性。结果表明,在浅埋滴灌和大水漫灌两种灌溉方式下N_(2)O和CO_(2)排放具有明显的日变化特征,日变化趋势与大气温度变化相似,呈单峰型排放曲线,排放峰值均出现在观测当天大气温度达到最高值后2小时左右。大水漫灌N_(2)O和CO_(2)日排放通量均值分别为199.21μg·m^(-2)·h^(-1)、217.77 mg·m^(-2)·h^(-1);浅埋滴灌N_(2)O和CO_(2)日排放通量均值分别为235.82μg·m^(-2)·h^(-1)、253.54 mg·m^(-2)·h^(-1),分别较大水漫灌增加了18.38%和16.43%。相关性分析表明,浅埋滴灌和大水漫灌处理N_(2)O、CO_(2)排放通量日变化与地表温度和10 cm地温呈显著(P<0.05)或极显著相关(P<0.01),土壤温度是影响N_(2)O和CO_(2)排放日变化的重要因素。通过矫正系数随时间分布结果分析表明,上午08:00—10:00时间段测得浅埋滴灌N_(2)O和CO_(2)排放通量最接近全天排放通量均值,为N_(2)O和CO_(2)排放最佳观测时间。建议西辽河平原浅埋滴灌下春玉米田吐丝期后可以选取上午08:00—10:00监测N_(2)O和CO_(2)排放通量。

It aims to explore the diurnal variation characteristics and influencing factors of N_(2)O and CO_(2)emission fluxes in spring maize field under shallow burial drip irrigation in the Xiliaohe Plain,and to determine the best observation time in one day.During the silking stage of spring maize,the dynamic characteristics of daily emissions of N_(2)O and CO_(2)under flood irrigation(CK)and shallow burial drip irrigation(DG)were studied by static obscura-gas chromatography,and their correlations with soil temperature and humidity were analyzed.The results showed that N_(2)O and CO_(2)emissions had obvious diurnal variation characteristics under the two irrigation methods of shallow burial drip irrigation and flood irrigation.The diurnal variation trend was similar to that of atmospheric temperature,showing a unimodal emission curve,and the emissions both appeared about 2 hours after the atmospheric temperature reached the highest value on the observation day.The average daily emission fluxes of N_(2)O and CO_(2)in flood irrigation were 199.21μg·m^(-2)·h^(-1)and 217.77 mg·m^(-2)·h^(-1),respectively;the average daily emission fluxes of N_(2)O and CO_(2)in shallow burial drip irrigation were 235.82μg·m^(-2)·h^(-1)and 253.54 mg·m^(-2)·h^(-1),respectively,which increased by 18.38%and 16.43%respectively compared with flood irrigation.Correlation analysis showed that the diurnal changes of N_(2)O and CO_(2)emission fluxes were significantly(P<0.05)or extremely significantly(P<0.01)correlated with surface temperature and 10 cm ground temperature in the treatments of shallow burial drip irrigation and flood irrigation.Soil temperature was an important factor affecting the diurnal changes of N_(2)O and CO_(2)emission.The analysis of the time distribution of the correction coefficient showed that the N_(2)O and CO_(2)emission fluxes measured in the shallow burial drip irrigation during the time period of 08:00-10:00 am were closest to the average emission fluxes of the whole day,which was the best observation time for N_(2)O and CO_(2)emissions.It is suggested that the emission flux of N_(2)O and CO_(2)can be monitored from 08:00 to 10:00 in the morning after silking stage of spring maize field under shallow buried drip irrigation in Xiliaohe plain.