不同施氮水平对玉米生长季土壤呼吸的影响

为了探索不同氮肥用量对玉米（Zea mays）农田土壤呼吸速率的影响，采用EGM 4密闭式土壤呼吸测量系统，对甘肃省武威凉州灌区不同施氮水平下的玉米农田土壤呼吸速率进行研究。结果表明，玉米农田土壤呼吸速率的日变化为单峰曲线，其最小值和最大值分别出现在06:00和14:00左右，日变化随温度升高而增加。同时,玉米农田土壤呼吸速率(均以CO2的排放量计算)也具有较明显的季节变化，最大值为8.92 μmol/(m2·s)，出现在7月，最小值为1.12 μmol/(m2·s)，出现在5月，生育期变化顺序为抽雄期>大喇叭口期>拔节期>灌浆期>成熟期>苗期。土壤呼吸速率随施氮水平升高而升高，施氮450 kg/hm2（N450）排放CO2均值为5.72 μmol/(m2·s)；300 kg/hm2（N300）为5.34 μmol/(m2·s)；不施氮肥（N0）为4.90 μmol/(m2·s)，其中N450比N300和N0分别增加了7.12%和16.73%，N300比N0增加了8.98%，不同施氮水平下玉米土壤呼吸速率的差异主要发生在生长盛期。

Effects of fertilizing nitrogen levels on soil respiration during growing season in maize field

In order to explore effects of nitrogen(N) fertilization on soil respiration in maize(Zea mays) field during the growing season,the study,using EGM-4 sealed soil respiration measurement system,was conducted to measure Soil respiration rate of the maize fieild with different N fertilizatian at Liangzhou,Gansu Province.Results obtained in the study indicated that the soil respiration rate of maize field was changed on a similar diurnal pattern with a single peak,and increased with soil temperature rising up.The minimum and maximum values occurred around 06:00 and 14:00,respectively.The seasonal change of soil respiration rate in maize land was significant,with a CO2 emission maximum value of 8.92 μmol/(m2·s) on July and a minimum value of 1.12 μmol/(m2·s) on May.The order of seasonal change of soil respiration rate in maize field was tasseling stage>big-trumpet stage>elongation stage>filling stage>mature stage>seedling stage.Soil respiration rate increased with the increase of fertilizing nitrogen levels.Fertilized N with 450 kg/ha(N450),the CO2 emission from maize field was 5.72 μmol/(m2·s) on average;and fertilized N with 300 kg/ha(N300) and unfertilized N(N0),the CO2 emissions were 5.34 and 4.90 μmol/(m2·s) on average;whereas the soil respiration rate of N450 treatment was 7.12% and 16.73% higher than that of N300 and N0,respectively.However,the significant difference between treatments only occurred during the maize blooming stage.