施肥与灌溉对春玉米土壤N2O排放通量的影响

N_2O Flux Variations from Spring Maize Soil Under Fertilization and Irrigation

2007年在山西省榆次县利用静态箱自动监测系统对传统和优化两种施肥方式下春玉米土壤追肥和灌溉前后N2O排放通量进行了连续测定,该地区土壤质地为壤土,气候为温带大陆性半干旱气候。结果表明,灌溉和施肥对N2O的排放影响较大,当土壤含水量较低时,施肥并不会导致N2O通量迅速升高。在不灌溉的条件下施肥前后N2O的日排放通量特征为单峰型,凌晨4:00左右为最低值,下午16:00左右达到最高值,与空气和5cm土壤温度相关性均达到了极显著水平。施肥并灌溉后N2O排放通量迅速升高,一天之内能够迅速升高约50倍。灌溉后N2O日排放通量呈"N"字型走势,在达到最大值后变为单峰型,一周后日排放出现了直线下降和水平波动两种不同的走势。经检验施肥并灌溉后一周内优化施肥方式下N2O排放通量极显著低于传统施肥方式(P<0.01),优化施肥可以作为减排农田N2O排放的措施之一。

N2O flux variations from spring maize soil under traditional and optimized fertilization were monitored continuously using automatic static chamber system in Yuci County, Shanxi Province in 2007. The results showed that ： Nitrous oxide flux was mainly affected by irrigation and fertilization. However, fertilization wouldn＇t result in high N2O flux immediately if the soil water content is lower. Before and after fertilization without irrigation, the pattern of diurnal N2O flux was in a single peak type. Lowest N2O flux appeared at about 4am and highest N2O flux occurred at about 4pm. N2O flux had a very significant relative with air temperature and soil temperature at 5 cm. After fertilization and irrigation the N2O flux increased 50 times in one day. Diurnal N2O flux dynamic showed an ＂N＂ shape, then the diurnal N2O flux dynamic was in a single peak shape after the N2O flux reached the maximum value. Diurnal N2O flux dynamic shown two different types one week later： sharply linear fall and horizontal fluctuation. N2O flux with optimized fertilization was very significant lower than that with traditional fertilization （P〈0.01）. Therefore, the optimized fertilization can be an option for reducing N2O emission from cropland.