几种旱地农作物在农田N_2O释放中的作用及环境因素的影响

Role of several upland crops in N_2O emission from farmland and its response to environmental factors

用封闭箱法原位观测几种旱田Ｎ２Ｏ的排放通量，并与裸地Ｎ２Ｏ通量比较，评价植物在农田Ｎ２Ｏ释放中的作用．田间观测与室内模拟实验结合，考察环境因子对Ｎ２Ｏ通量的影响．结果表明１ｄ内大豆田Ｎ２Ｏ通量有两个释放高峰，而菠菜田和春小麦田只有１个释放高峰．种植大豆较大地提高了农田Ｎ２Ｏ的排放通量．农田裸地为一较弱的Ｎ２Ｏ释放源，且在１年的一定时期内表现为大气Ｎ２Ｏ的汇．光照变化对植物Ｎ２Ｏ通量影响很大，在较弱的光照条件下，植物释放Ｎ２Ｏ的通量较高．

The role of upland crops in N2O emission from farmland is evaluated by measuring N2O flux from several farniland ecosystems with closed chamber method,comparing with N2O flux from bare field. The effect of environmental factors on N2O flux its investigated by experiments in field and laboratory. The results show that there exists an emission peak of diurnal N2O flux both in the morning and in the afternoon from soybean field,but only one peak from spinach and spring wheat fields,which occurs in the afternoon and dusk,respectively. Plantation of soybean,which is less fertilized,strongly promotes the N2O emission from farmland with an average emission flux of 83. 8 μg·m-2· h-1. Bare field is a weak N2O source,whose emission rate is 1. 2 μg· m-2· h-1 in average,and can be a sink of atmospheric N2O from September to October,the flux rate being -11. 9μg· m-2·h-1. The variation of illumination has a significant influence on N2O flux from crop. Higher emission of N2O from aroid occurs under weak illumination.