摘要
本文介绍了农田N2O排放连续自动测定系统的方法原理、系统整体构造和气路配置,并通过对华北平原旱地土壤夏玉米季N2O排放的连续观测,比较了连续自动测定方法与传统手动间歇取样测定方法的差异。结果表明,夏玉米季N2O排放具有明显的日排放规律,且在三叶期和十叶期施肥后存在明显的释放高峰;通过选取7:20、8:30、9:40、10:50、12:00、13:20、14:30、15:40、16:50和18:00不同采样时间的测定结果,分别模拟了间隔为3d和6d的排放总量,结果表明,间隔取样的累积排放结果与连续观测结果的差异,与采样当天中具体的采样时间紧密相关,间隔估算结果随着采样时间的延后具有先升高后降低的趋势,与N2O的日排放规律相一致。本研究中,不同时间间隔对估算结果影响不明显。
A continuous automatic measurement system was set up to measure N2O emissions from a summer maize field in Beijing suburb in 2002. This system consisted of 9 static chamber units, a pneumatic unit, a sampling unit, a sample injection unit, a sample splitting unit and a gas chromatograph (GC) . The chambers were adjustable in height from 0.25 m for young plants to 2.25 m for fully developed maize plants with a covered soil area being 1.4 by 1.4 m (1.96 m2). N was top dressed in the three leaf stage (Jul 16, 2002) with a dose of 100 kg/hm2 N(as ammonium biocarbonate ) and in the ten-extended-leaf stage (Aug 14, 2002) with a dose of 200 kg/hm2 N (as urea) , separately. The diurnal, seasonal variation of N2O flux as well as the influences of sampling time and sampling frequencies on the simulated results of N2O emission were studied in the paper.A large seasonal variation of N2O emission was observed during the summer maize season. There were two emission peaks which took placed 2 weeks after N fertilizer applied in the three leaf stage and the ten-extended leaf stage accounting for 22.8% and 64.8% of the total emission in whole growth season, respectively. The diurnal variation of N2O showed that the maximum N2O flux rate occurred at 11:00- 14:00, and the minimum flux of N2O occurred at 2:00 - 5: 00, which was coinciding to the diurnal variation of soil temperature. The accumulated N2O emissions based on the different sampling time and sampling frequencies showed that the sampling time strongly affected the calculated N2O emission because of the diurnal variation of N2O emission; while sampling frequencies had on influence on simulated results in this study.
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2005年第1期64-70,共7页
Journal of Plant Nutrition and Fertilizers
基金
国家自然科学基金重大项目(30390084)北京市自然科学基金重大项目(6010001)资助。
关键词
N2O
夏玉米
连续自动测定
N2O emission
summer maize
continuous automatic measurement
