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首页> 外文期刊>Global change biology >Methane and nitrous oxide fluxes in annual and perennial land-use systems of the irrigated areas in the Aral Sea Basin
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Methane and nitrous oxide fluxes in annual and perennial land-use systems of the irrigated areas in the Aral Sea Basin

机译：咸海流域灌区年度和多年生土地利用系统中的甲烷和一氧化二氮通量

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摘要

Land use and agricultural practices can result in important contributions to the global source strength of atmospheric nitrous oxide (NO) and methane (CH). However, knowledge of gas flux from irrigated agriculture is very limited. From April 2005 to October 2006, a study was conducted in the Aral Sea Basin, Uzbekistan, to quantify and compare emissions of NO and CH in various annual and perennial land-use systems: irrigated cotton, winter wheat and rice crops, a poplar plantation and a natural Tugai (floodplain) forest. In the annual systems, average NO emissions ranged from 10 to 150 og NO-N mpo hp# with highest NO emissions in the cotton fields, covering a similar range of previous studies from irrigated cropping systems. Emission factors (uncorrected for background emission), used to determine the fertilizer-induced NO emission as a percentage of N fertilizer applied, ranged from 0.2% to 2.6%. Seasonal variations in NO emissions were principally controlled by fertilization and irrigation management. Pulses of NO emissions occurred after concomitant N-fertilizer application and irrigation. The unfertilized poplar plantation showed high NO emissions over the entire study period (30 og NO-N mpo hp#), whereas only negligible fluxes of NO (<2 og NO-N mpo hp#) occurred in the Tugai. Significant CH fluxes only were determined from the flooded rice field: Fluxes were low with mean flux rates of 32 mg CH mpo dayp# and a low seasonal total of 35.2 kg CH hap#. The global warming potential (GWP) of the NO and CH fluxes was highest under rice and cotton, with seasonal changes between 500 and 3000 kg CO eq. hap#. The biennial cotton-wheat-rice crop rotation commonly practiced in the region would average a GWP of 2500 kg CO eq. hap# yrp#. The analyses point out opportunities for reducing the GWP of these irrigated agricultural systems by (i) optimization of fertilization and irrigation practices and (ii) conversion of annual cropping systems into perennial forest plantations, especially on less profitable, marginal lands.
机译：土地使用和农业实践可以为全球大气中的一氧化二氮（NO）和甲烷（CH）的强度做出重要贡献。但是，灌溉农业产生的气体通量的知识非常有限。从2005年4月到2006年10月，在乌兹别克斯坦的咸海盆地进行了一项研究，以量化和比较各种年度和多年生土地利用系统中的NO和CH排放：灌溉棉花，冬小麦和水稻作物，白杨人工林和天然的Tugai（泛滥）森林。在年度系统中，平均NO排放量在10至150 og NO-N mpo hp＃范围内，其中棉田中的NO排放量最高，涵盖了以前与灌溉耕种系统相似的研究范围。用于确定肥料引起的NO排放量（占施用的氮肥的百分比）的排放因子（未经背景排放校正）范围为0.2％至2.6％。 NO排放量的季节性变化主要由施肥和灌溉管理控制。施用氮肥和灌溉后出现NO排放脉冲。未受精的杨树人工林在整个研究期内均表现出较高的NO排放量（30 og NO-N mpo hp＃），而图加地区仅发生了可忽略的NO通量（<2 og NO-N mpo hp＃）。仅从淹没的稻田中确定了重要的CH通量：通量较低，平均通量率为32 mg CH mpo dayp＃，季节性总通量较低，为35.2 kg CH hap＃。在稻米和棉花下，NO和CH通量的全球变暖潜能值（GWP）最高，CO当量在500至3000 kg CO eq之间变化。 hap＃。该地区通常实行的两年一度的小麦-小麦-水稻轮作平均GWP为2500 kg CO当量。 hap＃yrp＃。分析指出，有机会通过以下方式降低这些灌溉农业系统的全球升温潜能值：（i）优化施肥和灌溉方式;（ii）将年度种植系统转变为多年生人工林，特别是在利润较低的边缘土地上。

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