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Ammonia fluxes and emission factors under an intensively managed wetland rice ecosystem
Environmental Science: Processes & Impacts ( IF 5.5 ) Pub Date : 2020-12-10 , DOI: 10.1039/d0em00374c
S. Uddin 1, 2, 3, 4 , T. T. Nitu 1, 2, 3, 4 , U. M. Milu 1, 2, 3, 4 , S. S. Nasreen 1, 2, 3, 4 , M. Hossenuzzaman 1, 2, 3, 4 , M. E. Haque 4, 5, 6, 7 , B. Hossain 4, 8, 9 , M. Jahiruddin 1, 2, 3, 4 , R. W. Bell 6, 10, 11, 12, 13 , C. Müller 14, 15, 16, 17, 18 , M. M. R. Jahangir 1, 2, 3, 4
Affiliation  

Nitrogen (N) loss from rice production systems in the form of ammonia (NH3) can be a significant N loss pathway causing significant economic and environmental costs. Yet, data on NH3 fluxes in wetland rice ecosystems are still very scarce which limits the accuracy of national and global NH3 budgets. We measured the NH3 fluxes in situ in a wetland rice field and estimated emission factors (EF) under two soil management systems (i.e. conventional tillage, CT and strip tillage, ST); two residue retention levels (i.e. 15%, LR and 40% crop residue by height, HR); and three N fertilization rates (i.e. 108, 144 and 180 kg N ha−1) in two consecutive years (2019 and 2020). The highest NH3 peaks were observed within the first 3 days after urea application. The mean and cumulative NH3 fluxes significantly increased with the increases in N fertilization rates and were 18.5% and 18.6% higher in ST than in CT in 2020 but not in 2019. Overall, the highest mean NH3 fluxes were in 180 kg N ha−1 coupled with either HR or LR and ST or CT. In 2019, the NH3 EF was unchanged by any treatments. In 2020, the lower EF was in CT coupled with LR (15%) than all other treatment combinations, where ST with HR showed the highest EF (20%). Likewise, the lowest N rate (108 kg N ha−1) in ST had the highest NH3 EF (20%) that was similar to higher N rates (144 and 180 kg N ha−1) in the same tillage treatment and to 180 kg N ha−1 in CT. Our results highlight that NH3 fluxes in rice field particularly the effects of ST correlated with higher soil pH and NH4+ content and lower redox potential. Our results highlight that NH3 fluxes are a potentially large N loss pathway in wetland rice under conventional and decreased soil disturbance regimes.

中文翻译:

集约化管理的湿地水稻生态系统下的氨通量和排放因子

稻米生产系统中以氨(NH 3)形式损失的氮(N)可能是一条重要的N损失途径,从而导致巨大的经济和环境成本。但是,关于湿地水稻生态系统中NH 3排放量的数据仍然非常稀少,这限制了国家和全球NH 3预算的准确性。我们测量了湿地稻田中的NH 3通量并在两种土壤管理系统(常规耕作,CT和剥离耕作,ST)下估算了排放因子(EF )。两个残留物保留水平(15%,LR和40%作物残留物的高度,HR);和三个氮肥施用量(108、144和180 kg N ha-1)连续两年(2019年和2020年)。在施用尿素后的前三天内观察到最高的NH 3峰。随着施氮量的增加,平均NH 3通量和累积通量显着增加,到2020年,ST比CT高出18.5%和18.6%,而在2019年则没有。总的来说,最高平均NH 3通量在180 kg N ha -1与HR或LR以及ST或CT耦合。在2019年,任何处理均未改变NH 3 EF。2020年,CT和LR结合使用的EF较低(15%),高于所有其他治疗组合,其中HR的ST表现出最高的EF(20%)。同样,ST中最低的N比率(108 kg N ha -1)具有最高的NH3 EF(20%),与相同耕作处理中较高的氮素含量(144和180 kg N ha -1)和CT中的180 kg N ha -1相似。我们的结果表明,稻田中的NH 3通量,特别是ST的影响与土壤pH和NH 4 +含量较高以及氧化还原电势较低相关。我们的结果表明,在常规和减少的土壤扰动情况下,湿地水稻中的NH 3通量可能是一个较大的氮素流失途径。
更新日期:2020-12-24
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