Pathways of nitrogen loss and optimized nitrogen management for a rice cropping system in arid irrigation region, northwest China
Pathways of nitrogen loss and optimized nitrogen management for a rice cropping system in arid irrigation region, northwest China
复制标题
西北旱灌区水稻种植体系氮素流失途径及氮素优化管理
DOI：
10.1016/j.jenvman.2020.110702
复制
发表时间：
2020
影响因子：
8.7
通讯作者：
Zhengli Yang
中科院分区：
文献类型：
--
作者：
Xiaoying Zhan;Qingwen Zhang;Hui Zhang;Hafiz Athar Hussain;Muhammad Shaaban;Zhengli Yang
由于气候类型和作物管理的不同，干旱地区水稻种植系统的活性氮（N）损失表现出与亚热带湿润地区不同的模式。然而，这一地区却很少受到关注。为了填补这一知识空白，我们在中国西北部的宁夏灌区进行了为期两年（2009-2010）的实地观察，以探索当地农民最佳实践后氮素流失的主要途径。此外，我们还确定了氨氮和一氧化二氮的特定地点排放因子、地表径流和地下（淋溶和渗流）速率，以提高干旱灌区的清单分辨率。结果表明，氨挥发（占氮素损失总量的45%～49%）、淋溶和渗漏（占氮素损失总量的30%～33%）被证明是稻田氮素损失的主要因素。农户实践得出的氨排放因子（21%）和氮淋失率（7.5%）分别比我国国家默认值高2.1和5.4倍。该地区可直接采用各国具体的N径流率和N2O排放因子。农民实践中氮肥用量减少 20%（300 kg N ha−1）并施用有机肥（合成肥料中的 30% 氮被猪粪替代）被认为是该地区的最佳施氮量。我们的研究可以缩小干旱地区和亚热带湿润地区氮素流失研究之间的差距。同时，研究结果可为干旱灌区的政策制定者提供减缓氮素损失的具体建议。
The reactive nitrogen (N) loss of the rice cropping system in the arid region shows a different pattern from that of subtropical humid region due to different climate types and crop management. However, little attention has been paid to this region. To fill this knowledge gap, a two-year (2009–2010) field observation was conducted in the Ningxia irrigation region, northwest China, to explore the major pathway of N loss following local farmers' optimal practice. Further, we determined the site-specific emission factors of ammonia and nitrous oxide, rate of surface runoff and subsurface (leaching and seepage) to improve the inventory resolution of arid irrigation region. Results showed that ammonia volatilization (45%–49% of total N loss), leaching and seepage (30%–33% of total N loss) were proved to be the primary factors of N loss in rice paddy fields. The emission factor of ammonia (21%) and N leaching rate (7.5%) following farmers' practice were 2.1 and 5.4 times higher than the country-specific default value in China. The country-specific N runoff rate and emission factor of N2O could be directly adopted in this region. A 20% reduction of N fertilizer to farmers’ practice (300 kg N ha−1) alongside the application of organic fertilizer (30% N in synthetic fertilizer was substituted by pig manure) were considered to be the optimal N rate in this region. Our study can narrow the gap between researches on N loss in arid regions and subtropical humid regions. Meanwhile, the results can provide specific advice on N loss mitigation for policy makers in arid irrigation regions.