土壤氮(N)转化过程,包括反硝化,厌氧氨氧化(厌氧氨氧化),厌氧氨氧化与铁还原(Feammox),构成土壤二氮(N2)流失的主要机制。尽管这些过程的重要性,在评估管理施肥和灌溉对水稻土厌氧氮转化的影响方面,研究存在显著差距,对于实现可持续的土壤肥力管理至关重要。这项研究通过调查土壤反硝化的贡献来解决这一差距,anammox,和Feammox在不同土壤深度的稻田土壤中对N2的损失,通过利用N稳定同位素技术采用不同的施肥和灌溉方法,以获得全面的见解。结果表明,在干湿交替灌溉(AWD)下,厌氧N转化过程随土壤深度的增加而减少,但在常规连续洪水(CF)灌溉下,随着土壤深度的增加而增加。反硝化和厌氧氨氧化率分别在0.41至2.12mgNkg-1d-1和0.062-0.394mgNkg-1d-1之间变化,占土壤N2流失总量的84.3-88.1%和11.8-15.7%。反硝化率与厌氧氨氧化率呈显著相关(r=0.986,p<0.01),Fe(Ⅲ)还原速率和反硝化速率(r=0.527,p<0.05),铁(Ⅲ)还原率和厌氧氨氧化率(r=0.622,p<0.05)。此外,与深层相比,水稻土表层的氮素流失更为明显。研究表明,反硝化作用主要导致表层土壤中的氮流失,而Feammox在20到40厘米的深度范围内作为一个显著的N损失途径出现,占氮素损失的26.1%。结论是受精,灌溉,和土壤深度显著影响厌氧N转化过程。此外,CF灌溉实践是减少管理施肥下氮素损失的最佳选择。此外,微生物群落的作用及其对不同土壤深度的反应,施肥实践,灌溉方法可以增强我们对氮素流失途径的理解,应该在未来的研究中进行探索。
Soil nitrogen (N) transformation processes, encompassing
denitrification, anaerobic ammonium oxidation (anammox), and anaerobic ammonium oxidation coupled with iron reduction (Feammox), constitute the primary mechanisms of soil dinitrogen (N2) loss. Despite the significance of these processes, there is a notable gap in research regarding the assessment of managed fertilization and irrigation impacts on anaerobic N transformations in paddy soil, crucial for achieving sustainable soil fertility management. This
study addressed the gap by investigating the contributions of soil
denitrification, anammox, and Feammox to N2 loss in paddy soil across varying soil depths, employing different fertilization and irrigation practices by utilizing N stable isotope technique for comprehensive insights. The results showed that anaerobic N transformation processes decreased with increasing soil depth under alternate wetting and drying (AWD) irrigation, but increased with the increasing soil depth under conventional continuous flooding (CF) irrigation. The
denitrification and anammox rates varied from 0.41 to 2.12 mg N kg-1 d-1 and 0.062-0.394 mg N kg-1 d-1, respectively, which accounted for 84.3-88.1% and 11.8-15.7% of the total soil N2 loss. Significant correlations were found among denitrification rate and anammox rate (r = 0.986, p < 0.01), Fe (Ⅲ) reduction rate and denitrification rate (r = 0.527, p < 0.05), and Fe(Ⅲ) reduction rate and anammox rate (r = 0.622, p < 0.05). Moreover, nitrogen loss was more pronounced in the surface layer of the paddy soil compared to the deep layer. The
study revealed that
denitrification predominantly contributed to N loss in the surface soil, while Feammox emerged as a significant N loss pathway at depths ranging from 20 to 40 cm, accounting for up to 26.1% of the N loss. It was concluded that fertilization, irrigation, and soil depth significantly influenced anaerobic N transformation processes. In addition, the CF irrigation practice is best option to reduce N loss under managed fertilization. Furthermore, the role of microbial communities and their response to varying soil depths, fertilization practices, and irrigation methods could enhance our understanding on nitrogen loss pathways should be explored in future
study.