Changes in Ammonia-Oxidizing Archaea and Bacterial Communities and Soil Nitrogen Dynamics in Response to Long-Term Nitrogen Fertilization.

Aixia Xu,Subramaniam Gopalakrishnan,Sumera Anwar,Linlin Wang,Yuji Jiang,Chang Liu,Lingling Li,Renzhi Zhang,Liqun Cai,Zhuzhu Luo,Junhong Xie

doi:10.3390/ijerph19052732

Abstract

Ammonia oxidizing archaea (AOA) and bacteria (AOB) mediate a crucial step in nitrogen (N) metabolism. The effect of N fertilizer rates on AOA and AOB communities is less studied in the wheat-fallow system from semi-arid areas. Based on a 17-year wheat field experiment, we explored the effect of five N fertilizer rates (0, 52.5, 105, 157.5, and 210 kg ha−1 yr−1) on the AOA and AOB community composition. This study showed that the grain yield of wheat reached the maximum at 105 kg N ha−1 (49% higher than control), and no further significant increase was observed at higher N rates. With the increase of N, AOA abundance decreased in a regular trend from 4.88 × 107 to 1.05 × 107 copies g−1 dry soil, while AOB abundance increased from 3.63 × 107 up to a maximum of 8.24 × 107 copies g−1 dry soil with the N105 treatment (105 kg N ha−1 yr−1). Application rates of N fertilizer had a more significant impact on the AOB diversity than on AOA diversity, and the highest AOB diversity was found under the N105 treatment in this weak alkaline soil. The predominant phyla of AOA and AOB were Thaumarchaeota and Proteobacteria, respectively, and higher N treatment (N210) resulted in a significant decrease in the relative abundance of genus Nitrosospira. In addition, AOA and AOB communities were significantly associated with grain yield of wheat, soil potential nitrification activity (PNA), and some soil physicochemical parameters such as pH, NH4-N, and NO3-N. Among them, soil moisture was the most influential edaphic factor for structuring the AOA community and NH4-N for the AOB community. Overall, 105 kg N ha−1 yr−1 was optimum for the AOB community and wheat yield in the semi-arid area.

Highlights

IntroductionNitrification is the most crucial step in the biogeochemical nitrogen (N) cycle in which
Nitrification is the most crucial step in the biogeochemical nitrogen (N) cycle in whichNH3 is oxidized to NO2 − and to NO3 − [1–3]
This study showed that Ammonia oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities responded differentially to N fertilizer application rates (Figure 1)

Summary

Introduction

Nitrification is the most crucial step in the biogeochemical nitrogen (N) cycle in which. NH3 is oxidized to NO2 − and to NO3 − [1–3]. The nitrification process regulates the absorption and availability of N to crops in the soil ecosystem [4,5] and may cause the loss of N because leaching of NO3 − is much easier than NH3 [6]. Ammonia oxidizing archaea (AOA) and bacteria (AOB) mediate a very critical step in nitrogen (N) metabolism [7,8]. Both AOA and AOB contain the gene encoding the ammonia monooxygenase amoA, which.

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Discussion

Conclusion