Impacts of long-term nitrogen addition on nitrous oxide in a temperate grassland

¹ Lanzhou City University, Lanzhou 730070, China.
² School of Biological and Environmental Engineering, Xi’an University, Xi’an 710065, China
³ Engineering Center for Pollution Control and Ecological Restoration in Mining of Gansu Province, Lanzhou City University, Lanzhou 730070, China
⁴ Key Laboratory of Plant-Soil Interactions of MOE and Beijing Key Laboratory of Farmland Pollution Prevention and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
⁵ Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China

^* Corresponding author: Xuejun Liu, Emil: liu310@cau.edu.cn

Abstract

Atmospheric nitrogen (N) deposition has increased dramatically due to increased human activities since the industrial revolution. However, it is still unclear what the responses of soil nitrous oxide (N₂O) is to long-term elevated N deposition in a temperate grassland. Here, we conducted an in situ field experiment to investigate these responses to long-term high N addition on a temperate steppe in Inner Mongolia, China, from April 2017 to October 2018. Soil N₂O emissions significantly increased by long-term N addition, use of structural equation modeling (SEM) showed that topsoil (0-5 cm) NH₄⁺-N content was the most important limiting factor for N₂O emission. Our results indicate that long-term high N addition showed a significantly increase in N₂O emission in this temperate grassland.