High soil nitrous oxide emissions from a greenhouse vegetable production system in Shouguang, Northern China

Abstract

In China, the area of greenhouse vegetable production (GVP) has exceeded 4 million ha, accounting for >80% of global GVP systems. Excessive nitrogen (N) fertilization and frequent irrigation have created GVP hotspots of nitrous oxide (N2O) emissions. There are several studies on soil N2O emissions from GVP systems, but all with low-frequency manual sampling, which may have resulted in large uncertainties regarding quantifying N2O emissions. Herein, we utilized an automatic chamber system equipped with 16 channels to measure N2O emissions under common farm practice from a GVP system in Shouguang, Northern China. We measured emissions from both furrows and ridges for 1 year from July 2020 to July 2021. Our continuous monitoring showed that the annual soil N2O emission was 102 kg N ha−1, accounting for 7.6% of the applied N (1338 kg N ha−1). The annual N2O emission from furrows (176 kg N ha−1) was significantly higher than that from ridges (28 kg N ha−1). Large spatial variations in the N2O emissions were observed, ranging from 102 to 273 kg N ha−1 yr−1 for furrows (n = 8) and from 19 to 45 kg N ha−1 yr−1 for ridges (n = 7). In addition, we found that irrigation caused N2O flux pulses from furrows, increasing by 12–396% compared with the level before irrigation. High-frequency measurements using our automatic chamber system provided detailed information on the diurnal and seasonal dynamics of N2O emissions, which could be useful for building more accurate models and developing more effective policies to reduce N2O emissions from global GVP systems.