Comparison of N2O Emissions From Cold Waterlogged and Normal Paddy Fields

Xiangyu Xu,Yousheng Xiong,Muhammad Shaaban,Minmin Zhang,Jiafu Yuan,Ronggui Hu

doi:10.3389/fenvs.2021.660133

Abstract

Paddy fields are major sources of atmospheric N2O. Soil temperature and moisture strongly affect N2O emissions from rice fields. However, N2O emissions from cold-waterlogged paddy fields (CW), an important kind of paddy soil in China, are not well studied so far. It is unclear whether the N2O emissions from cold-waterlogged paddy fields are the same as normal paddy fields (NW). We investigated the N2O emission characteristics from the CW and NW paddy fields under with (R1) and without (R0) rice in Tuku Village, Baisha Town, Yangxin County (YX site, monitoring in 2013) and Huandiqiao Town, Daye City (DY site, monitoring in 2014); compared the difference and influencing factors between the CW and NW paddy fields at two sites in South China. The results showed that the N2O emissions from NWR0 were 13.4 times higher than from CWR0, and from NWR1 were 10.3 times higher than from CWR1 in the YX site. The N2O emissions from NWR0 were 2.4 times higher than from CWR0, and from NWR1 were 17.3 times higher than from CWR1 in the DY site. The structural equation models (SEMs) showed that the N2O emissions are mainly driven by rice planting and soil moisture in the NW fields at the annual scale, while soil temperature in the CW fields. Overall, N2O emissions from cold waterlogged paddy fields are significantly lower than those of normal paddy fields due to the low temperature and higher water content; however, there are dinitrogen emissions from cold waterlogged paddy fields denitrification should be further examined.

Highlights

Nitrous oxide (N2O) is the third-largest long-lived greenhouse gas following CO2 and CH4
Regardless of rice planting, the mean soil water content of coldwaterlogged paddy fields (CW) fields was significantly higher than that of NW fields during the monitoring period (Figure 1, p < 0.01), and rice planting has no difference at both types of fields at two sites
The results showed that the N2O cumulative emissions from the CWR1 treatment were the lowest at both sites

Summary

Introduction

Nitrous oxide (N2O) is the third-largest long-lived greenhouse gas following CO2 and CH4. Its main characteristics are higher groundwater levels and lower soil temperature than normal paddy fields (Qiu et al, 2013; Liu et al, 2016). Those environments make strong anaerobic conditions, poor soil structure, high organic matter contents, and low rates of N mineralization (Xie et al, 2015). Those properties of CW fields result in significantly lower rice biomass yields and higher methane emissions than normal paddy fields (NW fields) (Xu et al, 2020)

Methods

Results

Discussion

Conclusion