Field Validation of the DNDC-Rice Model for Methane and Nitrous Oxide Emissions from Double-Cropping Paddy Rice under Different Irrigation Practices in Tamil Nadu, India

Akinori Yamamoto,Aung Zaw Oo,Khin Thuzar Win,Vellaisamy Ambethgar,Keisuke Ono,Shigeto Sudo,Chellappan Umamageswari,Kaliappan Sathiya Bama,Tamon Fumoto,Marimuthj Raju,Kazuyuki Inubushi,Sonoko D Bellingrath-Kimura,Venkatachalam Ravi,Palanisamy Elayakumar,Koothan Vanitha

doi:10.3390/agriculture10080355

Abstract

Two-year field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu, India, to evaluate the effect of continuous flooding (CF) and alternate wetting and drying (AWD) irrigation strategies on rice grain yield and greenhouse gas emissions from double-cropping paddy rice. Field observation results showed that AWD irrigation was found to reduce the total seasonal methane (CH4) emission by 22.3% to 56.2% compared with CF while maintaining rice yield. By using the observed two-year field data, validation of the DNDC-Rice model was conducted for CF and AWD practices. The model overestimated rice grain yield by 24% and 29% in CF and AWD, respectively, averaged over the rice-growing seasons compared to observed values. The simulated seasonal CH4 emissions for CF were 6.4% lower and 4.2% higher than observed values and for AWD were 9.3% and 12.7% lower in the summer and monsoon season, respectively. The relative deviation of simulated seasonal nitrous oxide (N2O) emissions from observed emissions in CF were 27% and −35% and in AWD were 267% and 234% in the summer and monsoon season, respectively. Although the DNDC-Rice model reasonably estimated the total CH4 emission in CF and reproduced the mitigation effect of AWD treatment on CH4 emissions well, the model did not adequately predict the total N2O emission under water-saving irrigation. In terms of global warming potential (GWP), nevertheless there was a good agreement between the simulated and observed values for both CF and AWD irrigations due to smaller contributions of N2O to the GWP compared with that of CH4. This study showed that the DNDC-Rice model could be used for the estimation of CH4 emissions, the primary source of GWP from double-cropping paddy rice under different water management conditions in the tropical regions.

Highlights

Rice cultivation is a major source of atmospheric methane (CH4 ), one of the significant potent greenhouse gases (GHG) and is responsible for approximately 11% of global anthropogenic CH4 emissions [1]
The results showed that water-saving irrigation is feasible in double-cropping paddy rice in the tropical region without affecting rice grain yield
Beside the limited data availability, the major objective of this study was to validate the DNDC-Rice model in predicting CH4 and nitrous oxide (N2 O) emissions under different irrigation practices

Summary

Introduction

Rice cultivation is a major source of atmospheric methane (CH4 ), one of the significant potent greenhouse gases (GHG) and is responsible for approximately 11% of global anthropogenic CH4 emissions [1]. Conventional management practices of continuously flooded irrigation in paddy fields enhance anaerobic fermentation of carbon sources supplied by the rice plants and added organic matter and results in high CH4 production. Midseason drainage and alternate wetting and drying irrigation (AWD) practice have been promoted as a strategy to decrease CH4 emissions from paddy rice fields [3,5,6,7,8]. It can result in increased N2 O emissions due to a trade-off between CH4 and N2 O [2,3,9]. Frequent alternations in soil redox conditions under water saving irrigation are known to substantially increase

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Conclusion