New Records of Very High Nitrous Oxide Fluxes from Rice Cannot be Generalized for Water Management and Climate Impacts

This letter responds to a recent article in PNAS by Kritee et al. (2018) reporting very high nitrous oxide (N2O) emissions from rice fields in South India. While the observed N2O emissions from these fields are significant and call for attention to farming practices related to water management and nitrogen fertilizer application, this response highlights several critical concerns. First, it questions the experimental design, emphasizing the absence of a control treatment with continuous flooding and the use of non-standard treatments. Second, it challenges the assertion that previous studies missed high N2O emissions due to inadequate sampling frequency, pointing to existing studies with high-frequency and automated measurements. Third, it raises concerns about interpolation errors in the data and the need for model validation. Finally, it calls for caution in interpreting the risk of underestimating N2O emissions without assessing the likelihood of such risks. The authors argue that these individual field records of high emissions may also be statistical outliers. This response underscores the importance of rigorous research and data analysis when concluding N2O emissions from rice fields.
Nitrous oxide, Water management
Wassman, R., B.O. Sander, S. Yadav, B. Bouman, G. Singleton, A. Stuart, J. Hellin, D. Johnson, J. Hughes, K. Butterbach-Bahl, R. Kiese, D. Kraus, B. Janz, B. Linquist, Y.K. Gaihre, N. Chirinda, and E. Wollenberg. 2019. “New Records of Very High Nitrous Oxide Fluxes from Rice Cannot Be Generalized for Water Management and Climate Impacts,” PNAS, 116(5):1464-1465.