High nitrous oxide fluxes from rice indicate the need to manage water for both long- and short-term climate impacts

Abstract

Significance Methane from global rice cultivation currently accounts for one-half of all crop-related greenhouse gas emissions. Several international organizations are advocating reductions in methane emissions from rice by promoting intermittent flooding without accounting for the possibility of large emissions of nitrous oxide (N 2 O), a long-lived greenhouse gas. Our experimental results suggest that the Indian subcontinent’s N 2 O emissions from intermittently flooded rice fields could be 30–45 times higher than reported under continuous flooding. Net climate impacts of rice cultivation could be reduced by up to 90% through comanagement of water, nitrogen, and carbon. To do this effectively will require a careful ongoing global assessment of N 2 O emissions from rice, or we will risk ignoring a very large source of climate impact.