Effects of controlled irrigation on global warming potential based on CH4, N2O and CO2 fluxes in plateau paddy field

Abstract

A suitable irrigation pattern is of great significance for reducing greenhouse gas emissions. In this study, field experiments and a denitrification-decomposition (DNDC) model were used to study the global warming potential based on CH₄, N₂O and CO₂ fluxes under flooding irrigation and controlled irrigation in paddy fields in the Erhai Lake basin. The results showed that the average value of CH₄ flux under controlled irrigation was lower than that under flooding irrigation, with a reduction range of 43.21% to 48.88%, however, the average value of the N₂O and CO₂ fluxes from paddy field under controlled irrigation were higher than those under flooding irrigation. Controlled irrigation patterns can significantly reduce the global warming potential in paddy fields based on CH₄, N₂O and CO₂ fluxes. Controlled irrigation can effectively reduce the global warming potential per unit yield. For water management in the Erhai Lake basin, it is recommended the controlled irrigation treatment of soil moisture with an upper limit of 100% and a lower limit of 75–85% with irrigation, and a maximum surface water depth of 150–200 mm lasting for five days after precipitation from the jointing-booting stage to the milk stage.