A 3-year field measurement of methane and nitrous oxide emissions from rice paddies in China : Effects of water regime, crop residue, and fertilizer application

TLDR: In this paper, a 3-year field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions from rice paddies under various agricultural managements including water regime, crop residue incorporation, and synthetic fertilizer application.

Abstract: [1] A 3-year field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions from rice paddies under various agricultural managements including water regime, crop residue incorporation, and synthetic fertilizer application In contrast with continuous flooding, midseason drainage incurred a drop in CH4 fluxes while triggering substantial N2O emission Moreover, N2O emissions after midseason drainage depended strongly on whether or not fields were waterlogged due to intermittent irrigation Urea application tended to reduce CH4 emissions but significantly increased N2O emissions Under a water regime of flooding-midseason drainage-reflooding-moist intermittent irrigation but without water logging (F-D-F-M), both wheat straw and rapeseed cake incorporation increased CH4 emissions by 252%, and rapeseed cake increased N2O by 17% while wheat straw reduced N2O by 19% compared to controls Seasonal average fluxes of CH4 ranged from 254 mg m−2 d−1 when no additional residue was applied under the water regime of flooding-midseason drainage-reflooding to 1169 mg m−2 d−1 when wheat straw was applied at 225 t ha−1 under continuous irrigation flooding Seasonal average fluxes of N2O varied between 003 mg N2O-N m−2 d−1 under continuous flooding and 523 mg N2O-N m−2 d−1 under the water regime of F-D-F-M Both crop residue-induced CH4, ranging from 9 to 15% of the incorporated residue C, and N2O, ranging from 001 to 178% of the applied N, were dependent on water regime in rice paddies Estimations of net global warming potentials (GWPs) indicate that water management by flooding with midseason drainage and frequent water logging without the use of organic amendments is an effective option for mitigating the combined climatic impacts from CH4 and N2O in paddy rice production