Methane emissions from a rice agroecosystem in South China: Effects of water regime, straw incorporation and nitrogen fertilizer

Abstract

To quantitatively assess the effects of agricultural practices on methane (CH 4 ) emissions from rice fields, a two-year (2005/2006) field experiment with 2 3 factorial designs was conducted to assess the effects of three driving factors on CH 4 emissions in South China: continuously flooded (W0) and midseason and final drainages (W2), straw (S1) and nitrogen fertilizer (N1) applications and their controls (S0, N0). Results showed that averaged across all the treatments about 75 % of the seasonal total CH 4 occurred between the rice transplanting and booting stage, while constituted only 33 % of the seasonal total rice biomass during the same period. Averaged across the treatments in 2006, CH 4 emissions were substantially decreased by mid-season drainage up to 60 % (15.6 vs. 39.0 g m -2 ). The decreased CH 4 emissions represented almost all of the decrease in the total global warming potentials. Without straw incorporation CH 4 emissions substantially decreased up to 59 % (15.9 vs. 38.7 g m -2 ). The stimulating effects of straw were significantly greater for W0 than W2 treatment, being also greater in the 2005 than in the 2006 season. A significant inter-annual difference in CH 4 emissions was found when averaged across straw incorporation and N fertilizer applications for the W2 treatment (42.8 and 15.4 g m -2 in 2005 and 2006, respectively). Moreover, N fertilization has no significant effect on CH 4 emissions in this study. Our results demonstrate that although straw effects varied greatly with specific management, both straw managements and water regimes are equally important driving factors and thus being the most promising measures attenuating CH 4 emissions while achieving sustainable rice production.

Global warming potential and greenhouse gas intensity in rice agriculture driven by high yields and nitrogen use efficiency

“…4), possibly because soil changes from flooded to drained conditions may have enhanced N 2 O release (Deng et al, 2012). Alternation of drainage and flooding may induce large amounts of N 2 O emissions, particularly in fertilized systems; this has commonly been shown in earlier studies (Wang et al, 2012;Xiong et al, 2007;Zou et al, 2005). The seasonal and annual rates of N 2 O emissions were significantly affected by the cultivation practices and years (Table 4).…”

“…Of the two crops, CH 4 and irrigation were important for rice, but less important for wheat, in which N 2 O losses were expected to have a higher weight (Table 2). Methane emissions, the most important component of GWP in this typical rice-wheat rotation system, could be further mitigated by some other strategies, such as reasonable irrigation (Zou et al, 2005;Wang et al, 2012). Although N fertilizer application increased SOC sequestration when it was applied with rapeseed cake manure, this benefit was consistently overshadowed, on a CO 2 equivalent basis, by the increases in CH 4 and N 2 O emissions (Table 6).…”

Managing Water and Soils to Achieve Adaptation and Reduce Methane Emissions and Arsenic Contamination in Asian Rice Production

“…Thus, modifying the irrigation strategy reduced seasonal methane emission by about 60%, while the incorporation of straw increased methane emission by 59%. The authors conclude that water management and straw incorporation are equally important factors in determining methane emissions from rice paddies [164].…”

“…Changes in soil and water management practices can substantially reduce methane emissions attributed to paddy rice production [164][165][166][167]). Among the major cereals, rice production generates higher methane emissions per hectare and per unit of yield than does the production of wheat or maize [168].…”

“…Wang et al [164] also examine the potential reduction in methane emissions when modifying the irrigation strategy, in an experimental setting in Nanjing, China. The authors compare emissions from continuously flooded fields (W0), with emissions from fields that are drained twice each season: once for nine days at mid-season, and again for two weeks before harvest (W2).…”