241-3 Water Management Affected GHG Emissions and Microbial Community Pattern in a Clayey Soil of Central Italy.

See more from this Division: SSSA Division: Soil and Water Management and Conservation
See more from this Session: Greenhouse Gas Emissions and Migitation from Lands Oral (includes student competition)

Tuesday, November 8, 2016: 10:45 AM
Phoenix Convention Center North, Room 128 B

Alessandra Lagomarsino1, Alessandro Elio Agnelli2, Bruce Linquist3, Arlene Adviento-Borbe4, Rossana Monica Ferrara5, Roberta Pastorelli2, Grazia Pallara6, Daniel P. Rasse7 and Hanna Silvennoinen8, (1)CREA-ABP, Firenze, ITALY
(2)CREA-ABP, Firenze, Italy
(3)Department of Plant Sciences, University of California, Davis, Davis, CA
(4)Delta Water Management Research Unit, USDA ARS, Jonesboro, AR
(5)CREA-SCA, Bari, Italy
(6)University of Firenze, Firenze, Italy
(7)Soil Quality and Climate Change, Norwegian Institute of Bioeconomy Research - NIBIO, Aas, NORWAY
(8)NIBIO, Aas, NORWAY
Abstract:
Reducing CH4 and N2O emissions from rice cropping systems while sustaining productivity with less irrigation water requires a better understanding of the key processes involved. Also, the role of microbial communities driving CH4 and N2O production in soils under different management is still unclear. To close this knowledge gap, we assessed how alternate wetting and drying (AWD) irrigation practice influenced fluxes and annual budgets of CH4 and N2O emissions in Italian rice systems in a field trial over a 2-year period and the influence of water management on microbial community structure and adaptation in a laboratory experiment.

Overall, a larger global warming potential (GWP) was observed under AWD, as a result of huge N2O peaks which offset reductions in CH4 emissions. This trend was more evident with harsher water reduction, in fact the transition from anaerobic to aerobic soil conditions resulted in the highest N2O fluxes under AWD. The water management strongly affected microbial community structure also, which was itself tightly linked to CH4 and N2O production. N2O production was the highest in aerobic soil, which also exhibited the strongest evidence for active nitrifying communities (NirK). Drying and rewetting aerobic soil enhanced the production of nitrate, which was further reduced to N2O through incomplete denitrification. As expected, CH4 production was the lowest in aerobic soil, which showed a less abundant archaeal community.

The duration of flooding, transition to aerobic conditions, water level above the soil surface, and the relative timing between fertilization and flooding were the main drivers affecting GHG mitigation potential under AWD and should be carefully planned through site-specific management options. Microbial communities in paddy soils progressively adapt to water management practices, thereby reinforcing potential differences in GHGs production.

See more from this Division: SSSA Division: Soil and Water Management and Conservation
See more from this Session: Greenhouse Gas Emissions and Migitation from Lands Oral (includes student competition)