Alternate wetting and drying of rice reduced CH4 emissions but triggered N2O peaks in a clayey soil of central Italy

Authors: LAGOMARSINO, ALESSANDRA - Consiglio Per La Ricerca In Agricoltura E L'Analisi Dell'economia Agraria, Unita Di Ricerca Per I S; AGNELLI ELIO, ALESSANDRO - Consiglio Per La Ricerca In Agricoltura E L'Analisi Dell'economia Agraria, Unita Di Ricerca Per I S; FERRARA, ROSSANA MONICA - Consiglio Per La Ricerca In Agricoltura E L'Analisi Dell'economia Agraria, Unita Di Ricerca Per I S; Adviento-Borbe, Arlene; LINQUIST, BRUCE - University Of California; GAVINA, GIACOMO - Sis Società Italiana Sementi Spa Via Mirandola, Italy; RAVAGLIA, STEFANO - Sis Società Italiana Sementi Spa Via Mirandola, Italy

Submitted to: Pedosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2016
Publication Date: 4/26/2016
Publication URL: http://handle.nal.usda.gov/10113/62642
Citation: Lagomarsino, A., Agnelli Elio, A., Ferrara, R., Adviento-Borbe, A.A., Linquist, B., Gavina, G., Ravaglia, S. 2016. Alternate wetting and drying of rice reduced CH4 emissions but triggered N2O peaks in a clayey soil of central Italy. Pedosphere. 26(4):533–548.

Interpretive Summary: Rice cropping system contributes significantly to greenhouse gas (GHG) emissions mainly through CH4 and N2O missions. Irrigated rice is unique from most other crops because it is grown under flooded conditions where waterlogged condition favors CH4 production, and rice plants serve as pathways for gas release to the environment. Given that CH4 and N2O are greatly released from rice fields there is a great opportunity to mitigate these GHG gases through water management strategies without yield decline. Alternate wetting & drying (AWD) irrigation practice can reduce GHG emissions from continuous flooding to intermittent flooding by introducing periodically aerobic condition during the growing season. While draining rice fields minimizes CH4 emissions, aerobic condition stimulates N2O emissions. The implementation of AWD in rice cultivation decreased substantially CH4 emissions and irrigation water use however, the exposure of rice fields to drained conditions increased even more the emission of N2O. Grain yields were also reduced under AWD irrigation practice. Under water-saving practice it is critical to managed both the reduction of CH4 and N2O emissions while sustaining grain yield to be able to achieve the multiple benefits of this technology. This information will help rice growers and extension workers to carefully design and managed irrigation water management practice that minimizes the use of surface water and emissions of CH4 and N2O while sustaining the economic performance of rice growers.

Technical Abstract: Reducing CH4 and N2O emissions from rice cropping systems while sustaining production levels with less water requires a better understanding of the key processes involved. Alternate wetting and drying (AWD) irrigation is one promising practice that has been shown to reduce CH4 emissions. However, little is known about the impact of this practice on N2O emissions in particular under Mediterranean climate. To close this knowledge gap, we assessed how AWD influenced grain yield, fluxes and annual budgets of CH4 and N2O emissions, and global warming potential (GWP) in Italian rice systems over a two year period. Overall, a larger GWP was observed under AWD, as result of high N2O emissions which offset reductions in CH4 emissions. In the first year, with 70% water reduction, the yields were reduced by 33%, CH4 emissions decreased by 97% and N2O emissions were more than six-fold greater. In the second year, the less severe with a 40% water-saving rice yields and CH4 reduction (13 and 11% respectively) were not significant but N2O fluxes were more than doubled. The transition from anaerobic to aerobic soil conditions resulted in the highest N2O fluxes under AWD.