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ARS Home » Southeast Area » Jonesboro, Arkansas » Delta Water Management Research » Research » Publications at this Location » Publication #374045
Title: Assessing seasonal methane and nitrous oxide emissions from furrow irrigated rice with cover crops

Author
item KARKI, SANDHYA - University Of Arkansas
item Adviento-Borbe, Arlene
item Massey, Joseph
item Reba, Michele

Submitted to: Agriculture Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2021
Publication Date: 3/19/2021
Citation: Karki, S., Adviento-Borbe, A.A., Massey, J., Reba, M.L. 2021. Assessing seasonal methane and nitrous oxide emissions from furrow irrigated rice with cover crops. Popular Publication. 11,261;1-15. https://doi.org/10.3390/agriculture11030261.
DOI: https://doi.org/10.3390/agriculture11030261

Interpretive Summary: Row rice or furrow rice cropping entails a new water management practice in fields that have been bedded before rice planting or in fields that have existing beds from a previous soybean or corn crop. This method is becoming popular to rice growers in the Mississippi River Delta because it does not maintain a constant flood, reduces field operations, reduces methane emissions, and facilitates harvest. However, row rice may provide a potential risk to yield performance and fertilizer nitrogen loss through emissions of nitrous oxide. Our results show grain yields were the same between row rice and conventional flooded rice. However, implementation of cover cropping in row rice reduced grain yield by 29%. While methane emissions were reduced by 77 to 95% in row rice, nitrous oxide emissions increased by 25 fold when compared to conventional flooded rice. The decreased in methane emissions was offset by an increase in nitrous oxide emissions, hence there was no net benefit in greenhouse gas (GHG) emissions from row rice as compared to conventional flooded rice. Row rice or furrow irrigated rice is new and further studies focusing on water and fertilizer N management to reduce nitrous oxide emissions are needed to increase water and N use efficiencies with minimal or zero impact on producers’ economic returns. This information will benefit crop consultants, rice researchers, national and international scientific working groups on GHG inventories and importantly rice growers on trading of carbon emissions to Carbon Credit Marketplace.

Technical Abstract: Improved irrigation management is identified as a potential mitigation option for CH4 emissions from rice (Oryza sativa). Furrow irrigated rice (FR), an alternative method to grow rice with less water, is increasingly adopted in the Mid-South US. However, FR may provide a potential risk to yield performance and fertilizer nitrogen loss through emissions of nitrous oxide (N2O). This study quantified the grain yields, CH4 and N2O emissions from three different water management practices in rice; multiple inlet rice irrigation (MIRI), FR, and FR with cereal rye as preceding winter cover crops (FRCC). FR and FRCC fields were further divided into top and bottom paddies due to variation in soil moisture across the field for the quantification of grain yields and greenhouse gas (GHG) flux measurement. Gas fluxes of CH4 and N2O were measured from May to September 2019 using a static chamber technique and analyzed with gas chromatography. There was no difference in harvested grain yield from top and bottom paddies except from FR where the grain yield was lower from top paddies. The grain yield from FR (11.8 Mg ha-1) and MIRI (12.0 Mg ha-1) was similar, and significantly higher than FRCC (8.5 Mg ha-1). FR and FRCC drastically reduced CH4 emissions compared to MIRI with highest reduction from top paddies. Combining both the top and bottom paddies emissions from FR and FRCC, total seasonal CH4 emissions decreased in the order of 60 >14 >3 kg CH4-C ha-1 from MIRI, FR, and FRCC, respectively. Cumulative seasonal N2O emissions were low from MIRI (0.2 kg N2O-N ha-1) but significantly higher from FR (4.8 kg N2O-N ha-1) and FRCC (5.0 kg N2O-N ha-1). In conclusion, there was no net benefit in global warming potential from FR and FRCC as compared to MIRI.