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Optimal Fertilizer Nitrogen Rates and Yield‐Scaled Global Warming Potential in Drill Seeded Rice
Author(s) -
AdvientoBorbe Maria Arlene,
Pittelkow Cameron M.,
Anders Merle,
Kessel Chris,
Hill James E.,
McClung Anna M.,
Six Johan,
Linquist Bruce A.
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2013.05.0167
Subject(s) - environmental science , fertilizer , growing season , agronomy , greenhouse gas , tonne , global warming potential , global warming , paddy field , zoology , climate change , ecology , chemistry , biology , organic chemistry
Drill seeded rice ( Oryza sativa L.) is the dominant rice cultivation practice in the United States. Although drill seeded systems can lead to significant CH 4 and N 2 O emissions due to anaerobic and aerobic soil conditions, the relationship between high‐yielding management practices, particularly fertilizer N management, and total global warming potential (GWP) remains unclear. We conducted three field experiments in California and Arkansas to test the hypothesis that by optimizing grain yield through N management, the lowest yield‐scaled global warming potential (GWP Y = GWP Mg −1 grain) is achieved. Each growing season, urea was applied at rates ranging from 0 to 224 kg N ha −1 before the permanent flood. Emissions of CH 4 and N 2 O were measured daily to weekly during growing seasons and fallow periods. Annual CH 4 emissions ranged from 9.3 to 193 kg CH 4 –C ha −1 yr −1 across sites, and annual N 2 O emissions averaged 1.3 kg N 2 O–N ha −1 yr −1 . Relative to N 2 O emissions, CH 4 dominated growing season (82%) and annual (68%) GWP. The impacts of fertilizer N rates on GHG fluxes were confined to the growing season, with increasing N rate having little effect on CH 4 emissions but contributing to greater N 2 O emissions during nonflooded periods. The fallow period contributed between 7 and 39% of annual GWP across sites years. This finding illustrates the need to include fallow period measurements in annual emissions estimates. Growing season GWP Y ranged from 130 to 686 kg CO 2 eq Mg −1 season −1 across sites and years. Fertilizer N rate had no significant effect on GWP Y ; therefore, achieving the highest productivity is not at the cost of higher GWP Y .