Abstract
Drill seeded rice ( L.) is the dominant rice cultivation practice in the United States. Although drill seeded systems can lead to significant CH and NO 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 = GWP Mg grain) is achieved. Each growing season, urea was applied at rates ranging from 0 to 224 kg N ha before the permanent flood. Emissions of CH and NO were measured daily to weekly during growing seasons and fallow periods. Annual CH emissions ranged from 9.3 to 193 kg CH-C ha yr across sites, and annual NO emissions averaged 1.3 kg NO-N ha yr. Relative to NO emissions, CH 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 emissions but contributing to greater NO 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 ranged from 130 to 686 kg CO eq Mg season across sites and years. Fertilizer N rate had no significant effect on GWP; therefore, achieving the highest productivity is not at the cost of higher GWP.
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Claims 12
Claim · model-written summary
Annual CH4 emissions in drill seeded rice ranged from 9.3 to 193 kg CH4-C ha-1 yr-1 across sites.
- Taxon
- rice
Oryza sativat0 - Outcome
- Annual CH emissionse1
- Value
- 9.3 to 193 kg CH-C ha yre1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e1“Annual CH emissions ranged from 9.3 to 193 kg CH-C ha yr across sites”
Claim · model-written summary
Annual NO emissions averaged 1.3 kg NO-N ha-1 yr-1.
- Taxon
- riceOryza sativat0
- Outcome
- annual NO emissionse2
- Value
- 1.3 kg NO-N ha yre2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e2“annual NO emissions averaged 1.3 kg NO-N ha yr”
Claim · model-written summary
CH4 dominated the growing-season GWP, at 82% relative to NO emissions.
- Taxon
- riceOryza sativat0
- Outcome
- CH dominated growing seasone3
- Value
- 82%e3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e3“Relative to NO emissions, CH dominated growing season (82%) and annual (68%) GWP”
Claim · model-written summary
CH4 dominated the annual GWP, at 68% relative to NO emissions.
- Taxon
- riceOryza sativat0
- Outcome
- CH dominatede3
- Value
- 68%e3
- Qualifier
- annuale3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e3“Relative to NO emissions, CH dominated growing season (82%) and annual (68%) GWP”
Claim · model-written summary
Increasing N rate had little effect on CH4 emissions in drill seeded rice.
- Taxon
- riceOryza sativat0
- Treatment
- increasing N ratee4
- Outcome
- CH emissionse4
- Direction
- no_changeinferrede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e4“increasing N rate having little effect on CH emissions but contributing to greater NO emissions during nonflooded periods”
Claim · model-written summary
Increasing N rate increased NO emissions during nonflooded periods in drill seeded rice.
- Taxon
- riceOryza sativat0
- Treatment
- increasing N ratee4
- Outcome
- NO emissions during nonflooded periodse4
- Direction
- greatere4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e4“increasing N rate having little effect on CH emissions but contributing to greater NO emissions during nonflooded periods”
Claim · model-written summary
The effects of fertilizer N rates on GHG fluxes were confined to the growing season.
- Taxon
- riceOryza sativat0
- Treatment
- fertilizer N ratese5
- Outcome
- GHG fluxese5
- Qualifier
- confined to the growing seasone5
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e5“The impacts of fertilizer N rates on GHG fluxes were confined to the growing season”
Claim · model-written summary
The fallow period contributed 7 to 39% of annual GWP across site-years.
- Taxon
- riceOryza sativat0
- Outcome
- annual GWPe6
- Value
- between 7 and 39%e6
- Qualifier
- fallow periode6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e6“The fallow period contributed between 7 and 39% of annual GWP across sites years”
Claim · model-written summary
Growing-season GWP ranged from 130 to 686 kg CO2 eq Mg-1 season-1 across sites and years.
- Taxon
- riceOryza sativat0
- Outcome
- Growing season GWPe7
- Value
- 130 to 686 kg CO eq Mg seasone7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e7“Growing season GWP ranged from 130 to 686 kg CO eq Mg season across sites and years”
Claim · model-written summary
Fertilizer N rate had no significant effect on GWP in drill seeded rice.
- Taxon
- riceOryza sativat0
- Treatment
- Fertilizer N ratee0
- Outcome
- GWPe0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e0“Fertilizer N rate had no significant effect on GWP”
Claim · model-written summary
The authors conclude that the highest productivity is not achieved at the cost of higher GWP.
- Taxon
- riceOryza sativat0
- Outcome
- achieving the highest productivity is not at the cost of higher GWPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e0“therefore, achieving the highest productivity is not at the cost of higher GWP”
Claim · model-written summary
The authors recommend including fallow period measurements in annual emissions estimates.
- Taxon
- riceOryza sativat0
- Outcome
- include fallow period measurements in annual emissions estimatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Drill Seeded Rice”
e0“This finding illustrates the need to include fallow period measurements in annual emissions estimates”
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See all 108 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.