Abstract
Soil-emitted nitrous oxide (N2O) and nitric oxide (NO) in crop production are harmful nitrogen (N) emissions that may contribute both directly and indirectly to global warming. Application of nitrification inhibitors, such as dicyandiamide (DCD), and urea deep placement (UDP), are considered effective approaches to reduce these emissions. This study investigated the effects of DCD and UDP, compared to urea and potassium nitrate, on emissions, nitrogen use efficiency and grain yields under direct-seeded rice. High-frequency measurements of N2O and NO emissions were conducted using the automated closed chamber method throughout the crop-growing season and during the ratoon crop. Both UDP and DCD were effective in reducing N2O emissions by 95% and 73%, respectively. The highest emission factor (1.53% of applied N) was observed in urea, while the lowest was in UDP (0.08%). Emission peaks were mainly associated with fertilization events and appeared within one to two weeks of fertilization. Those emission peaks contributed to 65%–98% of the total seasonal emissions. Residual effects of fertilizer treatments on the N2O emissions from the ratoon crop were not significant; however, the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions. On the other hand, cumulative NO emissions were not significant in either the rice or ratoon crops. UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea. The results suggested that the use of DCD and UDP could mitigate N2O emissions and increase grain yields and nitrogen use efficiency under direct-seeded rice condition.
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Claims 15
Claim · model-written summary
UDP reduced N2O emissions by 95%.
- Taxon
- Rice
Oryza sativat0 - Treatment
- UDPe0
- Outcome
- N2O emissionse0
- Direction
- reducinge0
- Value
- 95%e0
- Comparator
- urea and potassium nitratee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both UDP and DCD were effective in reducing N2O emissions by 95% and 73%, respectively”
e1“compared to urea and potassium nitrate”
t0“Rice”
Claim · model-written summary
DCD reduced N2O emissions by 73%.
- Taxon
- RiceOryza sativat0
- Treatment
- DCDe0
- Outcome
- N2O emissionse0
- Direction
- reducinge0
- Value
- 73%e0
- Comparator
- urea and potassium nitratee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both UDP and DCD were effective in reducing N2O emissions by 95% and 73%, respectively”
e1“compared to urea and potassium nitrate”
t0“Rice”
Claim · model-written summary
Urea had the highest emission factor at 1.53% of applied N.
- Taxon
- RiceOryza sativat0
- Treatment
- ureae0
- Outcome
- emission factore0
- Direction
- higheste0
- Value
- 1.53% of applied Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest emission factor (1.53% of applied N) was observed in urea, while the lowest was in UDP (0.08%)”
t0“Rice”
Claim · model-written summary
UDP had the lowest emission factor at 0.08%.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest emission factor (1.53% of applied N) was observed in urea, while the lowest was in UDP (0.08%)”
t0“Rice”
Claim · model-written summary
Emission peaks were associated with fertilization and appeared within one to two weeks.
- Taxon
- RiceOryza sativat0
- Treatment
- fertilization eventse0
- Outcome
- Emission peakse0
- Qualifier
- within one to two weeks of fertilizatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Emission peaks were mainly associated with fertilization events and appeared within one to two weeks of fertilization”
t0“Rice”
Claim · model-written summary
Emission peaks contributed 65%–98% of seasonal emissions.
- Taxon
- RiceOryza sativat0
- Outcome
- total seasonal emissionse0
- Value
- 65%–98%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Those emission peaks contributed to 65%–98% of the total seasonal emissions”
t0“Rice”
Claim · model-written summary
Residual fertilizer treatment effects on ratoon crop N2O emissions were not significant.
- Taxon
- RiceOryza sativat0
- Treatment
- fertilizer treatmentse0
- Outcome
- N2O emissions from the ratoon crope0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Residual effects of fertilizer treatments on the N2O emissions from the ratoon crop were not significant”
t0“Rice”
Claim · model-written summary
Urea contributed 2% of total annual emissions in the ratoon crop.
- Taxon
- RiceOryza sativat0
- Organ / stage
- ratoon crope1
- Treatment
- urea treatmente0
- Outcome
- total annual emissionse0
- Value
- 2%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions”
e1“N2O emissions from the ratoon crop were not significant”
t0“Rice”
Claim · model-written summary
UDP contributed 44% of total annual emissions in the ratoon crop.
- Taxon
- RiceOryza sativat0
- Organ / stage
- ratoon crope1
- Treatment
- UDPe0
- Outcome
- total annual emissionse0
- Value
- 44%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the urea treatment contributed 2%, whereas UDP contributed to 44% of the total annual emissions”
e1“N2O emissions from the ratoon crop were not significant”
t0“Rice”
Claim · model-written summary
Cumulative NO emissions were not significant in rice or ratoon crops.
- Taxon
- riceOryza sativae0
- Outcome
- cumulative NO emissionse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cumulative NO emissions were not significant in either the rice or ratoon crops”
Claim · model-written summary
UDP increased grain yield by 16%–19% over urea.
- Taxon
- RiceOryza sativat0
- Treatment
- UDPe0
- Outcome
- grain yieldse0
- Direction
- increasede0
- Value
- 16%–19%e0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea”
t0“Rice”
Claim · model-written summary
DCD increased grain yield by 16%–19% over urea.
- Taxon
- RiceOryza sativat0
- Treatment
- DCDe0
- Outcome
- grain yieldse0
- Direction
- increasede0
- Value
- 16%–19%e0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea”
t0“Rice”
Claim · model-written summary
UDP increased nitrogen recovery efficiency by 30%–40% over urea.
- Taxon
- RiceOryza sativat0
- Treatment
- UDPe0
- Outcome
- N recovery efficiencye0
- Direction
- increasede0
- Value
- 30%–40%e0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea”
t0“Rice”
Claim · model-written summary
DCD increased nitrogen recovery efficiency by 30%–40% over urea.
- Taxon
- RiceOryza sativat0
- Treatment
- DCDe0
- Outcome
- N recovery efficiencye0
- Direction
- increasede0
- Value
- 30%–40%e0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UDP and DCD increased grain yields by 16%–19% and N recovery efficiency by 30%–40% over urea”
t0“Rice”
Claim · model-written summary
The authors suggest DCD and UDP to reduce N2O emissions and improve yield and nitrogen use efficiency.
- Taxon
- riceOryza sativae0
- Outcome
- use of DCD and UDPe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the use of DCD and UDP could mitigate N2O emissions and increase grain yields and nitrogen use efficiency under direct-seeded rice condition”
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