Abstract
Controlled-release urea (CRU) is widely reported to supply crop nitrogen (N) demand with one basal application, thus effectively replacing split applications of urea without diminishing grain yield and N use efficiency (NUE). However, its use for replacement for high-yield split applications of urea (CK) for rice is untested. In addition, the degree to which greenhouse gas (GHG) emissions in rice systems are affected when CRU is substituted for CK remains unclear. During 2017 and 2018, we sampled plant growth and gas emissions in a rice paddy field treated with three CRU types (sulfur-coated urea [SCU], polymer-coated urea [PCU], and bulk blended CRU [BBU]) applied via two methods (surface broadcasting on the soil and subsurface banding at 5 cm depth), with CK as a control. The three CRUs led to different soil NH4+-N dynamics, and the N supply pattern under BBU was more beneficial for rice seedling establishment than under SCU and PCU, resulting in grain yield and NUE comparable to those under CK. CRU type showed no significant effect on either CH4 emissions or N2O emissions, and broadcast CRUs exhibited significantly higher total GHG emissions than CK. However, banded CRUs significantly reduced the total GHG emissions in comparison with broadcast CRUs, by 9.2% averaged across the two years. Reduced CH4 emissions, particularly during the period prior to the middle drainage, contributed largely to the GHG difference. With comparably high grain yield and low total GHG emissions, banded BBU showed a low yield-scaled GHG (GHG emissions divided by grain yield) comparable to that under CK in both years. Overall, our study suggested that N management synchronized with rice demand and contributing to a high NUE tended to minimize yield-scaled GHG. Broadcast CRU can hardly substitute for CK in terms of either grain yield or GHG emissions, but banded BBU is a promising N management strategy for sustaining rice production while minimizing environmental impacts.
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Claims 11
Claim · model-written summary
BBU supplied nitrogen more favorably for rice seedling establishment than SCU and PCU.
- Taxon
- rice
Oryza sativae0 - Treatment
- BBUe0
- Outcome
- rice seedling establishmente0
- Direction
- more beneficiale0
- Comparator
- SCU and PCUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the N supply pattern under BBU was more beneficial for rice seedling establishment than under SCU and PCU”
Claim · model-written summary
BBU produced grain yield comparable to CK.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulting in grain yield and NUE comparable to those under CK”
e1“the N supply pattern under BBU was more beneficial for rice seedling establishment than under SCU and PCU”
Claim · model-written summary
BBU produced NUE comparable to CK.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“resulting in grain yield and NUE comparable to those under CK”
e1“the N supply pattern under BBU was more beneficial for rice seedling establishment than under SCU and PCU”
Claim · model-written summary
CRU type had no significant effect on CH4 emissions.
- Taxon
- riceOryza sativat0
- Treatment
- CRU typee0
- Outcome
- CH4 emissionse0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CRU type showed no significant effect on either CH4 emissions or N2O emissions”
t0“rice”
Claim · model-written summary
CRU type had no significant effect on N2O emissions.
- Taxon
- riceOryza sativat0
- Treatment
- CRU typee0
- Outcome
- N2O emissionse0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CRU type showed no significant effect on either CH4 emissions or N2O emissions”
t0“rice”
Claim · model-written summary
Broadcast CRUs produced significantly higher total GHG emissions than CK.
- Taxon
- riceOryza sativat0
- Treatment
- broadcast CRUse0
- Outcome
- total GHG emissionse0
- Direction
- highere0
- Comparator
- CKe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“broadcast CRUs exhibited significantly higher total GHG emissions than CK”
t0“rice”
Claim · model-written summary
Banded CRUs reduced total GHG emissions by 9.2% relative to broadcast CRUs.
- Taxon
- riceOryza sativat0
- Treatment
- banded CRUse0
- Outcome
- total GHG emissionse0
- Direction
- reducede0
- Value
- 9.2%e0
- Comparator
- broadcast CRUse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“banded CRUs significantly reduced the total GHG emissions in comparison with broadcast CRUs, by 9.2% averaged across the two years”
t0“rice”
Claim · model-written summary
Reduced CH4 emissions before middle drainage contributed substantially to the GHG difference.
- Taxon
- riceOryza sativat0
- Outcome
- GHG differencee0
- Qualifier
- Reduced CH4 emissions, particularly during the period prior to the middle drainagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced CH4 emissions, particularly during the period prior to the middle drainage, contributed largely to the GHG difference”
t0“rice”
Claim · model-written summary
Banded BBU had low yield-scaled GHG comparable to CK in both years.
- Taxon
- riceOryza sativat0
- Treatment
- banded BBUe0
- Outcome
- yield-scaled GHGe0
- Direction
- comparablee0
- Qualifier
- in both yearse0
- Comparator
- CKe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“banded BBU showed a low yield-scaled GHG (GHG emissions divided by grain yield) comparable to that under CK in both years”
t0“rice”
Claim · model-written summary
Broadcast CRU is unlikely to substitute for CK for grain yield or GHG emissions.
- Taxon
- riceOryza sativat0
- Outcome
- Broadcast CRU can hardly substitute for CK in terms of either grain yield or GHG emissionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Broadcast CRU can hardly substitute for CK in terms of either grain yield or GHG emissions”
t0“rice”
Claim · model-written summary
Banded BBU is recommended for sustaining rice production while minimizing environmental impacts.
- Taxon
- riceOryza sativae0
- Outcome
- banded BBU is a promising N management strategy for sustaining rice production while minimizing environmental impactse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“banded BBU is a promising N management strategy for sustaining rice production while minimizing environmental impacts”
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