Abstract
Mitigating environmental impacts while enhancing grain yield is essential for sustainable rice production. One-time urea deep placement (UDP) has been recognized for its potential to reduce nitrogen (N) loss and improve rice yield. However, this method applies an excessive amount of nitrogen as a basal fertilizer, which increases N₂O emissions during the mid-season aeration (MSA) phase and promotes straw biomass over grain yield, consequently reducing the harvest index (HI). The split injection of water-soluble fertilizers (IF) could present a viable alternative solution. Nevertheless, no studies have yet investigated the environmental and agronomic effects of IF in rice production fields. Therefore, a three-year field experiment was conducted with six treatments: three-split urea broadcasting (BU), one-time UDP (UDP(10:0)), one-time IF (IF(10:0)), two-split IF with a 6:4 ratio (IF(6:4)), two-split IF with a 5:5 ratio (IF(5:5)), and a control without N (CK) in an intensive rice cropping system in China. Results showed that one-time UDP produced the lowest HI and increased N 2 O emissions by 146 % compared to BU, due to surplus N provision until the MSA stage. In contrast, two-split IF treatments increased straw biomass by 7 %-9 % while improving rice yield by 13 %-14 % compared to BU and resulting in the highest HI, due to the reduced injection dosage of basal fertilizer and sufficient spike fertilizer injection, which in turn avoided surplus N at the MSA stage, thus decreasing total N 2 O emissions by 15 %-28 % compared to BU. All deep fertilization treatments reduced CH 4 emissions by 43 %-67 % compared to BU. All IF treatments produced the parallel highest net economic benefit (NEB) of all treatments. Moreover, IF(6:4) reduced greenhouse gas intensity (GHGI) by 56 % compared to BU, and completely eliminated NH 3 volatilization. In conclusion, a two-split IF with a basal and spike fertilizer ratio of 6:4 is a promising strategy for reducing GHGI and NH 3 emissions while simultaneously improving rice yield, HI and NEB in paddy rice fields. Expanding split IF technology will greatly contribute to the green development of rice production. • Two-split injection of water-soluble fertilizers (IF) eliminated N surplus at the mid-season aeration stage. • Two-split IF significantly reduced N 2 O, CH 4 and NH 3 emissions simultaneously. • Two-split IF offered higher rice yield, harvest index and net economic benefit.
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Claims 11
Claim · model-written summary
One-time UDP produced the lowest harvest index.
- Taxon
- rice
Oryza sativat0 - Treatment
- one-time UDPe0
- Outcome
- HIe0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“one-time UDP produced the lowest HI”
t0“rice”
Claim · model-written summary
One-time UDP increased N 2 O emissions 146 % versus BU.
- Taxon
- riceOryza sativat0
- Treatment
- one-time UDPe0
- Outcome
- N 2 O emissionse0
- Direction
- increasede0
- Value
- 146 %e0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“one-time UDP produced the lowest HI and increased N 2 O emissions by 146 % compared to BU”
t0“rice”
Claim · model-written summary
Two-split IF increased straw biomass 7 %-9 % versus BU.
- Taxon
- riceOryza sativat0
- Treatment
- two-split IF treatmentse0
- Outcome
- straw biomasse0
- Direction
- increasede0
- Value
- 7 %-9 %e0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two-split IF treatments increased straw biomass by 7 %-9 % while improving rice yield by 13 %-14 % compared to BU”
t0“rice”
Claim · model-written summary
Two-split IF improved rice yield 13 %-14 % versus BU.
- Taxon
- riceOryza sativae0
- Treatment
- two-split IF treatmentse0
- Outcome
- rice yielde0
- Direction
- improvinge0
- Value
- 13 %-14 %e0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two-split IF treatments increased straw biomass by 7 %-9 % while improving rice yield by 13 %-14 % compared to BU”
Claim · model-written summary
Two-split IF yielded the highest harvest index.
- Taxon
- riceOryza sativat0
- Treatment
- two-split IF treatmentse0
- Outcome
- HIe0
- Direction
- higheste0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two-split IF treatments increased straw biomass by 7 %-9 % while improving rice yield by 13 %-14 % compared to BU and resulting in the highest HI”
t0“rice”
Claim · model-written summary
Two-split IF decreased total N 2 O emissions 15 %-28 % versus BU.
- Taxon
- riceOryza sativat0
- Treatment
- two-split IF treatmentse1
- Outcome
- total N 2 O emissionse0
- Direction
- decreasinge0
- Value
- 15 %-28 %e0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreasing total N 2 O emissions by 15 %-28 % compared to BU”
e1“two-split IF treatments increased straw biomass”
t0“rice”
Claim · model-written summary
All deep fertilization treatments reduced CH 4 emissions 43 %-67 % versus BU.
- Taxon
- riceOryza sativat0
- Treatment
- deep fertilization treatmentse0
- Outcome
- CH 4 emissionse0
- Direction
- reducede0
- Value
- 43 %-67 %e0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All deep fertilization treatments reduced CH 4 emissions by 43 %-67 % compared to BU”
t0“rice”
Claim · model-written summary
All IF treatments produced the joint highest net economic benefit.
- Taxon
- riceOryza sativat0
- Treatment
- IF treatmentse0
- Outcome
- net economic benefit (NEB)e0
- Direction
- higheste0
- Comparator
- all treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All IF treatments produced the parallel highest net economic benefit (NEB) of all treatments”
t0“rice”
Claim · model-written summary
IF(6:4) reduced GHGI 56 % versus BU.
- Taxon
- riceOryza sativat0
- Treatment
- IF(6:4)e0
- Outcome
- greenhouse gas intensity (GHGI)e0
- Direction
- reducede0
- Value
- 56 %e0
- Comparator
- BUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IF(6:4) reduced greenhouse gas intensity (GHGI) by 56 % compared to BU”
t0“rice”
Claim · model-written summary
IF(6:4) eliminated NH 3 volatilization.
- Taxon
- riceOryza sativat0
- Treatment
- IF(6:4)e0
- Outcome
- NH 3 volatilizatione0
- Direction
- eliminatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IF(6:4) reduced greenhouse gas intensity (GHGI) by 56 % compared to BU, and completely eliminated NH 3 volatilization”
t0“rice”
Claim · model-written summary
The authors recommend two-split IF at a 6:4 basal to spike ratio.
- Taxon
- riceOryza sativat0
- Outcome
- two-split IF with a basal and spike fertilizer ratio of 6:4e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a two-split IF with a basal and spike fertilizer ratio of 6:4 is a promising strategy for reducing GHGI and NH 3 emissions while simultaneously improving rice yield, HI and NEB”
t0“rice”
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