Abstract
Abstract The 15 N balance at harvest, the residual effects of applied N fertilizer, and the distribution of N by depth in a wetland rice ( Oryza sativa L.) soil (Alfisol) were determined in field experiments using 15 N‐labeled urea. Nitrogen‐15 balance data show that with point, deep placement of urea supergranules (USG), only 4 to 5% of the applied N was unaccounted for after harvest of both the dry‐season and wet‐season crops. In contrast, when prilled urea was basally broadcast and incorporated and topdressed at panicle initiation (PI), 11 to 35% of the applied N was not recovered at harvest, indicating substantial loss of fertilizer N, especially when poor incorporation resulted in high floodwater mineral‐N levels. Uniform deep placement also resulted in high recovery of 15 N (92–107%), confirming that the high total 15 N recovery obtained with point deep‐placement of USG was largely a function of depth of placement. Band application of urea gave complete 15 N recovery (102%) in the dry season and low recovery (61%) in the wet. Nitrogen‐15 balance data showed that 22 to 56% of the applied urea‐N still remained in the soil after the final harvest. The uptake by the wet season crop of the residual labeled soil N from the dry season experiment was about 5% of the initial applied N (87 kg N/ha) for all treatments. Placement method appeared to influence the actual recovery of residual soil 15 N; the percentage recovery from the USG treatment was highest and that from the split urea treatment lowest. In neither the dry season nor the wet season was 15 N enrichment significant in soil below 30 cm. Generally, the distribution of the residual 15 N in soil reflected the placement pattern of urea.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 10
Claim · model-written summary
Point deep placement of urea supergranules left 4 to 5% of applied nitrogen unaccounted for after both crops.
- Taxon
- rice
Oryza sativat0 - Treatment
- point, deep placement of urea supergranules (USG)e0
- Outcome
- applied N was unaccounted fore0
- Direction
- onlye0
- Value
- 4 to 5%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with point, deep placement of urea supergranules (USG), only 4 to 5% of the applied N was unaccounted for after harvest of both the dry‐season and wet‐season crops”
t0“Wetland Rice Fields”
Claim · model-written summary
Broadcast and split prilled urea left 11 to 35% of applied nitrogen unrecovered at harvest.
- Taxon
- riceOryza sativat0
- Treatment
- prilled urea was basally broadcast and incorporated and topdressed at panicle initiation (PI)e0
- Outcome
- applied N was not recovered at harveste0
- Direction
- not recoverede0
- Value
- 11 to 35%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when prilled urea was basally broadcast and incorporated and topdressed at panicle initiation (PI), 11 to 35% of the applied N was not recovered at harvest”
t0“Wetland Rice Fields”
Claim · model-written summary
Uniform deep placement recovered 92–107% of labeled nitrogen.
- Taxon
- riceOryza sativat0
- Treatment
- Uniform deep placemente0
- Outcome
- recovery of 15 Ne0
- Direction
- highe0
- Value
- 92–107%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Uniform deep placement also resulted in high recovery of 15 N (92–107%)”
t0“Wetland Rice Fields”
Claim · model-written summary
Band application produced 102% recovery in the dry season.
- Taxon
- riceOryza sativat0
- Treatment
- Band application of ureae0
- Outcome
- 15 N recoverye0
- Direction
- completee0
- Value
- 102%e0
- Qualifier
- dry seasone0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Band application of urea gave complete 15 N recovery (102%) in the dry season”
t0“Wetland Rice Fields”
Claim · model-written summary
Band application produced 61% recovery in the wet season.
- Taxon
- riceOryza sativat0
- Treatment
- Band application of ureae0
- Outcome
- recoverye0
- Direction
- lowe0
- Value
- 61%e0
- Qualifier
- wete0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Band application of urea gave complete 15 N recovery (102%) in the dry season and low recovery (61%) in the wet”
t0“Wetland Rice Fields”
Claim · model-written summary
After final harvest, 22 to 56% of applied urea nitrogen remained in soil.
- Taxon
- riceOryza sativat0
- Outcome
- applied urea‐N still remained in the soile0
- Value
- 22 to 56%e0
- Qualifier
- after the final harveste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“22 to 56% of the applied urea‐N still remained in the soil after the final harvest”
t0“Wetland Rice Fields”
Claim · model-written summary
The wet season crop took up about 5% of initial applied nitrogen from residual labeled soil nitrogen across treatments.
- Taxon
- riceOryza sativat0
- Outcome
- uptake by the wet season crop of the residual labeled soil Ne0
- Value
- about 5%e0
- Qualifier
- for all treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The uptake by the wet season crop of the residual labeled soil N from the dry season experiment was about 5% of the initial applied N (87 kg N/ha) for all treatments”
t0“Wetland Rice Fields”
Claim · model-written summary
Recovery of residual soil nitrogen was highest with supergranules and lowest with split urea.
- Taxon
- riceOryza sativat0
- Treatment
- USG treatmente0
- Outcome
- percentage recoverye0
- Direction
- higheste0
- Comparator
- split urea treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the percentage recovery from the USG treatment was highest and that from the split urea treatment lowest”
t0“Wetland Rice Fields”
Claim · model-written summary
Soil below 30 cm had no significant nitrogen enrichment in either season.
- Taxon
- riceOryza sativat0
- Outcome
- 15 N enrichmente0
- Qualifier
- soil below 30 cme0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In neither the dry season nor the wet season was 15 N enrichment significant in soil below 30 cm”
t0“Wetland Rice Fields”
Claim · model-written summary
Residual soil nitrogen distribution reflected the urea placement pattern.
- Taxon
- riceOryza sativat0
- Treatment
- placement pattern of ureae0
- Outcome
- distribution of the residual 15 N in soile0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the distribution of the residual 15 N in soil reflected the placement pattern of urea”
t0“Wetland Rice Fields”
The same questions in other papers
transplanting · yield · Oryza sativa (rice)Positive and negative results
155 papers in the same direction as this paper · 922 in the opposite direction
- positive
- positive
- positive
1,074 papers more in this group
See all 1,078 papers →nitrogen · yield · Oryza sativa (rice)Positive and negative results
241 papers in the same direction as this paper · 1,803 in the opposite direction
- positive
- positive
- positive
2,041 papers more in this group
See all 2,045 papers →fertilization · yield · Oryza sativa (rice)Positive and negative results
271 papers in the same direction as this paper · 3,183 in the opposite direction
- positive
- positive
- positive
3,451 papers more in this group
See all 3,455 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.