Abstract
Low N fertilizer recovery efficiency (RE) remains a problem in rice ( Oryza sativa L.) production in Asia. The chlorophyll meter has been shown to identify when rice is in need of a N top‐dressing, that if applied would result in greater agronomic efficiency (AE) of N fertilizer than commonly practiced, pre‐set timing schemes. Critical chlorophyll meter readings have been used to match N top‐dressing with plant demand for the cultivar IR72, but fixed critical readings may not apply to multiple cultivars and locations. Our objective was to test the approach of using sufficiency indices, calculated from chlorophyll meter readings relative to well‐fertilized reference plots, with several rice cultivars in the Philippines and in India by comparing with local fixed N timing recommendations. Chlorophyll meter readings were significantly affected by N management practice, cultivar, and time of application at both locations. Similar rice yields were produced with chlorophyll meter sufficiency indices compared with the fixed N timing treatment with 30 kg less N ha −1 in the wet season in all cultivars at both locations. Compared with fixed‐timing, 45 kg less N ha −1 was used with the chlorophyll meter in the Philippines dry season without a yield reduction in three of four cultivars. In conclusion, chlorophyll meter sufficiency indices identified when several rice cultivars at two locations needed a N top‐dressing, which resulted in greater AE of N fertilizer than local, pre‐set splits.
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Claims 5
Claim · model-written summary
Chlorophyll meter readings differed significantly with nitrogen management practice, cultivar and application time at both locations.
- Taxon
- rice
Oryza sativat0 - Material
- cultivare0
- Treatment
- N management practicee0
- Outcome
- Chlorophyll meter readingse0
- Setting
- both locationse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorophyll meter readings were significantly affected by N management practice, cultivar, and time of application at both locations.”
t0“Rice”
Claim · model-written summary
In the wet season, sufficiency indices produced similar rice yields to fixed nitrogen timing while using 30 kg less nitrogen per hectare.
- Taxon
- riceOryza sativae0
- Treatment
- chlorophyll meter sufficiency indicese0
- Outcome
- rice yieldse0
- Direction
- Similare0
- Value
- 30 kg less N ha −1e0
- Qualifier
- wet season in all cultivars at both locationse0
- Comparator
- fixed N timing treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Similar rice yields were produced with chlorophyll meter sufficiency indices compared with the fixed N timing treatment with 30 kg less N ha −1 in the wet season in all cultivars at both locations.”
Claim · model-written summary
In the Philippines dry season, meter use saved 45 kg nitrogen per hectare without reducing yield in three of four cultivars.
- Taxon
- RiceOryza sativat0
- Treatment
- chlorophyll metere0
- Outcome
- N ha −1e0
- Direction
- lesse0
- Value
- 45 kg less N ha −1e0
- Qualifier
- dry season without a yield reduction in three of four cultivarse0
- Comparator
- fixed‐timinge0
- Setting
- Philippinese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with fixed‐timing, 45 kg less N ha −1 was used with the chlorophyll meter in the Philippines dry season without a yield reduction in three of four cultivars.”
t0“Rice”
Claim · model-written summary
Sufficiency indices identified nitrogen top-dressing needs across several cultivars and two locations.
- Taxon
- riceOryza sativae0
- Outcome
- needed a N top‐dressinge0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chlorophyll meter sufficiency indices identified when several rice cultivars at two locations needed a N top‐dressing”
Claim · model-written summary
The sufficiency-index approach gave greater agronomic nitrogen efficiency than local preset splits.
- Taxon
- RiceOryza sativat0
- Treatment
- chlorophyll meter sufficiency indicest0
- Outcome
- AE of N fertilizere0
- Direction
- greatere0
- Comparator
- local, pre‐set splitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which resulted in greater AE of N fertilizer than local, pre‐set splits.”
t0“chlorophyll meter sufficiency indices for Nitrogen Management of Irrigated Rice”
The same questions in other papers
chlorophyll · yield · Oryza sativa (rice)Positive and negative results
5 papers in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
- positive
3 papers more in this group
See all 7 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.