Abstract
Abstract Nitrogen fertilizer optimization algorithm (NFOA) and nitrogen nutrition index (NNI) have been developed to achieve higher yield and N use efficiency. This study was to improve NFOA and NNI strategies for managing rice N nutrition based on portable Soil and Plant Analyzer Development (SPAD) meter. Four field experiments were conducted in 2013–2014 to generate diverse N fertilizer rates in rice cultivars at three eco‐sites. Nitrogen indicators SPAD readings were measured to establish SPAD‐based management strategies. Two experiments were conducted to assess the effectiveness of developed NFOA and NNI algorithm for upward and downward adjustment of N‐fertilizer doses twice within the growing season in 2015. New N‐adjustment strategies optimized N topdressing by upward‐, fine‐, and downward‐ adjustment with an average N‐application rate of 264–272 kg N ha −1 in eastern China. Maximum grain yield (10.5 t ha −1 ) was obtained when 264 kg N ha −1 was applied. The recovery efficiency of N fertilizer was higher for NFOA and NNI (51–57%) than fixed‐time application of 270 kg N ha −1 (48%). The comparable high net profit (>$1080 ha −1 ) was achieved with lower N‐adjustment fertilizer input in 270 and 360 kg N ha −1 treatments. SPAD‐based NFOA and NNI methods are practical approaches for reducing excessive use of N fertilizer, achieving slight increase in yield, and net profit was decreased (360 kg N ha −1 ). More refinements are necessary to ensure that these strategies can be used for yield‐ and income‐enhancing production for farmers.
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Claims 9
Claim · model-written summary
The strategies adjusted nitrogen topdressing at 264–272 kg N ha −1 on average.
- Taxon
- rice
Oryza sativat0 - Outcome
- N topdressinge0
- Value
- 264–272 kg N ha −1e0
- Setting
- eastern Chinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“New N‐adjustment strategies optimized N topdressing by upward‐, fine‐, and downward‐ adjustment with an average N‐application rate of 264–272 kg N ha −1 in eastern China.”
t0“rice”
Claim · model-written summary
Maximum grain yield was 10.5 t ha −1 at 264 kg N ha −1.
- Taxon
- riceOryza sativat0
- Treatment
- 264 kg N ha −1e0
- Outcome
- grain yielde0
- Direction
- Maximume0
- Value
- 10.5 t ha −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maximum grain yield (10.5 t ha −1 ) was obtained when 264 kg N ha −1 was applied.”
t0“rice”
Claim · model-written summary
NFOA nitrogen recovery efficiency was higher than fixed time application.
- Taxon
- riceOryza sativat0
- Outcome
- recovery efficiency of N fertilizere0
- Direction
- highere0
- Value
- 51–57%e0
- Comparator
- fixed‐time application of 270 kg N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The recovery efficiency of N fertilizer was higher for NFOA and NNI (51–57%) than fixed‐time application of 270 kg N ha −1 (48%).”
t0“rice”
Claim · model-written summary
NNI nitrogen recovery efficiency was higher than fixed time application.
- Taxon
- riceOryza sativat0
- Outcome
- recovery efficiency of N fertilizere0
- Direction
- highere0
- Value
- 51–57%e0
- Comparator
- fixed‐time application of 270 kg N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The recovery efficiency of N fertilizer was higher for NFOA and NNI (51–57%) than fixed‐time application of 270 kg N ha −1 (48%).”
t0“rice”
Claim · model-written summary
Lower nitrogen adjustment input achieved comparable high net profit above $1080 per hectare.
- Taxon
- riceOryza sativat0
- Treatment
- lower N‐adjustment fertilizer inpute0
- Outcome
- net profite0
- Value
- >$1080 ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The comparable high net profit (>$1080 ha −1 ) was achieved with lower N‐adjustment fertilizer input in 270 and 360 kg N ha −1 treatments.”
t0“rice”
Claim · model-written summary
SPAD NFOA and NNI methods reduced excessive nitrogen use.
- Taxon
- riceOryza sativat0
- Outcome
- excessive use of N fertilizere0
- Direction
- reducinge0
Not reportedValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SPAD‐based NFOA and NNI methods are practical approaches for reducing excessive use of N fertilizer”
t0“rice”
Claim · model-written summary
SPAD methods slightly increased yield.
- Taxon
- riceOryza sativat0
- Outcome
- yielde0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“achieving slight increase in yield”
t0“rice”
Claim · model-written summary
Net profit decreased in the 360 kg N ha −1 treatment.
- Taxon
- riceOryza sativat0
- Treatment
- 360 kg N ha −1e0
- Outcome
- net profite0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“net profit was decreased (360 kg N ha −1 ).”
t0“rice”
Claim · model-written summary
Authors called for refinements to enhance farmer yield and income.
- Taxon
- riceOryza sativat0
- Outcome
- More refinements are necessarye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“More refinements are necessary to ensure that these strategies can be used for yield‐ and income‐enhancing production for farmers.”
t0“rice”
The same questions in other papers
nitrogen · yield · Oryza sativa (rice)Positive and negative results
1,802 papers in the same direction as this paper · 193 in the opposite direction · 49 reporting no difference from an alternative
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