Abstract
Nitrogen use efficiency (NUE) serves as a useful performance indicator to benchmark agricultural nitrogen management. It is determined by genotype-environment-management interaction, making the quantification of the key drivers and the mechanism behind spatiotemporal trends of NUE challenging. In this study, the soil Water Heat Carbon Nitrogen Simulator (WHCNS) model, integrated with multi-scale datasets, was applied to clarify the key drivers of the NUE trends for single rice in China from 1978 to 2019. The national NUE for single rice was 0.31 over the study period and showed a slight increase before 2005 and afterwards a rapid increase of 0.048/10 years, primarily controlled by fertilization management and cultivar shifts. The N application rate determined the total N input, influenced the N uptake and utilization efficiency, and therefore the NUE, while the effect of cultivar shifts on NUE is mainly determined by the increase in the proportion of photosynthetic products in the rice grain and thus the harvest index. The benefits of cultivar improvement (0.034/10 years) which were almost entirely offset by the excessive use of N fertilizers (-0.029/10 years) before 2005, became lower (0.021/10 years) and unstable thereafter in many subregions, indicating the challenge of cultivar selection under low N inputs. To reach the ambitious NUE target of 0.6 by 2050 for rice, improving NUE through better management alone will not be enough. Improvements in rice breeding are therefore urgently needed to meet future NUE challenges in rice production under climate change and population growth.
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Claims 10
Claim · model-written summary
National single rice NUE was 0.31 over 1978–2019.
Verbatim
e0“The national NUE for single rice was 0.31 over the study period”
t0“China”
Claim · model-written summary
Single rice NUE rose slightly before 2005.
Verbatim
e0“showed a slight increase before 2005”
t0“single rice”
Claim · model-written summary
Single rice NUE rose by 0.048 per decade after 2005.
Verbatim
e0“afterwards a rapid increase of 0.048/10 years”
t0“single rice”
Claim · model-written summary
Fertilization management and cultivar shifts primarily controlled NUE trends.
Verbatim
e0“The national NUE for single rice was 0.31 over the study period and showed a slight increase before 2005 and afterwards a rapid increase of 0.048/10 years, primarily controlled by fertilization management and cultivar shifts”
t0“single rice”
Claim · model-written summary
N application rate determined total N input and affected N uptake and utilization efficiency and NUE.
- Taxon
- rice
Oryza sativat0 - Treatment
- N application ratee0
- Outcome
- NUEe0
- Qualifier
- influenced the N uptake and utilization efficiencye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N application rate determined the total N input, influenced the N uptake and utilization efficiency, and therefore the NUE”
t0“rice”
Claim · model-written summary
Cultivar shifts influenced NUE through a higher grain share of photosynthetic products and harvest index.
- Taxon
- riceOryza sativae0
- Material
- cultivar shiftse0
- Organ / stage
- rice graine0
- Outcome
- NUEe0
- Direction
- increasee0
- Qualifier
- harvest indexe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effect of cultivar shifts on NUE is mainly determined by the increase in the proportion of photosynthetic products in the rice grain and thus the harvest index”
Claim · model-written summary
Cultivar improvement contributed 0.034 per decade to NUE before 2005.
- Taxon
- riceOryza sativat0
- Outcome
- benefits of cultivar improvemente0
- Value
- 0.034/10 yearse0
- Qualifier
- before 2005e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The benefits of cultivar improvement (0.034/10 years) which were almost entirely offset by the excessive use of N fertilizers (-0.029/10 years) before 2005”
t0“rice”
Claim · model-written summary
Excess N fertilizer use offset NUE gains by -0.029 per decade before 2005.
- Taxon
- riceOryza sativat0
- Treatment
- excessive use of N fertilizerse0
- Outcome
- benefitse0
- Direction
- offsete0
- Value
- -0.029/10 yearse0
- Qualifier
- before 2005e0
- Comparator
- cultivar improvemente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The benefits of cultivar improvement (0.034/10 years) which were almost entirely offset by the excessive use of N fertilizers (-0.029/10 years) before 2005”
t0“rice”
Claim · model-written summary
Cultivar improvement benefits fell to 0.021 per decade after 2005 and were unstable in many subregions.
- Taxon
- riceOryza sativat0
- Outcome
- benefits of cultivar improvemente0
- Direction
- lowere0
- Value
- 0.021/10 yearse0
- Qualifier
- unstable thereafter in many subregionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The benefits of cultivar improvement (0.034/10 years) which were almost entirely offset by the excessive use of N fertilizers (-0.029/10 years) before 2005, became lower (0.021/10 years) and unstable thereafter in many subregions”
t0“rice”
Claim · model-written summary
The authors recommend rice breeding improvements to meet future NUE challenges.
- Taxon
- riceOryza sativae0
- Outcome
- Improvements in rice breedinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Improvements in rice breeding are therefore urgently needed to meet future NUE challenges in rice production”