Abstract
This study aimed to systematically evaluate the effects of different nitrogen application rates and irrigation practices on water-saving and yield enhancement in winter wheat production in the North China Plain (NCP) using a meta-analysis. By quantifying the impacts on crop yield, nitrogen use efficiency (NUE), and water use efficiency (WUE), the research provides a scientific basis for optimizing management practices in winter wheat production in this region. A comprehensive literature search was conducted across multiple databases, resulting in the inclusion of 94 eligible studies from 2018 to 2023. A random-effects model was employed to calculate the combined effect sizes, followed by subgroup and sensitivity analyses to further investigate the influence of nitrogen application rates, irrigation methods, and study regions on winter wheat production efficiency. The findings reveal that increasing nitrogen application rates and adopting deficit irrigation practices significantly improved winter wheat yield (combined effect size: 4.53 t·ha−1), NUE (43.29%), and WUE (0.013 t·ha−1·mm−1). The subgroup analysis further elucidated the critical roles of nitrogen application ratios, irrigation methods, and study regions in determining winter wheat production efficiency, while the sensitivity analysis confirmed the robustness of these findings, as the pooled effect sizes decreased by merely 0.69% and increased by 0.61% after excluding small-sample or highly biased studies, respectively. The above meta-analysis did not incorporate long-term field trials; hence, two-year field experiments with designed irrigation and organic–inorganic fertilizer treatments were conducted, which provided further validation for the meta-analysis. Under short-term conditions (excluding CO2 effects), we observed that chemical fertilizer exhibited a measurable inhibitory effect on crop water uptake and optimal water–fertilizer management was achieved with a 7:3 inorganic–organic fertilizer ratio combined with 450 m3·ha−1 irrigation. This study demonstrates the effectiveness of optimizing nitrogen fertilization and irrigation management in enhancing winter wheat yield and resource utilization efficiency. The findings offer actionable insights for sustainable agricultural practices in the NCP and similar regions, contributing to improved crop productivity and resource conservation.
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Claims 8
Claim · model-written summary
Increasing nitrogen rates and deficit irrigation significantly improved winter wheat yield, with a combined effect size of 4.53 t·ha−1.
- Taxon
- winter wheat
Triticum aestivume0 - Treatment
- increasing nitrogen application rates and adopting deficit irrigation practicese1
- Outcome
- yielde1
- Direction
- improvede1
- Value
- 4.53 t·ha−1e1
- Setting
- North China Plaine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e1“increasing nitrogen application rates and adopting deficit irrigation practices significantly improved winter wheat yield (combined effect size: 4.53 t·ha−1), NUE (43.29%), and WUE (0.013 t·ha−1·mm−1)”
Claim · model-written summary
Increasing nitrogen rates and deficit irrigation significantly improved winter wheat nitrogen use efficiency, with an effect of 43.29%.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- increasing nitrogen application rates and adopting deficit irrigation practicese1
- Outcome
- NUEe1
- Direction
- improvede1
- Value
- 43.29%e1
- Setting
- North China Plaine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e1“increasing nitrogen application rates and adopting deficit irrigation practices significantly improved winter wheat yield (combined effect size: 4.53 t·ha−1), NUE (43.29%), and WUE (0.013 t·ha−1·mm−1)”
Claim · model-written summary
Increasing nitrogen rates and deficit irrigation significantly improved winter wheat water use efficiency, with an effect of 0.013 t·ha−1·mm−1.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- increasing nitrogen application rates and adopting deficit irrigation practicese1
- Outcome
- WUEe1
- Direction
- improvede1
- Value
- 0.013 t·ha−1·mm−1e1
- Setting
- North China Plaine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e1“increasing nitrogen application rates and adopting deficit irrigation practices significantly improved winter wheat yield (combined effect size: 4.53 t·ha−1), NUE (43.29%), and WUE (0.013 t·ha−1·mm−1)”
Claim · model-written summary
Nitrogen application ratios, irrigation methods and study regions were critical in determining winter wheat production efficiency.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- nitrogen application ratios, irrigation methods, and study regionse2
- Outcome
- winter wheat production efficiencye2
- Setting
- North China Plaine0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e2“The subgroup analysis further elucidated the critical roles of nitrogen application ratios, irrigation methods, and study regions in determining winter wheat production efficiency”
Claim · model-written summary
Excluding small-sample studies decreased the pooled effect sizes of winter wheat by 0.69%.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- excluding small-samplee3
- Outcome
- pooled effect sizese3
- Direction
- decreasede3
- Value
- 0.69%e3
- Setting
- North China Plaine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e3“the pooled effect sizes decreased by merely 0.69% and increased by 0.61% after excluding small-sample or highly biased studies, respectively”
Claim · model-written summary
Excluding highly biased studies increased the pooled effect sizes of winter wheat by 0.61%.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- highly biased studiese3
- Outcome
- pooled effect sizese3
- Direction
- increasede3
- Value
- 0.61%e3
- Setting
- North China Plaine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e3“the pooled effect sizes decreased by merely 0.69% and increased by 0.61% after excluding small-sample or highly biased studies, respectively”
Claim · model-written summary
Chemical fertilizer had a measurable inhibitory effect on crop water uptake of winter wheat under short-term conditions.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- chemical fertilizere4
- Outcome
- crop water uptakee4
- Direction
- inhibitorye4
- Qualifier
- Under short-term conditions (excluding CO2 effects)e4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e4“Under short-term conditions (excluding CO2 effects), we observed that chemical fertilizer exhibited a measurable inhibitory effect on crop water uptake”
Claim · model-written summary
Optimal water–fertilizer management for winter wheat was achieved with a 7:3 inorganic–organic fertilizer ratio and 450 m3·ha−1 irrigation.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- 7:3 inorganic–organic fertilizer ratio combined with 450 m3·ha−1 irrigatione5
- Outcome
- optimal water–fertilizer managemente5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“winter wheat production in the North China Plain (NCP)”
e5“optimal water–fertilizer management was achieved with a 7:3 inorganic–organic fertilizer ratio combined with 450 m3·ha−1 irrigation”
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