Fan et al. (2025) Grain yield and resource efficiency responses to water-nitrogen coupled input reduction: A global meta-analytical perspective

Identification

• Journal: Agricultural Water Management
• Year: 2025
• Date: 2025-12-07
• Authors: Qianwen Fan, Liangjun Fei, You‐Liang Peng, Yalin Gao, Fangyuan Shen
• DOI: 10.1016/j.agwat.2025.110059

Research Groups

State Key Laboratory of Water Engineering Ecology and Environment in Arid Area, Xi’an University of Technology, Xi’an, Shaanxi 710048, China

Short Summary

This meta-analysis systematically evaluated the impact of water-nitrogen coupling management under reduced water and fertilizer inputs on the yield, water use efficiency (WUE), and nitrogen partial factor productivity (NPFP) of maize, wheat, and potatoes. The study found that moderate reductions (approximately 10%) in water and nitrogen inputs significantly increased crop WUE and NPFP while maintaining high yields.

Objective

• To systematically evaluate the impact of water-nitrogen coupling management under water and nitrogen reduction conditions on the yield, water use efficiency (WUE), and nitrogen partial factor productivity (NPFP) of maize, wheat, and potatoes through a meta-analysis. The principal hypothesis is that moderate reductions in water and fertilizer inputs can synergistically optimize resource absorption and utilization, significantly improving WUE and NPFP while maintaining high crop yields, with essential differences in crop responses.

Study Configuration

• Spatial Scale: Data collected from 119 field studies across 8 countries, covering major global grain-producing areas.
• Temporal Scale: Literature published before January 2025.

Methodology and Data

• Models used: Meta-analysis (random effects model), Q-test, funnel plot, Egger test, Begg test for publication bias, quadratic regression for yield relationships, and path analysis. Data processing utilized SPSS 21.0, Stata 18, and Origin 2021.
• Data sources: Literature retrieved from Web of Science, Google Scholar, and China National Knowledge Infrastructure (CNKI). Data included field experiment results on irrigation levels, nitrogen application levels, crop yield, water use efficiency (WUE), and nitrogen partial factor productivity (NPFP) for maize, wheat, and potato.

Main Results

• Moderate water and nitrogen reductions (e.g., 80–99% of full irrigation/maximum nitrogen) substantially increased crop water use efficiency (WUE) and nitrogen partial factor productivity (NPFP) while maintaining high yields.
• Extreme reductions in water and nitrogen led to significant yield declines, with potatoes experiencing the largest loss (up to -96.06%).
• Optimal water-nitrogen coupling levels for maximum yields were:
  • Maize: 0.87I (full irrigation volume) and 0.81 N (maximum nitrogen application), yielding 1.33 × 10^4 kg⋅ha−1.
  • Wheat: 0.87I and 0.84 N, yielding 8.93 × 10^3 kg⋅ha−1.
  • Potato: 0.90I and 0.81 N, yielding 9.25 × 10^4 kg⋅ha−1.
• Integrated water-nitrogen management resulted in significantly higher yields with lower overall water and fertilizer inputs compared to single-factor management.
• The effects of water-nitrogen coupling were strongly influenced by soil types, climate (rainfall and temperature), and soil organic matter content.
• Crops in arid and semi-arid environments were more sensitive to water and fertilizer reductions than those in semi-humid environments.
• Both low (≤8 °C) and high (>12 °C) temperatures inhibited crop yield, while moderate temperatures (8–12 °C) improved WUE and NPFP.
• Clay soil demonstrated better adaptability to water-nitrogen coupling, maintaining higher NPFP, whereas sandy loam and silty loam experienced greater yield declines due to water loss.
• Path analysis identified irrigation level and annual average temperature as the main factors affecting maize yield, irrigation and fertilization levels for wheat, and rainfall, irrigation level, and organic matter for potato.

Contributions

• This study provides the first systematic quantification and comparison of optimal water and nitrogen reduction thresholds for maize, wheat, and potato under water-nitrogen coupling using a meta-analytical approach.
• It reveals fundamental differences in crop-specific responses to water and nitrogen reduction, categorizing them as 'water retention and nitrogen reduction' for potato, 'simultaneous water and nitrogen reduction with higher nitrogen reduction tolerance' for maize, and 'water and nitrogen fine-tuning' for wheat.
• The research offers a unified threshold comparison framework, providing a scientific benchmark for formulating differentiated national or regional agricultural policies.
• It comprehensively considers the interactive effects of climate and soil conditions on crop yield, WUE, and NPFP, addressing limitations of previous single-factor studies.
• The findings provide robust scientific evidence to support the optimization of water-nitrogen coupling strategies for sustainable agricultural development, particularly in the context of increasing water scarcity and environmental concerns.

Funding

• National Natural Science Foundation of China (52079105)
• Shaanxi Provincial Water Conservancy Science and Technology Project (2024slkj-4)

Citation

@article{Fan2025Grain,
  author = {Fan, Qianwen and Fei, Liangjun and Peng, You‐Liang and Gao, Yalin and Shen, Fangyuan},
  title = {Grain yield and resource efficiency responses to water-nitrogen coupled input reduction: A global meta-analytical perspective},
  journal = {Agricultural Water Management},
  year = {2025},
  doi = {10.1016/j.agwat.2025.110059},
  url = {https://doi.org/10.1016/j.agwat.2025.110059}
}