Wang et al. (2026) Green Manure Enables Reduced Water and Nitrogen Inputs with Sustained Yield in Maize

Identification

• Journal: Agronomy
• Year: 2026
• Date: 2026-01-02
• Authors: Feng Wang, Yanzi Yu, Xiao Pang, Yali Sun, Zhilong Fan, Wen Yin, Falong Hu, Wei He, Yunyou Nan, Aizhong Yu
• DOI: 10.3390/agronomy16010120

Research Groups

• State Key Laboratory of Aridland Crop Science, Seed Industry Research Institute, College of Agronomy, Gansu Agricultural University, Lanzhou, China

Short Summary

This study investigated whether legume green manure incorporation could enable reduced water and nitrogen inputs while sustaining maize yield in arid irrigated areas. A two-year field experiment demonstrated that a 20% co-reduction in irrigation and nitrogen maintained stable maize yield and significantly improved water and nitrogen use efficiencies.

Objective

• To determine if water and nitrogen inputs could be concurrently reduced without compromising maize productivity under legume green manure incorporation in arid irrigated areas.
• To test the hypothesis that a moderate, synchronized reduction in irrigation and nitrogen fertilizer under green manure incorporation can improve the soil water-nitrogen environment, sustain physiological function in maize, and enhance water and nitrogen use efficiencies without compromising yield over the short experimental period.

Study Configuration

• Spatial Scale: Wuwei Oasis Agricultural Comprehensive Experiment Station of Gansu Agricultural University (103°5′ E, 37°31′ N), located at an altitude of 1770 m in the eastern end of the Hexi Corridor, Northwest China, characterized by a cold-temperate arid climate zone.
• Temporal Scale: Two-year field experiment (2024–2025) covering the maize growing season.

Methodology and Data

• Models used:
  • Logistic equation for modeling dry matter accumulation dynamics.
  • Water balance equation for calculating actual crop evapotranspiration (ETc).
  • Structural Equation Modeling (SEM) using AMOS 22.0 to quantify direct and indirect influences of soil properties on yield.
• Data sources:
  • Field experiment data from a split-plot design with three irrigation levels (405 mm, 324 mm, 243 mm) and three nitrogen rates (360 kg·ha⁻¹, 288 kg·ha⁻¹, 216 kg·ha⁻¹).
  • Gravimetric method for soil water content (SWC) in 0–110 cm profile.
  • Smartchem 450 automated chemical analyzer for soil total nitrogen (STN).
  • Length–width coefficient method for leaf area index (LAI).
  • LI-6800XT portable photosynthesis system for net photosynthetic rate (Pₙ) and transpiration rate (Tᵣ).
  • SPAD-502 Plus chlorophyll meter for relative chlorophyll content (SPAD).
  • Oven-drying method for plant dry matter (DM) accumulation.
  • Grain yield (GY) and yield components (ear number, kernel number per ear, 1000-kernel weight) measured at maturity.
  • Meteorological data (temperature, precipitation) from the experimental area.

Main Results

• A combined 20% reduction in water and nitrogen inputs (I2N2 treatment) maintained maize grain yield (GY) and its components (ear number, kernel number per ear, 1000-kernel weight) at levels comparable to conventional management (I1N1).
• The I2N2 treatment significantly increased water use efficiency (WUE) by 7.6% and nitrogen use efficiency for grain yield (NUtEg) by 11.7% compared to conventional management.
• Excessive water reduction (40%, I3) or nitrogen reduction (40%, N3) significantly inhibited maize growth, reduced dry matter accumulation, and decreased yield (p < 0.05).
• The I2N2 treatment maintained stable leaf area index (LAI), net photosynthetic rate (Pₙ), transpiration rate (Tᵣ), and SPAD values throughout the growth period, similar to conventional management.
• Soil water content (0–110 cm profile) and soil total nitrogen at the silking stage under I2N2 did not differ significantly from I1N1, indicating a favorable soil water and nitrogen environment.
• Structural Equation Modeling (SEM) revealed that soil water content (SWC) and soil total nitrogen (STN) indirectly affected Pₙ and Tᵣ by regulating LAI and SPAD (path coefficients: 0.48–0.62), which in turn drove dry matter accumulation and determined grain yield (R² = 0.81).

Contributions

• This study provides preliminary, short-term evidence for the feasibility of an integrated management strategy combining legume green manure incorporation with a moderate (20%) co-reduction in water and nitrogen inputs in arid irrigated maize systems.
• It demonstrates that this approach can sustain maize yield while simultaneously enhancing water and nitrogen use efficiencies, offering a promising pathway for sustainable agriculture in water-limited regions.
• The research elucidates the physiological and soil-level mechanisms (e.g., maintained photosynthetic capacity, improved soil water-nitrogen environment) through which green manure compensates for reduced inputs, contributing to a systematic understanding of the soil-plant-yield continuum.

Funding

• Research Program of the State Key Laboratory of Aridland Crop Science of China (GSCS-2023-16)
• National Natural Science Foundation of China (32460549)
• National Key Research and Development Program of China (2022YFD1900200, 2022YFD1900300)
• Gansu Province Research and Production Integration Technology Empowerment Program Project (25FNNA003-2-2)
• Corn Industry Technology System for Modern Cold and Arid Agriculture in Gansu Province (GSARS08-05)
• Innovation Fund for Higher Education Institutions Teacher in Gansu Province (2025A-081)
• Gansu Province Joint Research Foundation of China (24JRRA844)
• Gansu Agricultural University Public Recruitment Doctoral Scientific Research Startup Project (GAU-KYQD-2021-16)

Citation

@article{Wang2026Green,
  author = {Wang, Feng and Yu, Yanzi and Pang, Xiao and Sun, Yali and Fan, Zhilong and Yin, Wen and Hu, Falong and He, Wei and Nan, Yunyou and Yu, Aizhong},
  title = {Green Manure Enables Reduced Water and Nitrogen Inputs with Sustained Yield in Maize},
  journal = {Agronomy},
  year = {2026},
  doi = {10.3390/agronomy16010120},
  url = {https://doi.org/10.3390/agronomy16010120}
}