Zhang et al. (2026) Potential effect of irrigation conversion on rice yields and self-sufficiency in the Philippines under future climate

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-11-04
• Authors: Tianyi Zhang, Rubenito M. Lampayan, Roger Luyun, Leunell C.M. Buela, Nanyan Deng, Sonia L. Asilo, Eduardo Jimmy Quilang, Fei Zheng, Juan Du
• DOI: 10.1016/j.agwat.2026.110922

Research Groups

• State Key Laboratory of Earth System Numerical Modeling and Application, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
• Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science & Technology, Nanjing, China
• Institute of Agricultural and Biosystems Engineering, College of Engineering and Agro-Industrial Technology, University of the Philippines Los Baños, Laguna, Philippines
• MARA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
• Philippine Rice Research Institute, Science City of Muñoz, Nueva Ecija, Philippines
• International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

Short Summary

This study quantifies the differential climate sensitivity of irrigated and rainfed rice yields at the provincial level in the Philippines and projects the impact of irrigation conversion on future rice self-sufficiency under various climate change scenarios. It finds that while irrigation conversion can substantially offset negative climate impacts on yields, it is insufficient as a standalone solution to achieve high rice self-sufficiency targets, with the ratio projected to remain below 87% even with full irrigation.

Objective

• To comprehensively evaluate the adaptive potentials of irrigation conversion on Philippine food security under continuously changing climatic conditions.
• To present a climate stress benchmark of irrigated and rainfed rice yields in both dry and wet seasons using provincial-level data.
• To assess the effects of various irrigation conversion scenarios in mitigating future climate impacts on rice yields.
• To explore the plausible implications of these scenarios for national rice self-sufficiency.

Study Configuration

• Spatial Scale: Provincial level across the Philippines (81 provinces).
• Temporal Scale: Historical data from 1987–2025; future projections for the 2030s and 2050s relative to a 2022 baseline.

Methodology and Data

• Models used:
  • Panel data models linking the natural logarithm of rice yields to linear and quadratic terms of temperature and precipitation, estimated separately for irrigated/rainfed rice and dry/wet seasons.
  • Five General Circulation Models (GCMs) from CMIP6: CMCC-ESM2, GFDL-ESM4, INM-CM5–0, MRI-ESM2–0, and NorESM2-MM.
  • Three Shared Socioeconomic Pathways (SSPs): SSP1–2.6, SSP2–4.5, and SSP5–8.5.
  • Delta method for bias correction of climate projections.
  • Eight irrigation conversion scenarios (No Conversion, Historical Trend, 50%IF to 100%IF).
• Data sources:
  • Provincial-level rice area and production statistics (11,003 records: 5211 dry season, 5792 wet season) from Ricelytics (PhilRice) and the Philippine Statistics Authority (1987–2025).
  • Gridded temperature and precipitation data from the MERRA-2 reanalysis dataset (NASA Goddard Earth Sciences Data and Information Services Center).
  • Province-specific planting and harvesting dates from the RiceAtlas dataset.

Main Results

• Climate Sensitivity:
  • Dry season: Rainfed rice yields decrease by 5.6% per 1 °C warming, while irrigated rice yields decrease by 4.0% per 1 °C warming. Rainfed rice yields increase by 4.6% per 5 mm precipitation increase, compared to 1.4% for irrigated rice.
  • Wet season: Rainfed rice yields decrease by 4.6% per 1 °C warming, and irrigated rice yields decrease by 4.5% per 1 °C warming. Irrigated rice yields decrease by 2.6% per 5 mm precipitation increase, while rainfed rice shows a slight decline of 0.1%.
• Future Yield Projections (without irrigation conversion, NoCov, by 2050s):
  • SSP1–2.6: Dry season +0.77%, Wet season +0.80%.
  • SSP2–4.5: Dry season -0.89%, Wet season +0.21%.
  • SSP5–8.5: Dry season -2.06%, Wet season -1.61%.
• Impact of Irrigation Conversion:
  • Converting rainfed rice to irrigated areas substantially offsets negative climate impacts on yields.
  • Maintaining an irrigation fraction of at least 50% (SSP1–2.6, SSP2–4.5) or 60% (SSP5–8.5) can buffer against negative climate impacts on yields by the 2050s.
• Self-Sufficiency Ratio (SSR):
  • Without irrigation conversion (NoCov), the SSR is projected to decline to 77.5% (SSP1–2.6), 76.6% (SSP2–4.5), and 75.5% (SSP5–8.5) by the 2050s.
  • Even with 100% irrigation coverage (100%IF), the SSR is projected to remain below 87% in both the 2030s and 2050s across all SSPs, falling significantly short of the 98% target set by the National Irrigation Master Plan (NIMP, 2020).

Contributions

• Provides a more comprehensive, provincial-level assessment of irrigation conversion impacts compared to previous national-level studies, accounting for spatial heterogeneity.
• Integrates climate-induced yield changes into future projections, a critical factor not considered in previous national plans like NIMP (2020).
• Quantifies the differential yield sensitivity of irrigated and rainfed rice to climate variability in a real-world setting, serving as a climate stress benchmark.
• Demonstrates that irrigation conversion, while beneficial, is not a standalone solution for achieving rice self-sufficiency in the Philippines under future climate change, emphasizing the need for broader adaptation strategies.

Funding

• National Key Research and Development Program of China (Joint Research Project by DOST and MOST 2025YFE0110600)
• National Natural Science Foundation of China (42575205)
• Asian Cooperation Fund

Citation

@article{Zhang2026Potential,
  author = {Zhang, Tianyi and Lampayan, Rubenito M. and Luyun, Roger and Buela, Leunell C.M. and Deng, Nanyan and Asilo, Sonia L. and Quilang, Eduardo Jimmy and Zheng, Fei and Du, Juan},
  title = {Potential effect of irrigation conversion on rice yields and self-sufficiency in the Philippines under future climate},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110922},
  url = {https://doi.org/10.1016/j.agwat.2026.110922}
}