Bahathy et al. (2026) Optimizing Irrigation Scheduling for Major Crops in the Middle of Iraq using the CROPWAT Model to Promote Sustainable Agriculture

Identification

• Journal: Current Applied Science and Technology
• Year: 2026
• Date: 2026-04-10
• Authors: Idrees A. Al Bahathy, Sahar fadhil saadoun, Hawraa Neamah Hussein, Zahraa Zahraw Al-Janabi
• DOI: 10.55003/cast.2026.268250

Research Groups

• College of Engineering, AL-Qasim Green University, Babylon, Iraq
• College of Environmental Sciences, AL-Qasim Green University, Babylon, Iraq
• Environmental Research Center, University of Technology- Iraq, Baghdad, Iraq

Short Summary

This study optimized irrigation scheduling for wheat, barley, and rice in Iraq's Al-Qadisiyah Governorate using the FAO CROPWAT 8.0 model, revealing that rice, a summer crop, requires significantly more irrigation water than winter crops due to seasonal climatic variations. The research provides precise irrigation schedules to enhance water conservation and promote sustainable agriculture in a water-scarce region.

Objective

• To determine the optimal irrigation scheduling and water requirements for wheat, barley, and rice in the Al-Qadisiyah Governorate, central Iraq, using the CROPWAT model to reduce water consumption and address water scarcity.

Study Configuration

• Spatial Scale: Al-Qadisiyah Governorate, central Iraq (approximately 180 km southeast of Baghdad, between 31° 51′ 0″ N and 45° 3′ 0″ E).
• Temporal Scale: Climatic and crop data for the year 2022, with monthly climatic data used for calculations. Crop growing seasons span winter (wheat, barley) and summer (rice).

Methodology and Data

• Models used:
  • FAO CROPWAT 8.0 model: Used to calculate crop water requirements (CWR), irrigation water requirements (IWR), and irrigation schedules.
  • FAO Penman-Monteith-Equation: Employed by CROPWAT to compute reference evapotranspiration (ETo).
  • CLIMWAT: Meteorological database used by CROPWAT for climatic data.
  • USDA S.C. methodology: Used for calculating effective rainfall.
• Data sources:
  • Iraqi Ministry of Agriculture website: Source for crop and climate data for the year 2022.
  • Climate 2.0 database: Provided monthly climatic data.
  • Soil type: Determined as black clay (based on Ewaid et al., 2019).
  • Climatic variables: Minimum and maximum temperatures (°C), amount of rainfall (mm), duration of sunshine (hours), wind velocity (km/day), and relative humidity (%).

Main Results

• Reference evapotranspiration (ETo) in Al-Qadisiyah Governorate peaked in July at 2.83 mm/day and reached its lowest in January at 0.82 mm/day.
• Effective rainfall values for the crops were 23.2% for wheat, 26.3% for barley, and 0% for rice, indicating temporal variation with higher amounts in winter.
• The total irrigation water requirements were 99.1 mm for wheat, 103.1 mm for barley, and 404.1 mm for rice.
• Rice, a summer crop, exhibited significantly higher irrigation water needs compared to winter crops like wheat and barley, primarily due to higher temperatures, less rainfall, and increased evapotranspiration during its growing season.
• Irrigation demand for crops generally decreased during the initial growth phase, increased during the developmental period, remained stable and peaked during the intermediate phase, and declined in the later phase to facilitate harvesting.
• Rice required more frequent irrigation periods than wheat and barley due to the lack of rainfall during its summer planting season.

Contributions

• Developed and presented optimal irrigation schedules for major crops (wheat, barley, and rice) in the Al-Qadisiyah Governorate, Iraq, using the FAO CROPWAT 8.0 model.
• Quantified the specific crop water requirements and irrigation needs for these crops in a water-stressed region, providing crucial data for water resource management.
• Demonstrated the utility of CROPWAT and CLIMWAT as effective scientific tools for assessing crop water requirements and improving irrigation scheduling, thereby promoting water conservation and sustainable agricultural practices in Iraq and globally.
• Offered practical guidance for farmers to optimize water use, reduce waste, and mitigate the impacts of water scarcity in arid and semi-arid regions.

Funding

Not explicitly stated in the provided text.

Citation

@article{Bahathy2026Optimizing,
  author = {Bahathy, Idrees A. Al and saadoun, Sahar fadhil and Hussein, Hawraa Neamah and Al-Janabi, Zahraa Zahraw},
  title = {Optimizing Irrigation Scheduling for Major Crops in the Middle of Iraq using the CROPWAT Model to Promote Sustainable Agriculture},
  journal = {Current Applied Science and Technology},
  year = {2026},
  doi = {10.55003/cast.2026.268250},
  url = {https://doi.org/10.55003/cast.2026.268250}
}