Document Type : Original Article
Authors
1 Researcher, Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
2 Associate Professor, Department of Irrigation and Development Engineering, Faculty of Agriculture and Natural Resources, University of Tehran and Faculty member of Imam Khomeini International University, Qazvin, Iran, Qazvin, Iran.
3 Professor, Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
4 Researcher, Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension
Abstract
Extend Abstract
Intouduction
Water scarcity is one of the biggest challenges facing the agricultural sector in many parts of Iran, especially in arid and semi-arid regions. Increasing agricultural water productivity is not only a solution, but also an absolute necessity. Although solutions such as increasing the area under cultivation and increasing yield per unit area, optimizing agricultural inputs, controlling population and optimizing consumption, and increasing imports have been proposed to address the challenge of food security, each of these cases has its own implementation limits (Nouri et al., 2023; Garofalo et al., 2025). Crop models are considered a valuable tool for the integrated simulation of processes affecting crop growth and for the evaluation of crop management options (Mabhaudhi et al., 2014; Wallach et al., 2019). Crop models that can accurately estimate various parameters of crop growth, soil water dynamics, crop water use and expected yield under different irrigation levels can also be a fundamental aid for the successful implementation of irrigation management practises with limited and full irrigation (Sandhu & Irmak, 2019). Therefore, the aim of this study was to calibrate and then evaluate the AquaCrop model to simulate the yield and water productivity of forage maize under furrow and tape irrigation in the arid and semi-arid regions of Iran (Alborz province). In addition, the ability of the model to simulate the yield potential of forage maize under agricultural management in the study fields was evaluated.
Methodology
The data required for this study was collected in 2016 on farms in the province of Alborz. The farms were visited in coordination with the management of the Agricultural Jihad and were examined and selected taking into account the parameters required for the study. Three farms were selected in the city of Karaj, one in the Seifabad district, one in the city of Hashtgerd and one in the village of Haji Abad. The farm in Karaj was divided into three different sections due to its larger area, different cultivation dates and different irrigation schedules. Since understanding the current situation is one of the most fundamental planning steps for evaluating and providing solutions to improve any system, this study was conducted in the form of field experiments and field farms with the aim of investigating and estimating the current status of irrigation water productivity under farmers' management, and the potential for growing forage maize in Alborz province. Water resources, the cultivated area, total irrigated land area, soil texture, soil salinity, and irrigation water salinity in each farm were investigated and measured. Additionally, some farm characteristics such as area, precise GPS location, irrigation method, irrigation water source, timing of water withdrawal and variations in withdrawal flow rate throughout the year, network type, and operator characteristics were recorded using compiled information recording forms.
Results and discussion
The results for the average yield of fresh forage corn were 49.12 tons per hectare using furrow irrigation method and 60 tons per hectare using tape irrigation method. In furrow irrigation, the highest fresh crop yield was obtained at Karaj farm (2) with 60 tons per hectare and an irrigation water productivity of 6.61 kg/m³. The lowest yield was recorded at Karaj farm (3) with 35 tons per hectare, while the lowest irrigation water productivity was at Karaj farm (1) with 4.24 kg m-³. The highest irrigation water productivity, 13.4 kg m-³, was observed at Hajiabad farm using tape irrigation. Therefore, tape irrigation is recommended for optimal water resource utilization. The study also showed that the RMSE index was 2.44 tons per hectare, and the d-agreement index was 0.947, indicating the AquaCrop model's ability to simulate corn fresh weight accurately in the study area. There was a strong correlation between simulated and measured crop yield values, with a coefficient of determination of approximately 0.95. The relative error (RE) was 3.7%, which is considered acceptable.
Conclusion
The results demonstrated that the AquaCrop model has a strong capability to analyze various management scenarios, predict performance under water-limited conditions, and optimize irrigation patterns. From a management perspective, the findings suggest that agricultural policies should shift focus from the "land productivity" index to the "water productivity" index. Additionally, providing practical training for farmers, promoting modern irrigation technologies, and utilizing simulation models like AquaCrop can play a crucial role in reducing water waste, enhancing crop yield, and ensuring sustainable production. Ultimately, implementing these strategies will not only improve water productivity but also serve as an effective step toward protecting water and soil resources and ensuring long-term food security.
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