Application of different irrigation strategies for enhancing water efficiency in wheat production using the AquaCrop model: A case study in semi-arid Morocco

Efficient irrigation practices are essential to address water scarcity and sustain wheat production in semi-arid regions. This study evaluates the performance of two distinct irrigation strategies, real irrigation and net irrigation, using the AquaCrop-OSPy (ACOSP) model to simulate the actual water requirements of wheat. The research was conducted in two experimental fields (Field F1 and Field F2) in the Chichaoua region of Morocco during the 2016/2017 and 2017/2018 growing seasons. Real irrigation supplied by the farmer in the fields revealed potential inefficiencies, such as over-irrigation and crop stress, particularly in Field F1. To address these issues, a net irrigation strategy was introduced. Net irrigation focuses on maintaining soil moisture at a level that satisfies crops' water needs without applying too much water and without stressing the plant. A threshold of 60% of total available water (TAW) was applied for irrigation scheduling under net irrigation, based on literature findings. The AquaCrop model was firstly calibrated and validated using field data, achieving high accuracy in key simulated growth parameters such as canopy cover (CC), biomass and actual evapotranspiration, with R² values ranging from 72% to 98%. These results confirm the reliability of the model for assessing wheat growth under different irrigation strategies. Significant differences were observed between the two irrigation strategies regarding irrigation quantities, yield, and water productivity. In field F1, the net irrigation approach led to slightly increased water application compared to real irrigation, rising from 369.40 mm to 400 mm in the first season and from 287.61 mm to 388.15 mm in the second season. In field F2, irrigation decreased from 490.75 mm (real) to 400 mm (net) in season 1 and from 454.46 mm to 388.15 mm in season 2. These differences highlight the model's ability to align water application with crop needs under net irrigation. Yields varied from field to field and from season to season. For field F1, yields ranged from 3.45 to 6.84 tones/ha in season 1 and from 3.85 to 7.07 tones/ha in season 2.  For field F2, yields under net irrigation showed less variability, ranging from 6.39 to 6.84 tones/ha in season 1 and from 6.59 to 7.07 tones/ha in season 2. WP was always higher under net irrigation, reaching 1.82 kg/m³, confirming that excess water applied under real irrigation did not improve crop water productivity. These findings demonstrate the effectiveness of net irrigation in accurately meeting crop water needs and reducing inefficiencies in real irrigation. This study underscores the importance of adopting efficient irrigation strategies to optimize water use and improve agricultural sustainability in semi-arid regions.