Estimation of canopy cover, biomass, asparagus (Asparagus officinalis L.) spear yield, and the need for irrigation using AquaCrop model

Water is the main factor for crop growth and development. Globally irrigation in agriculture uses about 70% of the available freshwater resources, and thus improving irrigation management will increase the water use efficiency. Intensive agriculture with perennial crops like the asparagus (Asparagus officinalis L.) in the semi-Arid environment of Sonora in northwestern Mexico consumes significant volumes of water. These crops receive around 2,000 mm annually of irrigation to reach commercial asparagus spears yields (8.5 to 10.5 t ha-1). In this study, the AquaCrop model was parameterized and evaluated to estimate canopy ground cover (CC), the amount of crop biomass produced (B), the asparagus spears yield (Y), and the need for irrigation for growing seasons (2019 and 2020). Results showed good accuracy for CC and B according to the root mean square errors (RMSE) from 2.3 to 10.35% CC and 3.25 to 4.48 t ha-1 B, between model predictions and observed data. In addition, the simulated asparagus spears yield was 8.85 to 9.22 t ha-1 for respective growing seasons. Therefore, the net irrigation for the crop under these conditions was around 1300 to 1400 mm per growing season. This lets to achieving a reduction of around 600 mm (more than 30%) of water per season compared to the current irrigation amount applied by the growers. Overall, results have shown that the AquaCrop model is suitable for CC, B, Y, and net irrigation estimation for asparagus cultivar Atlas in the arid environment of Sonora in northwestern Mexico.