In California, avocado is primarily grown in Southern and Central parts of the state, typically in regions tempered by coastal climates and fine or course sandy loam soils. These regions face uncertain water supplies, mandatory reductions of water use, and the rising cost of water, while efficient use of irrigation water is one of the highest conservation priorities. Moreover, due to increasing salinity in water sources, effective irrigation is more critical to ensure optimal yield and high-quality avocado fruits. A two-year study was conducted in 12 mature avocado sites in California. Extensive field measurements and surveys were conducted to better understand the current water management practices, to acquire and develop relevant information on crop water use (ET) and crop coefficients, and to assess the performance of satellite-based OpenET tool for irrigation management in avocados. Surface renewal and eddy covariance equipment was used to measure actual evapotranspiration (ETa) in each site. The results illustrated considerable variability in avocado crop water consumption both spatially and temporally. The crop coefficients curves were developed for each site. Across the avocado research sites, the average seasonal crop coefficient values varied from 0.6 to 0.76. The findings demonstrated that canopy features, soil types and conditions, pruning practices, soil surface cover, and row orientations need to be considered to perform effective water management in avocado orchards. Ground shading percentage and row orientations provide a good estimation of canopy size/volume and the amount of light that it can intercept are likely the most important drivers influence crop water needs. The RMSE of the measured ETa from eddy covariance equipment and estimated ETa from Ensemble OpenET varied from 0.53 to 1.37 mm d-1. The preliminarily findings indicated that the Ensemble OpenET estimates ETa relatively well in some sites and could be an effective irrigation management tool in the future for avocado orchards, however more evaluations are required.
