Abstract
Energy and water balance assessments were caried out an unmanned aerial vehicle (UAV) in rainfed corn crop. The effects of nitrogen (N) fertilizing cover levels were analyzed for supporting precision agriculture. Strong differences in the magnitude of the energy and water balance components were perceived according to the levels of N cover fertilizations along the crop stages, but the ratios of latent (λE) and sensible (H) heat fluxes to net radiation (Rn) stabilizing with N at 200 kg ha-1. The average Rn values ranged from 4.2 MJ m-2 d-1 to 9.8 MJ m-2 d-1; for λE, the rates were from 2.0 MJ m-2 d-1 to 8.0 MJ m-2 d-1; for H from -1.2 MJ m-2 d-1 to 3.6 MJ m-2 d-1; and for G between 0.1 MJ m-2 d-1 and 0.7 MJ m-2 d-1. These values returned to different energy partitions, averaging 43 to 113% for λE/Rn, -17% to 54% for H/Rn, and 2% to 7% for G/Rn. The evapotranspiration fraction (Ef), i.e., the ratio of λE to available energy (Rn – G) and rs were taken as root-zone moisture indicators, both presenting high correlations with field measured biomass production (BIO), and productivity (Pr), with R2 above 0.90. Comparing Pr with Ef, the highest correlation when plants were with six leaves indicated that corn yield can be estimated from the modelled root zone moisture before harvest. The most important finding is that the models can be applied to estimate λE and H with high resolution aerial cameras without the thermal bands. The energy and water balance modelling demonstrated suitability for corn crop management, indicating the potential for applying these equations in other climatically suitable regions.
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Copyright (c) 2026 Dr. Teixeira A. H. de C., Dr. Loureiro D., Dr. Souza R., Dr. Cruz J., Dra Gonzaga M., Dra. Leivas J., Dra. Takemura C., Dr. Almeida A. (Author)