Resumo

DELGADO-RAMIREZ, Gerardo et al. Estimating the crop coefficient of forage maize using remote sensing. Ing. agric. biosist. [online]. 2023, vol.15, n.1, pp.17-35.  Epub 08-Mar-2024. ISSN 2007-4026.  https://doi.org/10.5154/r.inagbi.2022.09.075.

Introduction: The crop coefficient (Kc) methodology is used to estimate actual evapotranspiration. The basal crop coefficient (Kcb) represents the potential baseline of the Kc value, and its relationship with vegetation indices calculated with spectral information is the most widely used for its estimation. Objective: The aim of this study was to estimate the Kcb of forage maize at plot level using spatially exhaustive and temporally dynamic radiometric information. Methodology: NDVI and SAVI spectral indices were estimated in two study plots. Kcb was determined using nine algorithms: six based on NDVI and three based on SAVI. Their accuracy was evaluated by comparing it with the Kcb reported in the FAO-56 Manual. Accuracy was evaluated by comparing it with the Kcb reported in the FAO-56 Manual. Results: The estimated Kcb values ranged from 0.13 to 1.12. They overestimated the FAO values at the initial stage and underestimated them at the final stage. The best evaluated algorithms were Campos KcbNDVI, showing an average relative error (ARE) of 11.6 % in the whole vegetative cycle in Plot 1, and Argolo KcbNDVI in Plot 2, with an ARE of 8.3 %. Limitations of the study: This methodology should be tested under non-standard conditions, especially those that may stress the crop or with high moisture content in the topsoil. Originality: The study showed that it is possible to estimate the Kcb of forage maize at plot level by non-invasive methods, dynamically, in a specific site and with quasi-real time monitoring of crop development. Conclusions: This methodology was found to be suitable for estimating the Kcb of forage maize due to its accuracy, practicality and availability of information for large extensions of crops.

Palavras-chave : Zea mays; satellite imagery; vegetation indices; evapotranspiration; FAO-56 Manual.