Sinde González, ÍzarGil Docampo, María de la LuzArza García, MarcosGrefa Sánchez, JoséYánez Simba, DianaPérez, PatricioAbril Porras, Víctor Hugo2021-05-072021-05-072021International Journal of Applied Earth Observation and Geoinformation, 101 (2021), 1023550303-2434http://hdl.handle.net/10347/26138Pastures account for more than 56% of the total agricultural area of Ecuador and constitute the main food source for livestock. Hence, the agile, affordable, and reliable quantification of aboveground biomass (AGB) is an essential task in grazing utilization and management. In this paper, a method to estimate the AGB via aerial photogrammetry with a low-cost UAV multirotor is proposed. Digital terrain models and crop surface models were generated from data captured during two flights at different times, and the volume between them was calculated. An empirical relationship between volume and dry biomass was obtained by harvesting and weighing some samples and deriving a density factor (DF). The method was tested over 54 plots with different types of forage under differential fertilization treatments. Fertilized annual ryegrass exhibited the best growth and highest biomass (2632 kg/ha). The estimation and calculation of the crop volume via UAV-based photogrammetry saves time and generates notably precise (R2 = 0.78) information on the dry biomasseng© 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)Atribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/Cultivated pasturesCSMPrecision agricultureDTMAboveground biomassjournal article10.1016/j.jag.2021.102355open access