Cuantificación de biomasa en pasturas a partir de imágenes tomadas por drones

In pastoral production systems, to increase the efficiency of both the pasture and the animal, it is necessary to systematically monitor pasture growth and availability. The drone in these systems can speed up and increase the amount of information useful for making decisions. For this reason, the main objective of this work is to evaluate the height measurement and biomass estimation of sown pastures through the analysis of images taken by drones. The evaluations were carried out on a second year fescue pasture located at the Centro Regional Sur (CRS) belonging to the Agronomy Faculty of the Universidad de la República, Uruguay. In the evaluation process, 4 activities were carried out simultaneously: calibration of ruler and RPM for the pasture under study, analysis of images obtained by drones, as well as the creation of a methodology to obtain biomass from images and field data (ruler and/or RPM), and the comparison between measurement methods. The results obtained for the calibration of ruler height and RPM with the available biomass, achieved adjustments with an R² of 0.5241 and 0.5423 respectively.

 The DJI Mavic 2 Pro drone was used, which has a UHD camera (ultra HD 5472 x 3648) and flights were made at 60 and 100 meters for the creation of orthomosaics. It was based on taking biomass heights with ruler and RPM in a few georeferenced points in the field and applying a supervised classification (CS) on the generated orthomosaic. Regarding the relationship between the biomass in (kgMS/ha) obtained with the CS using the ruler or RPM and adjusting for the percentage of bare soil (SD), compared to the biomass obtained using 75 measurements of pasture height with ruler or RPM, they achieved adjustments of R²: 0.84 and 0.92 with ruler and of R²: 0.57 and 0.46 with RPM, for flight heights of 60 and 100 m respectively. This work also allowed us to consider a series of advantages and disadvantages that involve the use of drones at present, based on what has been observed in the development of the activity.