Remote Sensing: Assessing the differences between NDVI obtained in spring and autumn, in a mountain olive grove

Abstract: By providing a set of tools that allow the acquisition and processing of spatial data, Geographic Information Technologies (GIT) facilitate monitoring and management of olive parcels and enable precision olive growing, even in traditional mountain olive groves. The use of unmanned aerial vehicles (UAV) with multispectral cameras, for acquisition the geospatial data of terrain surface and the feature on its surface, allows monitoring the crop phenology evolution, as well as the differences between various phenological phases. In 2018 campaign, we used UAV, multispectral cameras, and photogrammetry software for drone mapping -Pix4D in a traditional mountain olive grove, whit 22.5 ha in Figueira de Castelo Rodrigo, during the project “Promoção e Valorização de Azeites de Montanha” (CENTRO-01-0246-FEDER-000004/6756). The data were processed with a set of tools for processing spatial data in ArcGIS software, which allowed analyze the differences between the Normalized Difference Vegetation Index (NDVI) obtained in two distinct phenological phases: at flowering (spring) and at harvest (autumn). The results showed us significant interzonal differences and between seasons, (spring: -0.49-0.74 and autumn: -0.08-0.96). That allowed us to identify less vigorous and problematic areas, which need greater attention and investment by the farmer and the practice of other techniques, such as, for example, soil analysis and the corresponding fertilization advice. By focusing the investment only on areas identified as being weakened or less productive, this will allow the farmer using treatments that are more effective and reduce production costs.