Spatio-temporal monitoring of soil and plant indicators under forage cactus cultivation by geoprocessing in Brazilian semi-arid region

The objective of this work was to characterize the spectral responses of soil and plant indicators utilizing the Soil-Adjusted Vegetation Index (SAVI) and Leaf Area Index (LAI) in areas under the cultivation of ‘Orelha de Elefante Mexicana’ forage cactus (Opuntia stricta (Haw.) Haw.) and ‘Miúda’ (Nopalea cochenillifera (L.) Salm-Dyck) in Brazilian semi-arid region and to establish a model for characterizing vegetation cover in crop production areas. The research was conducted in Brazilian semi-arid region, which had two areas under the cultivation of forage cactus in the period from 2017 to 2020. Soil physical attributes and plant morphometric variables were recorded, concomitantly the determination of SAVI and LAI, from images from the Sentinel-2 satellite. The recorded data were submitted to principal component analysis. The cumulative total variance of the principal components showed satisfactory results for both areas. There was a correlation between plant height, the number of cladodes, and vegetation indices, selected to compose the predictive variables of the multiple regression model. It is recommended to use images from the Sentinel-2 satellite in small areas, given its lower spatial resolution in capturing different spectral responses.