Availability on the market of small drones and low-cost digital cameras equipped with high resolution sensors have been rising the question if nutritional status of crops can be sensed through their combined application with the aim of getting information helpful for site-specific fertilization, in particular for nitrogen side-dress application. A team of researcher belonging to DiSAA and CREA-ZA, with the technical support of the Sport Turf Consulting company, explored this possibility working for two years on a maize experimental field in which different nitrogen treatment were applied. The digital camera used to take images of the field was modified by removing the IR filter and mounting a new one that excluded the red band. As consequence reflectance in the blue, green and NIR bandes could be detected. Images of the field and reference destructive measurements of aboveground biomass and its nitrogen concentration were taken at the six and nine leaves growth stages. Regression analyses between crop variables reference values and vegetation indices computed from reflectance values showed a promising predictive ability of a vegetation index based on G and NIR bands together with the fraction of soil covered by plants.
Figure: figure shows maize above ground biomass estimated by the Green Cover index.
Corti, M., Cavalli, D., Cabassi, G., Degano, L., Vigoni, A., Marino Gallina, P., 2019. Application of a low-cost camera on a UAV to estimate maize nitrogen-related variables. Precision Agriculture (2019) 20: 675-696. DOI: 10.1007/s11119-018-9609-y