Using canopy proximal sensors for variable rate fertilization in a Trebbiano romagnolo vineyard

The research aimed to evaluate if variable rate (VR) fertilization may be usefully adopted to reduce the amount of nitrogen application in a vineyard of cv. Trebbiano romagnolo on a flat land in the Senio valley, Italy. The NDVI values, measured with GreenSeeker® crop sensing system and yield distribution, calculated on a field representative grid, were determined in two years (2018, 2019). The vineyard maps obtained by interpolation of vigour, yield and quality parameters were subject to k-means cluster analysis to produce the delineation of homogeneous sub-field zones. The results of harvest confirmed the expected relations between the areas with highest NDVI (> 0.75) and the most productive vines. A prescription map for N fertilization was elaborated allowing to apply variable rate of nitrogen: 60 kg ha-1 of N in the lower vigour zones, 30 kg ha-1 in the higher vigour zones and no N application on missing vines and on plants affected by “Flavescence dorée” or “Esca desease”. The sustainability of vineyard management was ameliorated by saving 15 kg ha-1 of N and maintaining adequate vegetative performances across the vineyard.