PT  - JOURNAL ARTICLE
AU  - Gatti, Matteo
AU  - Squeri, Cecilia
AU  - Garavani, Alessandra
AU  - Vercesi, Alberto
AU  - Dosso, Paolo
AU  - Diti, Irene
AU  - Poni, Stefano
TI  - Effects of Variable Rate Nitrogen Application on cv. Barbera Performance: Vegetative Growth and Leaf Nutritional Status
AID  - 10.5344/ajev.2018.17084
DP  - 2018 Jul 01
TA  - American Journal of Enology and Viticulture
PG  - 196--209
VI  - 69
IP  - 3
4099  - http://www.ajevonline.org/content/69/3/196.short
4100  - http://www.ajevonline.org/content/69/3/196.full
SO  - Am J Enol Vitic.2018 Jul 01; 69
AB  - Variable rate application of vineyard inputs in field parcels characterized by different levels of vigor and/or yield is one of the most promising applications of precision agriculture. In a four-year study, we provided ground-truthing of three different vigor levels (L = low, M = medium, and H = high) derived pre-trial from Normalized Difference Vegetation Index (NDVI) values determined by remotely sensed imagery (5 m pixel resolution) in a small Barbera vineyard (0.64 ha). Each vigor level was subjected to three fertilization strategies (S) consisting of no N supply (C, 0 kg/ha), standard supply (S, 60 kg/ha), and variable-rate application (VRA) delivering 0, 60, and 120 kg/ha to H, M, and L vines, respectively. Post-trial effects were assessed by taking another NDVI satellite image at the same resolution and by adding proximal sensing performed with the MECS-VINE sensor yielding the estimation of a canopy index (CI). Ground-truthing was based on recording main vine growth parameters and leaf nutritional status. Results show that vine balance of L vines was optimal. Variability among vigor levels was significantly reduced in years 3 and 4, while mean effects related to fertilization strategy were not significant and very few S × V and S × Y interactions were found. However, when the ground-truthing assessment was compared with the CI index values, it was very clear that VRA was able to reduce variability among vigor levels (CV = 1.42%) versus standard fertilization at 60 kg/ha (8.20%).