Nitrogen (N) fertilisation affects both rice yield and quality. In order to improve grain yield while limiting N losses, providing N fertilisers during the critical growth stages is essential. NDRE is considered a reliable crop N status indicator, suitable to drive topdressing N fertilisation in rice. A multi-year experiment on different rice varieties (Gladio, Centauro, and Carnaroli) was conducted between 2011 and 2017 in Castello d’Agogna (PV), northwest Italy, with the aim of i) establishing the best N fertilisation management to maximise crop yield, iii) defining a statistical method to obtain calibration functions establishing the NPI as a function of NDRE measured at PI, iv) comparing the best N management based on NDRE readings. A statistical model was developed to define dose/response curve. Results suggested different fertilisation strategies depending on the rice variety. For Gladio variety, grain yield is optimised equally splitting total N amount between pre-sowing plus tillering and PI application. Conversely, considering Centauro and Carnaroli varieties, best N management suggest reducing N application at the early growth stages, increasing topdressing N fertilisation. The algorithm also allowed obtaining calibration functions for each variety, establishing NPI as a function of NDRE values measured just before N application, with the aim of maximising grain yield. The obtained calibration functions can be implemented in variable rate application fertiliser spreader, providing an interpretative model capable of translating vigour maps into N fertiliser applications. However, calibration functions have been obtained only for Gladio, Centauro, and Carnaroli varieties, under specific environmental conditions. Further extension to other rice varieties and agro-environments is needed, and can be performed using the methodology proposed in this study, with the aim of promoting a widespread application of precision N fertilisation in rice.