Is normalized difference vegetation index a valid indicator for nitrogen fertilization management?

Two-years field experiments were carried out to compare uniform and variable rate nitrogen fertilization in durum wheat. Satellite images were used to create fertilization maps before the second topdress fertilization. The variable rate fertilizations were applied using simple approaches based on normalised difference vegetation index (NDVI) and one combined approach based on nitrogen nutrition index (NNI). 65 kg/ha fertilizer was applied for NDVI based and uniform rates, while NNI rates were based on crop requirements. Crop production and nutrient efficiency were analyzed. Results indicated that differences between treatments in quality and quantity yield variables were not significant. However, the NNI approach showed an economic and environmental advantage.