Mineral nutrition of crops along with N, P, and K fertilization decisions in cropping systems have long been based on crop yield responses to individual elements for determining the optimum rate of application of fertilizers for maximum yield. Owing to the great uncertainty for estimating or forecasting these response curve parameters, farmers often apply fertilizers in excess to avoid any risk of yield reduction. Undesirable environmental impacts have resulted from this over-fertilization. Therefore, the old paradigm based on prognosis of soil nutrient availability estimated by soil tests must be deeply questioned and reappraised for a more sustainable and efficient agro-ecosystem management. For N fertilization management, attempts have been made for reducing the uncertainty of the prognosis-based approach using the crop N balance concept but with a relatively poor success because of the difficulty in forecasting soil N supply and crop N demand in dynamic terms. A new ?plant-based diagnosis? approach of crop N nutrition using the concept of ?critical N dilution curve? and well sustained by a strong theoretical framework has been proposed. This concept has been extended successfully to a large range of arable crops. This new approach allows the monitoring of crop N status in real time by detecting if the N supply matches or not crop N demand. This in situ crop N diagnosis should help determine when and how much N fertilization is required and could be incorporated within crop N fertilization management procedures to be used by farmers. More recent research has shown that the same theoretical framework is also relevant for P, K and S crop nutrition. Along the opportunity of developing plant-based diagnosis of those three single nutrients, it provides an overall framework for developing an integrated crop N-P-K-S nutrition diagnosis for a balanced crop fertilization management. This paper introduces a special issue devoted to the development and implementation of this crop nutrition diagnosis approach. The papers in this special issue highlight the significant progress made over the last thirty years along with providing an insight and perspective of future research needs.