Citrus is one of the premier fruit crops, potentially a promising source for providing nutritional security, since staggering 900 million people are globally proclaimed to be under-nourished. In most of the perennial crops like citrus, identifying nutrient constraints in standing crop and addressing them within the same growth period warrants a truly complex exercise to implement effectively. Effect of nutrients on plant growth and development has been studied for over 350 years since the experiments of van Helmont in 1648. Exciting progress has been made in the past 50 years to develop and improve diagnostic techniques of identifying nutritional constraints in order to define the fertilizer requirement. Diagnostic tools of nutrient management such as leaf analysis, soil analysis , juice analysis, to some extent biochemical analysis and at times sap analysis , all have been under continuous critical scrutiny and recurrent use. It is abundantly clear that no one of these alone is capable of addressing the nutritional problem of current standing crop with the exception of combined use of leaf and soil analysis having comparatively some added advantages with respect to their application in field.