The most significant staple food crop in the world for more than half of the world's population is rice (Oryza sativa L.). Globally, the production of rice uses between 9 and 10 million tonnes of nitrogen fertilizer annually (Nayak et al., 2022). But only 30 to 40 percent of the N that is applied is retrieved by the crop, leading to significant reactive N losses that not only deplete the national coffers but also contaminate the environment. Improving N use efficiency in crop production systems requires a synchrony between crop demand and N supply from all sources throughout the growing season (Ladha et al., 2000). Site-specific N management is one of the most sophisticated N management techniques available; in more than 100 field tests conducted throughout Asia, it increased the N-use efficiency of irrigated rice by 30–40% and grain yield by 7% (Dobermann et al., 2002). According to Dobermann and Cassman (2004), it can be either prescriptive, corrective (real-time N management) or a combination of the two. Real time nitrogen management is a fast way to measure the amount of nitrogen in leaves. It is sensitive to changes in crop N demand during the growing season and is directly correlated with photosynthetic rate and biomass production. The right rate, right time, right place and right product are the four guiding principles that help you optimize soil nutrient supply over time and space to meet crop needs.