The distribution of the roots of any crop is an important tool for their management, especially in relation to the amount of water to be applied and also the amount of fertilizer. In fertigation there is a specific feature in that water and fertilizers are applied in a concentrated area, which features a unique situation that requires studies to better conduct the crop. This research project was aimed at evaluating the development of the Citrus roots in a fertigated system. An experimental work was conducted in the city of Reginópolis-SP/Brazil, using ‘Valencia’ trees, grafted on citrumelo Swingle rootstock. The treatments consisted of five rates of N and K, applied through fertigation: T1 - control (no nutrient), T2 - 25%, T3 - 50%, T4 - 100% and T5 - 200% of N and K. The 100% rate, officially recommended, was established based on historical of soil and leaf analysis and also in accordance with the expected productivity. The remaining rates were calculated from it. There were two samples: before the beginning of the fertigation, in September, and during the fertigation, in January. Three plants were chosen in each treatment and in each plant were made six sampling at four depths (20, 40, 60 and 80 cm depth). In general, the density of root length was higher in the second sampling, during the irrigation. It was observed that regardless of the type of management adopted, the root length density decreased with increasing sampling depth. The highest values of root length density were found at 20 cm deep. At sampling right below the dripper, the root length density decreases with increasing dose of fertilizer.