Field studies have been conduced over a five-year period to examine the effect of nitrogen application on the yield and quality of essential oil in Java citronella(Cymbopogon winterianusJowitt) in a semi-arid tropical region in South India. The results showed that the yield per unit area of citronella fresh plant (herbage) differed significantly between years; the yields increased up to the second year after which time they started to decline. During the first two years, nitrogen applications up to 300 kg N/ha/year increased the oil yield significantly; however, during the third and fourth years the response to N was quadratic. This shows that it is possible to reduce the application of N after two years, while still maintaining the same content and quality of essential oil. The oil content and chemical composition of oil did not change as the age of the crop increased.