Studies were undertaken on red sandy loam soil (Kandiustalf) in a semi-arid tropical climateat Bangalore (Karnataka) to find out the effect of fertilizer application in influencing oilproduction, quality and soil fertility in French basil (Ocimum basilicum). The study showedthat application of nitrogen (up to 100 kg ha-1) increased herb and essential oil yields in themain crop, first ratoon and second crop while potassium application (up to 80 kg ha-1)increased the yields in the second ratoon and second crop suggesting that soil potassiumdepletion occurred with time. Nitrogen application increased methyl chavicol (by 4.1%) anddecreased linalool (by 14.2%) contents in basil oil. Yield increases were accompanied by higherremoval of nitrogen, phosphorus and potassium from soil (by 247%, 23% and 94%,respectively) by the crop and lower amounts of exchangeable potassium (by 37.8 %) in soil.Due to the depletion of soil potassium, interactions between nitrogen and potassium weresignificant in the second crop of basil. Application of 100 kg nitrogen ha-1 and 80 kg potassiumha-1 gave optimum yield and quality of oil.