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A field experiment was conducted on an aridisol in Pali Forest Division of Western Rajasthan to study the influence of different nitrogen (0. 9 and 18 g N per tree as urea) and phosphate (0, 3 and 6 g P2O5 per tree as single superphosphate) levels on growth and biomass production of Ailanthus excelsa, N18P3 (18 g N + 3 g P2O5 per tree) was the optimum level and increases tree height by 49%, 85% and 35% at one, two and three years of age; collar circumference by 56%, 101% and 11% and crown diameter by 47%, 63% and 58%, respectively, at three ages. Increase in total biomass production due to this treatment was 181% at one year and 185% at two year of age. Magnitude of response was higher due to nitrogen application. Combined application of N and P had synergistic influence and enhanced the growth, leaf area and root growth of trees.