Three separate experiments were conducted in the nursery using grassland soil as a growing medium. The first experiment was conducted to assess the nodulation of the two legume trees grown in unamended soil, the second was done to determine the effects of N-fertilizer application on the interaction of the five Rhizobium isolates with A. falcataria and the third experiment was conducted to determine the effects of liming on the Rhizobium x A. mangium interaction.Three local Rhizobium isolates, Al6 , A~8, and Al4 were effective for A. falcataria with Ai6 as the most promising strain under the conditions described. In general, application of combined nitrogen suppressed nodulation of A. falcataria. Nodulation in the absence of combined N exceeded those fertilized with 30kgNha ~by 114.0%,60kgNha Jby209.6% and 100kgNha ~by237.1% .Two local isolates, Amt0 and Am2, and an introduced strain, NA 1533 from Australia were promising for A. mangium. Unlike in A. falcataria, the application of combined nitrogen at the rate of 100 kg N ha-~ did not suppress nodulation in A. mangium. Liming the soil to pH 6.5 regardless of nitrogen fertilizer application improved the performance of the Rhizobium-A. mangium symbiosis.