The study reports the effect of residual nitrogen on the yield of rice crop after removal of Acacia nilotica (L.) wild. ex. Del. tree in a traditional agroforestry system in central India. Twenty four homogeneous rice fields were selected. These were divided into six sets of four fields each. From these sets, trees had been removed, 1-5 years and 7 years, respectively before the beginning of the study. There was only one tree stump in each field. Rice crop and soil were sampled at 1-4 m and 20 m distance from the tree stump. Distance at 20 m was treated as control. Maximum 53% of the residual nitrogen was released quickly for the first rice cropping season following the tree removal and remaining 37% gradually, until the fifth cropping season. Yield of the rice crop was higher by 73%, across the distances, for the first cropping season, 52% for the second, 45% for the third, 41% for the fourth and 26% for the fifth cropping season, compared to the control. The crop yield, soil organic C and total soil N increased up to 5 m from the tree stump in the first cropping season. By the fifth cropping season, the increase due to tree removal was confined to 2 m from the stump. Total increase in the crop yield, across the cropping seasons, was 12.5 t ha(-1) which was nearly equal to the reduction in the crop yield suffered during 15 years of the tree growth. Soil organic C and total soil N declined with the passage of time following the tree removal, where as C/N ratio increased.
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