Researchers commonly use unplanted alleys to separate plots in experiments with paddy rice. In studies in the Philippines and Thailand we compared the performance of rice plants grown in previously cropped areas of a field with that of plants grown in areas which were unplanted alleys in the previous season. The latter plants had yields and values for several agronomic characters that were significantly different from plants grown in the previously planted areas, with yields ranging from 8 to 25 per cent higher.