The effect of nitrogen application time on Calrose rice growth and yield in south-eastern Australia

Abstract

The effects of nitrogen application time on growth and yield of rice cv. Calrose were studied in a series of three experiments between 1976 and 1980. In one experiment, in which a combine-sown rice crop received three flood irrigations prior to permanent flood, rice plant growth and grain yield were increased significantly by reducing the interval between fertilization and permanent flood. The poor response to fertilization several irrigations prior to permanent flood was attributed to nitrogen losses following sequences of nitrification and denitrification. Maximum grain yield usually occurred when fertilizer was applied at permanent flood (average of three experiments, 860 g/m2 (8.6 t/ha). Fertilization at tiliering had little effect on crop response; average yield was 8.0t/ha, while unfertilized plots yielded 7.4 t/ha. In all experiments fertilization during the period 0- 10 days after panicle elongation resulted in very rapid nitrogen uptake, leading to an average grain yield (8.3 t/ha) which approached that obtained from plots topdressed at permanent flood. Fertilization more than 14 days after panicle elongation did not significantly increase yield.