Impacts of Plant Spacing and Nitrogen on Wet Season Rice Yield in the Non-Saline Coast of Bangladesh

Rice is a major crop in the coastal region of Bangladesh, where Aman (monsoon) rice is predominantly cultivated. However, yields are often low due to conventional farming practices and excessive use of inorganic fertilizers. Despite this, limited research has explored the impact of precision fertilizer application and optimal plant spacing on Aman rice yield in the non-saline coast of Bangladesh. In this study, a field survey and a three-year consecutive field experiment were conducted to evaluate the impact of plant spacing and nitrogen fertilizer doses on the grain yield and yield components of Aman rice in the non-saline coastal zone of Bangladesh. The experiment involved one rice variety (BR23), five planting spacing (300, 375, 400, 450, and 500 cm(2)), and two nitrogen levels (63 and 90 kg N ha(-)(1)). The experimental design was arranged in a Randomized Complete Block Design in a factorial combination with four replications. Farmers' plant spacing varied from 1665 to 1824 cm2 with 50-60 days old 15-20 seedlings per hill for monsoon rice. Across all growing seasons, nitrogenous fertilizer did not significantly impact grain yield, but had a significant effect on plant height, straw yield. However, plant spacing significantly affected rice's yield and yield components across all seasons. The highest grain yields of 5.61, 5.42 and 5.49 t ha- 1 in 2021, 2022 and 2023, respectively were observed with the Bangladesh Rice Research Institute recommended spacing of 300 cm(2), while the lowest yield was recorded with the largest spacing of 500 cm(2). However, our findings suggest minimal effects of N fertilizer on rice yield, implying that reduced N fertilizer rates should be applied in coastal Bangladesh.