EJSSEurasian Journal of Soil ScienceEurasian J Soil Sci2147 - 4249Federation of Eurasian Soil Science Societieshttp://ejss.fesss.org/10.18393/ejss.119819010.18393/ejss.1198190Yield response of rice (Oryza sativa L.) to elevated potassium applied under the irrigated ecosystem of BangladeshMd Zakir Hossain Md Mahfuzur Rahman mmahfuz.edu.bd@gmail.comMd Niaz Morshed Md Eftekhar Uddin Md Hasibur Rahaman Hera Naznin Sultana Md Abul Hashem 122104 - 1102022-03-112022-10-252022-11-022023-04-01 Copyright © 2016 The authors and Federation of Eurasian Soil Science Societies A field experiment was conducted at Bangladesh Agricultural University farm, Mymensingh, Bangladesh, during the Boro season, 2017 with six different K fertilizer rates: 0, 10, 20, 30, 40 and 50 kg ha-1 to determine the optimum rate of potassium (K) fertilization for the improved yield of a specific rice variety in the irrigated ecosystem under floodplain area. Compared with no K fertilizer, adding K increased the rice grain and straw yields significantly, with all other yield contributing components, except 1000-grain weight. The highest yield of grain (7.07 ton ha-1) and straw (8.48 ton ha-1) were recorded in recommended fertilizer dose (RFD) of NPS + 50kg K treatment, which were statistically identical with RFD of NPS + 40 kg K. Rice grain and straw yields due to the different treatments increased by 18.65% to 53.74% and 18.67% to 53.78%, respectively over control. K content and uptake through grain and straw were significantly influenced by applying different levels of K. These results specified that the use of 40 kg K ha-1 had better performance on the grain and straw yields. Therefore, we conclude that the application of 40 kg K ha-1 along with the RFD of NPS for BRRI dhan29 cultivation is the best option for higher yield in Old Brahmaputra Floodplain soil.Boro rice, floodplain, irrigated ecosystem, potassium, yield.