Effect of potassium fertilization on yield and potassium nutrition of Boro rice in a wetland ecosystem of Bangladesh

摘要

Effect of potassium (K) fertilization (0, 20, 40, 60, 80 and 100kgKha(-1)) on yield, nitrogen (N) and K nutrition of Boro (dry season) rice and apparent soil K balance was studied. Experiment was conducted at Bangladesh Rice Research Institute (BRRI) regional station farm, Habiganj, Bangladesh during 2007-2008 to 2009-2010 in a wetland rice ecosystem under haor area. Cropping pattern was Boro-Fallow-Fallow. A popular rice variety BRRI dhan29 was tested in a randomized complete block design with three replications. Results indicated that BRRI dhan29 maintained an average grain yield of 5.19 tha(-1) year(-1) without K fertilization. Potassium fertilization significantly increased the grain yield to 6.86 tha(-1) year(-1). Quadratic equations best explained the progressive increase of rice yield with increasing K rates. Optimum dose of K in 3years ranged from 78 to 93kgha(-1). Internal N use efficiency of rice decreased with increasing K rates. However, K use efficiency was inconsistent. Apparent K balance study revealed that application of 100kgKha(-1) was not able to maintain a positive K balance in soil under wetland ecosystem with Boro-Fallow-Fallow cropping system. However, K fertilization decreased the negativity of K balance in soil.