Response of wetland rice to potassium in farmers’ fields of the Barind tract of Bangladesh

Six trials were conducted in the dry and wet seasons on potassium (K)‐deficient Barind soils (Aeric Haplaquept) to evaluate the response of rice to potassium (K) fertilizer. The application of 30 kg K ha‐1 significantly increased rice grain yields at all the test locations. In some cases, grain yield increased consistently up to 120 kg ha‐1 of applied K. Rice yield responded quadratically to K application. The calculated maximum K doses were 114 kg ha‐1 for the dry season and 165 kg ha‐1 for the wet season. The calculated optimum doses of K application were 100 kg ha‐1 and 147 kg ha‐1 for the dry season and wet season, respectively. Application of K fertilizer increased K content only in the straw, but not in the grain. The K use efficiency of wetland rice at 30 kg K level was 16.7 kg grain kg‐1 applied K in the dry season and 10.0 to 33.3 kg grain kg‐1 applied K in the wet season. The K uptake by rice was higher in the dry season than in the wet season. The average apparent K recovery at 30 kg K ha‐1 application level was 59%, which decreased gradually with an increase in the K dose.