Effect of potassium application on crop productivity in Boro rice production

An experiment was conducted on the research farm of Bangladesh Institute of Nuclear Agriculture, Mymensingh during 2007 to investigate the effect of different levels of K application on Boro rice production in Old Brahmaputra Flood Plain Soil. The soil type was Non-Calcareous Dark Grey Floodplain. The experiment was laid out in a randomized complete block design with three replications. The treatment combinations were T1, (absolute control), T2 (full dose of NPSZnB), T3 (50% of estimated K + full dose of NPSZnB), T4 (75% of estimated K + full dose of NPSZnB), T5 (100% of estimated K + full dose of NPSZnB) and T6 (K equal to estimated apparent balance + full dose of NPSZnB). The growth and yield contributing characters were significantly influenced by the treatments. For Boro rice (var. Binadhan 5), the yield attributes and the grain and straw yields responded significantly due to the treatments. The grain and straw yields of Boro rice ranged from 2.15 to 6.45 t ha-1 and 2. 80 to 8.06 t ha-1, respectively. The highest grain yield of 6.45 t ha-1 was obtained in treatment T5 (100% of estimated K + full dose of NPSZnB). A minimum replenishment of K from the soil reserve was observed. Economics of fertilizer uses for Boro rice cropping showed that among the treatments, T5gave the highest benefit cost ratio 7.58. The results indicated that in order to obtain sustainably higher crop yield under intensive rice cultivation, the addition of potash fertilizer is necessary