Response of hybrid rice (Oryza sativa) to nitrogen and potassium application in sandy clay-loam soils

A field experiment was conducted during the rainy seasons of 1998 and 1999 to study the productivity and economics of hybrid rice (Oryza sativa L.) as influenced by nitrogen and potassium application. The experiment was laid out in split-plot design with 2 levels of nitrogen, viz 100 and 200 kg/ha, in main plots and 2 levels of potassium, viz 62.5 and 125 kg K/ ha, applied full dose at transplanting, half at transplanting + half at maximum tillering and one-third at transplanting + one-third at maximum tillering + one-third at panicle emergence in subplots. One absolute control was kept with main plot as well as in subplot treatments along with 3 replications. An application of 200 kg N/ha significantly increased the plant height (126.8 and 127.9 cm), total number of tillers (16.2 and 16.3), dry-matter accumulation (15.6 and 16.3 tonnes/ha), grain and straw yields (6.5 and 9.5 tonnes/ha based on pooled data) of hybrid rice, while 100 kg N/ha resulted in highest benefit : cost ratio of the crop. Significantly higher total number of tillers (14 and 14.5), dry-matter accumulation (14.3 and 15.0 tonnes/ha) and grain yield (5.8 and 6.1 tonnes/ha), straw yield (8.5 and 8.9 tonnes/ha) and benefit:cost ratio of the crop were recorded with the application of 62.5 kg K/ha when applied in 2 equal splits, (halt at transplanting + half at maximum tillering).