Abstract

Highly soluble N fertilizers like urea may be lost from the soil plant system through leaching, ammonia (NH3) volatilization and denitrification that reduce NUE and Yield. The study was conducted to determine the effects of UREA^Stabil on enhancement of nitrogen utilization efficiencies of rice crop and to evaluate the influence of UREA^Stabil on growth and yield of rice under waterlogged conditions of Fogera area. The treatments set up were comprised Control, recommended N from conventional urea (as basal & tillering), recommended N from UREA^Stabil fertilizer applied once as basal, recommended N from UREA^Stabil (split as basal and tillering), half below the recommended N from UREA^Stabil as basal, half more than the recommended N from UREA^Stabil (split as basal and tillering), half more than the recommended N from conventional urea (split as basal and tillering), half more than the recommended N from UREA^Stabil as basal. Data were collected plant height, total tiller number, panicle length, number of fertile grains, thousand seed weight, grain yield, straw yield and harvest Index. Economic analysis was performed by following CIMMYT (1988) partial budget analysis methodology. Highly significantly (P<0.01) affected grain yield (3.55 t ha^-1) was recorded on 136.5 kg N ha^-1 in split application 45.5 kg N ha^-1 as basal and 91 kg N ha^-1 tillering stage from UREA ^Stabil source. From the conventional urea source of N, the application of 136.5 kg N ha^-1 in split application (45.5 kgha^-1 as basal and 91 kgha^-1 tillering stage was provided higher yield (3.14) which is statistically non-significant compared to slow-release fertilizer. The economic analysis has further revealed that application of 136.5 kg N ha^-1 from UREA ^Stabil in split application of 45.5 kg N ha^-1 as basal and 91 kg N ha^-1 tillering stage provided highest net benefit of Birr 47,356 ha^-1 was the most profitable treatment for lowland rice production. Slow release UREA ^Stabil nitrogen fertilizer enhances nitrogen use efficiency by reducing denitrification, leaching and ammonia volatilization. Application of 136.5 kg N ha^-1 rate from the source of UREA ^Stabil in split application of 45.5 kgha^-1 as basal and 91 kg N ha^-1 tillering stage is the best to be recommended for lowland rice production of Fogera and similar agro-ecologies in Ethiopia.