Effect of Different Nitrogen Levels on Growth, Yield, and Nitrogen Use Efficiency (NUE) of Hardinath Hybrid Dhan-1 in Madhesh Province, Nepal

Determining the optimum dose of nitrogen fertilizer application for hybrid rice is vital for boosting production and productivity of rice. Therefore, this study examines the effect of different nitrogen levels on the growth, yield, and nitrogen use efficiency (NUE) of Hardinath Hybrid Dhan-1 in Madhesh Province, Nepal. A field experiment conducted in 2020 at the National Rice Research Program, Hardinath, Dhanusha tested six nitrogen levels (0, 75, 100, 125, 150, and 175 kg ha-1) with four replications under Randomized Complete Block Design during rainy season (June-September). The results showed that nitrogen application significantly improved plant growth and yield, with the highest grain yield (4.99 t ha-1) achieved at 150 kg N ha-1. Increasing nitrogen beyond this level did not further boost yield, indicating that excessive nitrogen does not improve productivity. Nitrogen use and agronomic efficiency were also highest at 150 kg N ha-1, marking it as the ideal rate for optimal rice performance. Soil health, in terms of organic matter and nutrient availability, improved with higher nitrogen levels, while the highest nitrogen uptake occurred at 175 kg N ha-1. In conclusion, 150 kg N ha-1 is recommended as the optimal nitrogen level to enhance hybrid rice yield and NUE, promoting sustainable rice production in the region. These findings highlight the need for optimal nitrogen management to improve crop yield and soil properties while minimizing environmental impact.