Nitrogen Use Efficiency of Modern Rice Variety Influenced by Integrated Nutrient Management Options in Dry Season

Abstract

Nitrogen (N) is the most limiting nutrient element affecting yield and performances of modern rice varieties. However, efficient use of nitrogen by a modern rice variety might be improved through integrated fertilizer management options. To explore this, a field experiment was conducted over two consecutive dry seasons (2021-22 and 2022-23) from December to June at the experimental field of Sher-e-Bangla Agricultural University (SAU), Dhaka, Bangladesh. Modern rice variety, BRRI dhan100 was used in the experiment. The objectives of the experiments were to investigate the responses of BRRI dhan100 under different N fertilizer rates as well as to assess N use efficiencies of the variety. The experiment comprised seven treatments such as N₁= Researcher’s Practice (RP): N-P-K-S- Zn @ 124-22-75-20-4 kg ha^-1, N₂ = N₁ + 33% more N over N₁, N₃ = N₁ – 33% less N than N₁, N₄ = N₁ but no nitrogen was used (-N), N₅ = N₁ + Cowdung @ 5 t ha^-1, N₆ = Soil test based (STB) dose: N-P-K-S-Zn @ 130-20-83-21-3 kg ha^-1 and N₇ = Absolute control (No fertilizers applied). The experimental design was RCB (randomized complete block) with three replicates. Standard management practices were maintained across treatments. Yield and yield components data were collected following standard methods at maturity. Collected grain and straw samples were analyzed to estimate N use efficiencies. The treatments had significant (p<0.01 to 0.05) effects on yield, yield components, and N use efficiencies of BRRI dhan100 in both years. Among the treatments, N₁, N₅ and N₆ showed statistically similar performances of BRRI dhan100 in respect of yield, yield components and nitrogen efficiencies. Irrespective of years, the highest mean grain yield (6.76-6.83 t ha⁻¹) was obtained from N₅ (N₁ + Cowdung), which were statistically identical with those in N₁ (Researcher’s Practice: RP) and N₆ (STB) but significantly (p<0.01) higher than other four treatments (N₂, N₃, N₄ and N₇).  N use efficiencies of BRRI dhan100 were significantly (p = 0.01) affected by the treatments. Agronomic (AE_N: 21.63 to 23.98 kg grain kg^-1 applied N) and physiological efficiencies (PE_N: 36.99 to 40.36 kg grain kg^-1 N uptake) of N₁, N₅ and N₆ were statistically identical but significantly (p<0.01) higher than that in N₂ and N₃. Therefore, considering overall performances especially grain yield and nitrogen use efficiencies, BRRI dhan100 may be grown applying the fertilizer treatments N₁ (Researcher’s Practice: RP), N₅ (N₁ + 5 t ha^-1 Cowdung) and N₆ (STB) to achieve higher yield, improve N use efficiencies ensure food security of the country and expectantly to maintain soil health.

Bangladesh Rice J.29(2): 35-45, 2025