Optimizing nitrogen fertilizer and planting density to improve yield and nitrogen use efficiency of dry direct seeded shaga rice in Ethiopia
摘要
Achieving high yields and quality rice tailored minimizing environmental impact is crucial for rice production in Ethiopia. However, the absence of specific recommendations for nitrogen fertilizer and planting density induce the dynamics of rice productivity and nitrogen use efficiency. The study aimed to optimize N fertilizer and planting density to enrich the growth, yield and NUE of Shaga rice. A factorial combination of three N rates (N184, N276, and N368 kg ha− 1) and planting densities (D60, D80, and D100 kg ha− 1) were presented as a randomized complete block design with three replications. Results signposted coupling of N rates and planting densities significantly affected partial factor productivity of nitrogen (PFPn), grain yield, leaf area indices, filled spikelets, number of spikelets per panicle, and biomass accumulation. The application of N rate 184 kg ha− 1 resulted in a 49.2% increase in grain yield. In contrast, increased N rate (368 kg ha− 1) led to hinder in PFPn to 8.4%. The combination of N rate 184 kg ha− 1 with the planting density of 100 kg ha− 1 yielded 6.7 t ha− 1 in Fogera, while applying 276 kg N ha− 1 with a planting density of 60 kg ha− 1 achieved 6.2 t ha− 1 in North Achefer. High N doses delayed physiological maturity by promoting vegetative growth and enhanced spikelet sterility synchronized with terminal moisture stress and low temperature during the flowering and later stage of rice and reduced PFPn. Economic analysis further revealed, the combinations of N rate 184 kg ha− 1 with planting density 100 kg ha− 1, along with the coupling of N 276 kg ha− 1 and 60 kg ha− 1 planting density, augmented net income returns of 151,456 and 137,811 Birr per hectare in Fogera and North Achefer respectively and recommended as optimal strategies to maximize profitability in rice production areas of Ethiopia.