Nitrogen use efficiency in wheat through integrated fertilizer management in Eastern Amhara, Ethiopia

Excessive nitrogen fertilizer application often results in disproportionately high nitrogen losses relative to yield gains. Therefore, this study, conducted in 2024, evaluated wheat nitrogen use efficiencies under integrated applications of mineral nitrogen and vermicompost. The experiment consisted of four nitrogen levels (0, 34.5, 51.75, and 69 kg N ha⁻1) and three vermicompost (VC) levels (0, 3.52, and 7.04 t ha⁻1), arranged in a factorial randomized complete block design (RCBD) with three replications. Data were analyzed using R software, and mean separation was performed using Duncan’s Multiple Range Test (DMRT) at a 5% probability level. Results showed that the main and interaction effects of N and VC significantly (P < 0.05) influenced wheat harvest index (HI), agronomic use efficiency (AE) and partial factor productivity (PFP). The highest HI (49.76 ± 0.65) was obtained from the combined application of 69 kg N ha⁻1 and 7.04 t VC ha⁻1, whereas the lowest HI (38.10 ± 0.36) was recorded under the control treatment. The maximum agronomic use efficiency (AE), 37.05 kg kg⁻1, was achieved with 3.52 t VC ha⁻1 alone, while the lowest AE (21.31 ± 0.69 kg kg⁻1) occurred under the application of 69 kg N ha⁻1 + 3.52 t VC ha⁻1. Similarly, the highest partial factor productivity (PFP), 207.9 ± 4.97 kg kg⁻1, was recorded under 3.52 t VC ha⁻1 alone, whereas the lowest PFP (42.99 ± 0.54 kg kg⁻1) was obtained from 69 kg N ha⁻1 + 7.04 t VC ha⁻1. Overall, AE, PFP, and physiological efficiency (PE) declined as the nitrogen rate increased. To improve wheat yield and nitrogen use efficiency, optimizing the timing and method of nitrogen application is more effective than simply increasing the fertilizer rate. Further research across multiple locations and years on permanent plots is recommended to validate these findings and assess residual effects on soil fertility and wheat productivity.