This study investigated the effects of irrigation, fertilizer, and forage variety on nitrogen productivity and residual soil nitrogen in Robit-Bata, Ethiopia. The experiment tested three irrigation levels (60%, 80%, 100% of available water), three fertilizer rates (manure 30 t/ha, urea 100 kg/ha, urea 300 kg/ha), and seven forage varieties (ILRI-16791, ILRI-16803, ArekaDZF590, ILRI-10871, ILRI-6765, ILRI-75 and ILRI-140). Data was collected over two irrigation seasons (2021 & 2022) and three rainy seasons (2020, 2021 & 2022). All the collected data were organized by MS Excel and subjected to ANOVA analysis using SPSS software, at a significance level of 5%. Mean comparisons for interaction effects were tested by using Minitab software. The highest dry matter yield (8.7 t ha-1), nitrogen uptake (131.2 kg N ha-1) nitrogen use efficiency (46 kg kg-1), and lowest nitrogen surplus (18.9 kg N ha-1) were observed under full irrigation (I100) treatment. However, the difference with deficit irrigation (I80) was not significant (P>0.05). ILRI-16791 with urea at 300 kg ha-1 exhibited the highest dry matter yiled (20.7 t ha-1) and nitrogen uptake (259.2 kg ha-1). However, the highest nitrogen use efficincy (138.8 kg kg-1) and lowest nitrogen surplus (-168.8 kg ha-1) were observed for ILRI-16791 with urea at 100 kg ha-1. In the rainy season, the three-way interaction effect of forage variety, fertilizer rate/types, and year was significant. Similar to irrigation season the highest dry matter yiled (50.7 t ha-1) and nitrogen uptake (760.5 kg ha-1) were recorded for ILRI-16791 with urea at 300 kg ha-1 in 2021 rainy season. Again, the lowest nitrogen suplus (-640.7 kg ha-1) occurred for ILRI-16791 with urea at 100 kg ha-1 in the 2021 rainy season. The interaction effects of fertilizer rate and irrigation levels on residual soil nitrogen were significant for the top 30cm soil layer. The highest residual soil nitrogen (117.2 kg ha-1) was observed for I60 with urea at 300 kg ha-1. ILRI-140 with urea at 100 kg ha-1, resulted the high residual soil nitrogen in rainy season. Generally, applying deficit irrigation (I80) with urea at 100 kg ha-1 for ILRI-16791 is recommended as an appropriate management practice for reducing inputs while achieving high resource use efficiency, forage quality, economic benefits and reduce environmental impact without compromising the dry matter yield. Additionally, using legume forages, especially ILRI-140 with low urea, can improve residual soil nitrogen, particularly during years like 2021 with favorable rainfall. Economic analyses comparing irrigation and fertilizer strategies, and exploring reduced urea with manure for ILRI-16791 are recommended for future research to guide farmers towards cost-effective and sustainable practices. Keywords: Irrigation, dry matter yield, nitrogen use efficiency, nitrogen uptake, nitrogen balance, residual soil nitrogen.