Increasing the demand and its productivity of lowland rice in Fogera Plain of Ethiopia is crucial. The productivity of lowland rice in Fogera Plain is however low mainly due to poor soil nitrogen management systems. One way to deal with this challenge is using improved nitrogen management practices. The main objectives of this study was (1) to quantify nitrogen fertilizer rates and its method of applications for increasing the productivity of rain-fed lowland rice in Fogera Plain; (2) to determine the optimum nitrogen use efficiency of rain-fed lowland rice in different placement systems; (3) to determine the proper time of applying different nitrogen fertilizer sources to rain-fed lowland rice in different application methods; and (4) to identify the best nitrogen fertilizer source(s) for rain-fed lowland rice varieties in Fogera Plain. Three field experiments were conducted for two years during the main cropping seasons of 2017 and 2018 in Fogera Plain. Chapters 2 (two levels of N application methods by six N rates of fertilizer and the control) and 4 (three N sources of fertilizer by three rainfed lowland rice varieties) were conducted using a factorial arrangement laid out in a Randomized Complete Block Design (RCBD) in three replications while Chapter 3 (six, one and three N sources, methods and time of applications as conventional Urea, Urea supergranule and slow-release Urea, respectively) was laid out in RCBD in three replications. The variable/parameters considered during the study were growth and yield parameters for all experiments. Leaf area index and soil-plant analysis development (SPAD) value at flower initiation growth stage were taken as physiological parameters. Partial factor productivity, agronomic efficiency, partial nutrient balance, apparent recovery efficiency, internal utilization efficiency, and physiological efficiency were also taken as N use efficiency parameters for Chapter 2 only. In Chapter 2, nitrogen uptakes of rice plant samples were taken at physiological maturity stage to determine nitrogen use efficiency of rain-fed lowland rice. The overall experimental results revealed N rates; different nitrogen sources, methods and time of applications and nitrogen sources with rice varieties had a significant effect on the growth, biomass and grain yields. Similarly, N rates had also significant effect on N use efficiency of lowland rice in Chapter 2. Generally, rain-fed lowland rice grain yield (4.2-5.2 tons ha–1) positively responded to fertilizer N rates from 138 to 276 kg ha-1. In this study, mud-balls making Urea is a tedious and labor-intensive work and it is not outmaneuvered as compared to farmers' practice. Rather, hence, other labor-