The decline of soil fertility has been one of the major constraints to low level of agricultural productivity and it primarily referred to the exploitation of soil nitrogen. Nitrogen could be added to or lost from the soil via different natural and human-induced processes. The work area is located in lower bilate river basin within the ethiopian rift valley which was characterized by an arid climatic conditions. The core objectives of this work were modeling of the soil nitrogen balance and the plant available stock soil nitrogen by using GIS and Remote sensing and assessing the uncertainities and source of errors. The widely used methodology of Stoorvogel and Smaling was adapted for soil nutrient balance estimation while the plant available stock soil nitrogen was determined using empirical relations. This book described acomprehensive methodology which is spatially explicit for modelling soil nitrogen balance and is very useful to professionals working in agricultural land management and especially to those who developed models for soil nitrogen