The objectives of this paper are to present a material balance model relating to the national and regional (Yangpyeong County) levels, and to discuss the problem of using it for assessing environmental pressure from agricultural production activities. The result shows that the amount of macro-nutrients (i.e., nitrogen, phosphorus, and potassium) based on ingredients are over-supplied 184.4 percent at the national level and 136.5 percent at Yangpyong county. Based on the evaluation of the results of this study, several suggestions are offered for managing materials balance. To minimize the over-supply or losses of plant nutrients from the agricultural ecosystem, the input of nutrients to the system needs to be reduced. This can be achieved by increasing the level of recycling within the system. The important policy measures are to establish best management practices (BMP) for reducing agro-chemicals and to promote the natural cycling system through the interaction between crop and livestock sectors. Further development of the approach is required through including dynamic aspect of nutrient application and socio-economic aspect, extrapolation of results to other regions, better estimation of nutrients flows and adding policy oriented activities.