The aim of the paper is to present a dynamic mathematical model developed for assessing the potential greenhouse gas (GHG) emissions and economic impact associated with bio-resources from agricultural and forestry wastes. Agriculture is directly associated with climate change issues on environmental, economic and social dimensions. Agricultural activities emit greenhouse gases that, on their turn, influence the agricultural productivity. Part of the agricultural GHG emissions arises from crop production, and crop residue decomposition and burning. Conversely, forests work as removers of the GHG emissions from the atmosphere. However, the increasing wood felling generates forestry waste that gradually decomposes, thus also generating emissions. To avoid these emissions and to gain an added value the agricultural and forestry wastes can be turned into valuable resource. In this study, a mathematical model is developed that simulates the interaction between agricultural and forestry activities, generated waste and their efficient use, and the GHG emissions. Several scenarios are developed where application of the waste as resource for fuel is assessed with respect to environmental and economic aspects. We build a model where system dynamics modeling approach is used. The results show the fuel energy that can potentially be generated from agricultural and forestry residues and how net GHG emissions change depending on the selected amount of removed waste materials.