The growing demand for biofuels has led to an increased demand for feedstocks which in turn is anticipated to induce changes in the cropping systems or land requirement for agriculture use. This study used consequential life cycle assessment (LCA) to evaluate the environmental consequences of possible (future) changes in agricultural production systems and determine their effects on land use change (LUC) and greenhouse gas (GHG) implications when cassava demand in Thailand increases. Six different cropping systems to increase cassava production including converting unoccupied land to cropland, yield improvement, displacement of area currently under sugarcane cultivation and the other potential changes in cropping systems in Viet Nam and Australia are modeled and assessed. The comparative results show that LUC is an important factor in overall GHG emissions of the first generation biofuels especially change in soil carbon stock contributing about 58-60% of the net GHG emissions. Increased cassava production by expanding cultivation area has a significantly larger effect on GHG emissions than increased productivity. The analysis shows that increasing productivity of both sugarcane and cassava are important ways to maximize benefits in using of certain area of Thailand to serve both the food and fuel industries. (C) 2009 Elsevier Ltd. All rights reserved.