Agricultural research in East and Southeast Asia is increasingly challenged by the search for land-use options that best match multiple development objectives of rural societies (e.g., increased income, food security, and reduced environmental pollution). In order to support the identification of sustainable land-use options and to support decision making with respect to land use, a tool was developed for quantifying inputs and outputs of cropping systems at the field level. TechnoGIN, the tool described in this paper, integrates systems analytical and expert knowledge and different types of agronomic data enabling the assessment of inputs and outputs of a broad range of cropping systems and the evaluation of their resource use efficiencies. By using methods of spatial aggregation in combination with linear programming, results can also be used to explore trade-offs in resource-use efficiencies at higher levels such as the farm household, municipality and province. New features in TechnoGIN compared with similar tools include the annual rotation of up to three crops, the distinction between aerobic and anaerobic growing conditions of crops, and the procedure for estimating crop nutrient uptake. TechnoGIN is illustrated with results from the Tam Duong district in North Vietnam. The design of TechnoGIN enables easy access to its data, parameters and assumptions, and rapid generation and evaluation of input–output relationships of cropping systems in order to add new information and to improve data. TechnoGIN raises awareness about the assumptions incorporated and thus supports data collection and setting of the research agenda with respect to agro-ecological processes for which knowledge is incomplete, and is relevant for showing trade-offs between production, economic and environmental impacts of different land-use systems.