Agriculture and deforestation contribute approximately one third of global greenhouse gas emissions. Major sources of emissions in this sector are from loss of soil carbon due to repeated soil disturbance under typical crop cultivation, fossil fuel use in the production of synthetic fertilisers, direct and indirect soil nitrous oxide emissions from fertiliser application, pesticide manufacture and use, and fossil fuel combustion in machinery use (e.g. tractors, irrigation, etc). Although knowledge of emissions sources aids in the determination of potential mitigation strategies (reduced or no-till methods, use of N-fixing leguminous crops in rotations, use of lower emissions fertilisers), there currently exist limited decision support and knowledge transfer tools to enable the farmer or grower to make choices appropriate to existing management practices. In this article we present a model, and open source software tool called the "Cool Farm Tool" integrating several globally determined empirical models in a greenhouse gas calculator. The software, in requiring inputs of which a farmer typically has good knowledge (and no more), has a specific farm-scale, decision-support focus. Due to its use of only readily available farm data, there is considerable scope for its use in global surveys to inform on current practices and potential for mitigation.
