Large exchanges of carbon dioxide (CO2) occur between the atmosphere and agricultural ecosystems, but emissions are thought to be roughly balanced by uptake, giving a net flux of only around 40 Mt CO2/yr, less than 1% of global anthropogenic CO2 emissions. Many uncertainties remain, not least because emissions can vary widely, both spatially and over time, but strong relationships do exist. Direct N2O emissions from soils are related to N inputs meaning they are very low in some African countries, where crops are generally under-fertilised, but very significant in parts of Asia, where fertilisers are often applied far in excess of crop demand. As the world's largest consumer of mineral N fertilisers, China is estimated to emit roughly 0.3% of total global GHG emissions as direct N2O emissions from N inputs alone. As a result, there is significant scope for mitigating agricultural GHG emissions by improving nutrient management, through the wider use of strategies such as fertiliser Best Management Practices. Making the best use of nutrient resources allows increases in crop yields while minimising the N inputs required to achieve these and the resulting GHG emissions. Global agricultural production needs to increase to meet the demands of a rising population and increasing yields from existing cropland minimises the requirement for more land to be brought under cultivation. This is important because land use change is still an area of considerable uncertainty but may contribute as much as 17% of current total global GHG emissions.