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Croplands are the single largest anthropogenic source of nitrous oxide (N2O) globally,yet their estimates remain difficult to verify when using Tier 1 and 3 methods of the Intergovemmental Panel on Climate Change (IPCC).Here,we re-evaluate global cropland-N2O emissions in 1961-2014,using N-rate-dependent emission factors (EFs) upscaled from 1206 field observations in 180 global distributed sites and high-resolution N inputs disaggregated from sub-national surveys covering 15593 administrative units.Our results confirm IPCC Tier 1 default EFs for upland crops in 1990-2014,but give a ～ 15％ lower EF in 1961-1989 and a 67％ larger EF for paddy rice over the full period.Associated emissions (0.82 ±-0.34 Tg N yr-1) are probably one-quarter lower than IPCC Tier 1 global inventories but close to Tier 3 estimates.The use of survey-based gridded N-input data contributes 58％ of this emission reduction,the rest being explained by the use of observation-based non-linear EFs.We conclude that upscaling N2O emissions from site-level observations to global croplands provides a new benchmark for constraining IPCC Tier 1 and 3 methods.The detailed spatial distribution of emission data is expected to inform advancement towards more realistic and effective mitigation pathways.