Nitrous oxide (N 2 O) is a potent greenhouse gas, and its mitigation is a pressing task in the coming decade. However, it remains unclear which specific process between concurrent nitrification and denitrification dominates worldwide N 2 O emission. We snagged an opportunity to ascertain whence the N 2 O came and which were the controlling factors on the basis of 1315 soil N 2 O observations from 74 peer‐reviewed articles. The...