How to increase maize production without extra nitrogen input

•Increasing crop yields while reducing environmental impacts are a great challenge to ensuring food security and environmental quality.•Increasing plant density appropriately is one of the most effective strategies for increasing maize yield worldwide.•Overuse of nitrogen (N) fertilization on maize is popular and has resulted in excessive N surplus in the soil in China.•Maize yield were increased by 5.59% through increasing plant density without extra N inputs and meanwhile reactive N losses intensity and GHG intensity decreased by 2.2% to 10.2% across China.