N2O emissions and yield in maize field fertilized with polymer-coated urea under subsoiling or rotary tillage

Fertilizer application and tillage practices play an important role in agricultural production, whereas excess N input could create considerable N₂O emissions. However, it is unclear whether urea types under subsoiling or rotary tillage have effects on yield and N₂O emissions in maize field. We investigated the effects on N₂O emissions and maize (Zea mays L.) yield of tillage (rotary tillage [R] alone and rotary tillage following subsoiling [S]) and two types of urea (polymer-coated urea [P] and conventional urea [C]) applications, respectively, at the sowing [0] and V6 [6] stages in a clay loam soil. N₂O emissions varied from 1 to 11 kg N₂O-N ha⁻¹. Compared with S soil, the R soils produced greater N₂O emissions. Compared with conventional urea, polymer-coated urea increased maize production and fertilizer-induced N₂O emission, but had no significant effect on yield scaled N₂O emission. The increase of N₂O emission was mainly related to water-filled pore space affected by tillage and soil nitrate and ammonium N concentrations affected by urea types. Polymer-coated urea topdressing at the V6 stage in S soils was better for producing a higher yield with lower N₂O emission. The results indicate that R soils had more significant N₂O emission than S soils during a wet climate; and polymer-coated urea can increase grain yield with a slight higher N₂O emissions, whereas changing the application stage can decrease the cumulative N₂O emissions without reducing the yield.