Objectives Efficient water and gas transportation is necessary for maintaining the sustainability of soil fertility. We investigated the effects of different tillage and mulching measures on physical properties of soil in the dry farming area, to provide reference for sustainable farmland management in the Loess Plateau.

Methods This study was conducted on a long-term field trial in the Weibei dryland which started in 2002. The selected treatments included conventional tillage (CT), conventional tillage + straw mulching (TS), conventional tillage + plastic film mulching (TP), conventional tillage + whole plastic film mulching(TWP), no-tillage (NT), no-tillage + straw mulching (NS), no-tillage + plastic film mulching (NP), and no-tillage + grass mulching (NG). During the spring maize harvest in 2019, soil samples were collected for the determination of soil water content, soil bulk density, soil air permeability, relative gas diffusion rate, soil mass water content, and saturated hydraulic conductivity (SHC) in 0–10 cm, 10–20 cm, 20–30 cm, and 30–40 cm soil layers.

Results Compared with CT, TS increased average mass water content in 0–40 cm soil layer, decreased air conductivity in 0–40 cm layer, increased relative gas diffusion rate in the four soil layers, but reduced SHC in 0–10 cm layer by 75.9%. Compared with CT, TP increased soil bulk density in 0–20 cm layer, increased soil air conductivity in 0–10 cm layer by 54.1%, but reduced total soil porosity in 0–40 cm layer. Compared with CT, TWP treatment increased soil bulk density in 0–20 cm layer, increased soil air conductivity in 0–40 cm layer by 64.8%, increased SHC in 0–40 cm layer by 111.2%, but decreased total soil porosity. Compared with NT, NS increased total porosity in 0–10 cm layer, increased surface soil mass water content, relative gas diffusion rate, and saturated hydraulic conductivity by 14.8%, 25.3%, and 446.4%, respectively, but reduced soil bulk density. Compared with NT, NP decreased total porosity, decreased soil air conductivity by 33.7%, but increased surface soil mass water content and SHC by 3.5% and 145.2%, respectively. Compared with NT, NG increased total porosity, increased surface soil mass water content by 11.3%, but decreased relative gas diffusion rate (by 42.1%) and soil bulk density. Compared with CT under the same mulching conditions, NT reduced soil bulk density in 20–40 cm layer, increased total soil porosity and water holding capacity. Although NT reduced air conductivity in surface layer (0–10 cm), it increased soil relative gas diffusivity and SHC.

Conclusions No-tillage with straw mulching reduced surface soil bulk density, but increased total porosity, relative gas diffusion rate, saturated hydraulic conductivity, and air permeability in deep soil layer. The combination of traditional tillage and year-round mulching performs best in increasing soil air permeability, relative gas diffusion rate, and saturated water conductivity in surface or cultivated soil layer.