Abstract:In order to explore the variation characteristics and influencing factors of penetration resistance of different soil types, taking six typical soils in Huang Huai Hai dry farming area and northeast dry farming area, including fluvo-aquic soil, cinnamon soil, black soil, chernozem soil, lime concretion black soils and brown soil, as research objects, 0-40 cm penetration resistance was measured, and its vertical distribution characteristics was analyzed. The quantitative relationship between penetration resistance and soil physical and chemical properties (water content, bulk density, texture and organic matter content) within 0-20 cm soil layer was analyzed. The thickness of the plough layer of different soil types was determined based on trend analysis. The results showed that:(1) In the 0-40 cm soil layer, the penetration resistance increased first and then kept stable with the increasing of soil depth. The lowest average penetration resistance was 1.188 MPa for chernozem and 0.819 MPa for ordinary dark aquic soil, respectively, while the highest was 1.706 MPa for cinnamon soil and 1.829 MPa for loamy calcareous alluvial soil, respectively. (2) In the range of 0-20 cm, for different soil types, different modeling methods had different effects. Partial least squares regression was suitable for fluvo-aquic soil, black soil and brown soil, and multivariate linearity was better for cinnamon soil and sand ginger black soil. The random forest regression was suitable for chernozem. The empirical formula developed in this study helps to clarify the changing factors of penetration resistance. (3) Mann-Kendall method and Pettitt method could objectively determine and examine the thickness of the plough layer. The plough layer thickness of typical soils in dry farming areas was 22.5 cm for cinnamon soil, 21.5 cm for fluvo-aquic soil, 20.0 cm for brown soil, 16.0 cm for black Calcium soil, 15.0 cm for sand ginger black soil and 14.0 cm for black soil. In cinnamon soil, fluvo-aquic soil and brown soil area, deep ploughing was suitable, and crops with developed root systems could be cultivated. Chernozem soil, sandy black soil and black soil area needed more protection, and the application of large-scale agricultural machinery should be reduced.