旱作区典型土类穿透阻力分布特征及耕层厚度确定

为探明不同土类的穿透阻力变化特征与影响因素,针对中国黄淮海旱作区与东北旱作区的潮土、褐土、黑土、黑钙土、砂姜黑土与棕壤共6种典型土壤,测定了0—40 cm穿透阻力,分析其垂直分布特征,建模分析了0-20 cm内穿透阻力与土壤理化性质(含水量、容重、质地、有机质含量)的量化关系,基于趋势分析,确定了不同土类的耕层厚度。结果表明:(1)在0—40 cm土层内,穿透阻力有着随土层深度的增加先增加后稳定的特征。平均穿透阻力最小的土类和亚类分别为黑钙土1.188 MPa和普通暗潮土0.819 MPa,最大的为褐土1.706 MPa和壤质石灰性潮土1.829 MPa。(2)在0—20 cm范围内,针对不同土类,不同建模方法的建模效果不同,偏最小二乘回归适用于潮土、黑土、棕壤,对褐土、砂姜黑土使用多元线性回归效果较好,随机森林回归则适用于黑钙土。开发的经验公式有助于阐明穿透阻力的变化因素。(3)Mann-Kendall法和Pettitt法可以客观地确定并检验耕层厚度,旱作区典型土类耕层厚度从大到小依次为褐土22.5 cm,潮土21.5 cm,棕壤20.0 cm,黑钙土16.0 cm,砂姜黑土15.0 cm,黑土14.0 cm,褐土、潮土、棕壤区可适当深耕,种植根系发达的作物,黑钙土、砂礓黑土、黑土区需要多加保护,减少大规模农机的使用。

Distribution Characteristic of Penetration Resistance and Determination of Plough Layer Thickness of Typical Soils in Dry Farming Area

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.