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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (5): 94-105.DOI: 10.11686/cyxb2022228

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Spatial differences in, and factors influencing, the shear strength of typical herb root-soil complexes in the Loess Plateau of China

Yu-ying CAO(), Xue-meng SU, Zheng-chao ZHOU(), Qun-wei ZHENG, Jia-hui YUE   

  1. School of Geography and Tourism,Shaanxi Normal University,Xi’an 710119,China
  • Received:2022-05-24 Revised:2022-07-08 Online:2023-05-20 Published:2023-03-20
  • Contact: Zheng-chao ZHOU

Abstract:

The aim of this study was to explore the spatial differences in the shear resistance of root-soil complexes of herbaceous plants on the Loess Plateau of China. Soils with three different textures were selected from three sites: From north to south, Liudaogou (sandy loam in Shenmu), Fangta (silty loam in Ansai), Yongshouliang (clay loam in Yongshouliang). Lolium perenne (with a fibrous root system) and Medicago sativa (with a tap root system) were planted in pots containing these soils. The soils without plants served as controls. After 4 months, the soil physicochemical properties, root characteristics, and shear strength (cohesion and internal friction angle) of root-soil complexes in the 0-10 cm, 10-20 cm, and 20-30 cm layers were measured. It was found that: 1) Soil organic matter (SOM), mean weight diameter (MWD), and cohesion (c) increased after planting L. perenne and M. sativa as compared to soils without plants, but the internal friction angle (φ) was basically unchanged. The influence of plants on the soil physiochemical and shear strength decreased with depth within the soil profile, and L. perenne had stronger effects than M. sativa on the soils’ physical and physicochemical properties and shear strength. 2) From sandy loam, to silty loam, to clay loam soils, c showed an increasing trend, andthe values of root parameters and bulk density (BD) decreased. The soils were ranked, from highest to lowest SOM and MWD, as follows: clay loam>sandy loam>silty loam. The highest values ofSOM, MWD, and c were in the clay loam soil. 3) A principal component analysis showed that root characteristics contributed significantly to the shear strength of root-soil complexes in sandy loam soil, while the soil characteristics contributed significantly to the shear strength of the root-soil complexes in silty loam and clay loam soils. This multivariate evaluation of the shear strength of root-soil complexes of herbaceous plants provides basic data and a theoretical reference for further studies of soil and water conservation on the Loess Plateau of China.

Key words: shear strength, soil texture, principal component analysis, Loess Plateau