Hydraulic separation of the root-soil complex in Festuca arundinacea

To reveal the complex relationship between roots and soil materials, it is necessary to clarify the dual mechanism of plant roots that increase the soil shear strength, or delay the separation of soil particles because of water erosion. Festuca arundinacea, which is widely used in soil and water conservation, was selected as a representative plant, and it was sown in three growth substrates: red soil, kaolin, and river sand. Through physical and chemical determination of the root-soil complex, hydraulic scour and shear strength tests showed that: 1) Root length density, surface area density, and volume density in root system factors were positively correlated with each other in an extremely significant manner, and significantly positively correlated with the growth of organic matter in the complex. 2) The erosion resistance of soil at different depths was extremely different. The erosion resistance of the 0 – 2 cm soil layer was far greater than that of other soil layers. The order of erosion resistance was: surface layer > sub-bottom layer > subsurface layer > bottom layer. 3) The cohesion of the root-soil complex with 60 seeds per 30 cm ² was higher than that with 30 seeds, and its soil anti-scouring index was also the strongest. 4) The formation of the root-soil complex improved the time-consuming process of soil separation and the amount of scouring water or energy consumption. Within the second minute of action of the thin water flow, the length and time of denudation were prolonged (significantly positive correlation), and the amount of washed water or energy consumption was increased (significantly negative correlation or extremely significant). The results of this study provide a new scientific reference for the study of root consolidation mechanisms to reduce soil separation.