高羊茅根土复合体阻抗红壤、高岭土、河沙水力分离的机制试验

[Objective]In order to reveal the complex relationship between root and soil substances,i.e.The dual action mechanism of plant root system on the one hand improving the cohesion of soil particles while impeding or delaying the separation of soil particles due to hydraulic erosion;[Method]Festuca arundinacea,a representative plant widely used in water and soil conservation,was selected as the experimental material,The root-soil complex was formed by sowing in a shear ring box with red soil,kaolin and river sand as growth substrates,including particle composition,scanning of root structure,determination of organic matter carbon,hydraulic scouring experiment of the complex and shear strength experiment of the complex.[Result]The results showed that: (1).Root length density,root surface area density and root volume density in root factors are significantly positively correlated with each other,and are significantly positively correlated with the growth of organic matter in the complex;Root factors and distribution are significantly affected by soil types,with the best performance in river sand. (2).Compared with the blank without grass,the cohesion and impact resistance of tall fescue to red soil,kaolin and river sand root soil complexes are significantly improved.The cohesion of river sand of root-soil composite increased from 0.034 to 1.72kpa,and the scour resistance index increased from 1.26 to 2.7(117%).The cohesion of red soil root-soil complex increased from 4.31 to 6.78kpa(increased by 57%),and the impact resistance increased from 1.18 to 6.47(increased by 449%).The cohesion of kaolin root-soil composite was increased from 3.11 to 5.39kpa,and the impact resistance was increased from 0.92 to 4.55(395%).The order of scour resistance of the three soils is red soil>kaolin>sandy soil. (3).There are significant differences in the soil anti-scour properties in different depths.The soil anti-scour properties in 0-2 cm depth are much greater than those in other soil layers.The order of anti-scour properties is:surface layer>sub-bottom layer>sub-surface layer>bottom layer. (4).After the expression of anti-scour index and scour modulus converted into scour time per gram of soil and scour water consumption per gram of soil,it was found that the root surface area density of root-soil complex was significantly negatively correlated with the energy consumption per gram of soil scoured in the first minute,positively correlated with the time consumption per gram of soil scoured in the second minute,and significantly negatively correlated with the energy consumption per gram of soil scoured in the second minute.The similarity relationship in the second minute also includes root length density and root surface area density,which are positively correlated with the time consumption of scouring per gram of soil in the second minute and significantly negatively correlated with energy consumption.As a result,that formation of the root-soil complex increase the time and energy consumption of the separation of sandy soil,red soil and kaolin,The denudation time of thin-layer water flow was delayed by 0.101-0.208 seconds in the first minute and 0.36-0.488 seconds in the second minute,increasing the energy consumption by 0.186-0.311 units of water energy in the first minute and 0.28-0.429 units of water energy in the second minute.[meaning]The research results provide new scientific reference basis for the research on the reduction of soil separation by root soil fixation mechanism.