Comparison Of Root Mechanical Properties Of Two Soil And Water Conservation Plants In Arid Area

In this paper,the root system of Hippophae rhamnoides and Hedysarum monggolicum turez,two typical wind and sand fixation plants for soil and water conservation in arid and semi-arid areas,was used as the research object to carry out the experimental study on the axial ultimate tensile resistance of single root,the shear resistance of root soil composite and the friction resistance of root soil interface in the laboratory;hp-500 was used in the field natural environment Digital push-pull meter and self-made portable test instrument were used to study the tensile resistance of callus self-healing of two kinds of plant roots after tensile damage,and then revealed the differences of mechanical properties between the two kinds of plant roots materials,which provided basic mechanical data for the study of plant species selection and resource allocation in soil and water conservation and ecological restoration in this area.The results show that.(1)In the range of 0-5mm,the ultimate tensile strength of single root increased as a power function with the increase of diameter,while the ultimate tensile strength of single root decreased as a power function with the increase of diameter.The ultimate tensile strength of single Sea buckthorn was(26.49±22.5A)MPa>that of yangchai(19.58±15.41B)MPa.(2)The shear strength and cohesion of the two plant root soil complexes are higher than that of the plain soil.Under the condition of 12.5 kPa(80 cm soil layer),the shear strength and cohesion of the two plant root soil composite generally increased first and then decreased with the increase of root diameter and root density.Under the representative root diameter class,the order of shear strength is Seabuckthorn(22.15±2.1 A)kPa>yangchai(16.37 ±4.01 B)kPa>plain soil(3.8±0.24C)kPa.The cohesion of sea buckthorn was(7.19±2.33A)kPa>that of yangchai(5.99 ±2.14B)kPa.The shear strength of two plant root soil composite under fast shear is greater than that under slow shear.There was a significant difference in the shear strength of the two plants under the fast shear(0.8mm/min),the value was Sea buckthorn(18.95±0.75A)kPa>firewood(18±0.83B)kPa,and the shear strength under the slow shear(0.02mm/min)was Sea buckthorn(15.48 ±0.44B)kPa>yangchai(14.3 ± 0.77C)kPa.(3)The resistance tension of single root increases with the increase of diameter.There were significant differences in the resistance of sea buckthorn and firewood under the representative root diameter class.The resistance of sea buckthorn under the representative root diameter class was 1-1.5mm(32.52 ± 0.91 a)N>0.5-1mm(27.48 ± 0.74 b)N,and that of firewood was 1-1.5mm(18.39 ± 0.41 a)N>0.5-1(14.44 ± 0.36 b)N>0-0.5mm(10.56 ± 0.89 c)N.The mean value of the shear strength decreased with the increase of the root diameter as a power function.The shear strength values of the root soil interface of the two plants are greater than that of the soil soil interface.At the significant level of 0.05,the difference between the two plant root soil interface and the soil soil interface is significant,and both of them are greater than the shear strength value of the soil soil interface.The order of magnitude is:Sea buckthorn root soil interface(16.78±1.04 A)kPa,poplar root soil interface(15.45 ± 1.18 A)kPa>soil soil interface(8.97 ± 0.35 B)kPa.(4)In the range of 0-4mm test diameter,the ultimate tensile strength of two kinds of plant roots after 3 months of tensile damage was less than that of the parallel control(no tensile damage disturbance).At the significant level of 0.05,compared with parallel control(16.73±9.73 a)n,25%(16.59 ± 5.19 b)n>55%(10.58 ± 7.28 c)n>75%(3.63±1.68 d)n;compared with parallel control(16.16 ± 9.32 a)n>25%(12.65 ±7.6 b)>55%(0.84±7.95 c)>75%(.48±3.34 d)?The greater the damage,the smaller the ultimate tensile strength.When the root diameter is 0?4mm,the root ultimate strain decreases with the increase of root diameter.The difference was 3.7%in 3-month callu and 5.7%in 5-month callus,which was the opposite to that of yangchai.The elastic modulus of straight root decreased with the increase of diameter in the range of 0-4mm.The results showed that the root mechanical properties of two plants were better than that of H.Rhamnoides.