狗牙根和三叶草的根系特征及对荒坡紫色土抗剪性能的影响

Root characteristics of Cynodon dactylis and Trifolium repens and their effect on shear performance of purple soilin barren hillside

为探讨草类根系对荒坡紫色土的固土性能及其影响因素,以该环境的紫色土为研究对象,设置了空白对照、盆栽狗牙根(Cynodon dactylon)和盆栽三叶草(Trifolium repens)3个处理,8个月后分别取样用常规方法测定土壤基本理化性质、Win RHIZO(Pro.2004c)根系分析系统测定根系指标、ZJ型应变控制式直剪仪测定根-土复合体抗剪强度。结果表明,狗牙根的根系指标优于三叶草,且在根系直径(d)≤0.2 mm径级范围内更为突出;较之三叶草,狗牙根更能有效改善土壤的理化性质;两种草类均能有效提高根-土复合体的抗剪性能。较之空白对照,狗牙根的内摩擦角(φ)和粘聚力(c)分别增加了10.37%和66.36%,三叶草的分别增加了1.14%和34.22%,其中狗牙根处理的土壤抗剪性能最优;影响根-土复合体抗剪性能的关键性指标有土壤容重、总孔隙度、毛管孔隙度和根长密度,根系直径≤0.2 mm是影响根-土复合体抗剪性能的关键性径级。

To investigate the soil reinforcement of grass roots on purple soil on barren hillsides and the factors affecting it,purple soil under the environment was assessed via an experiment with three treatments: A blank control and soil under Cynodon dactylon and Trifolium repens. After eight months,basic physical and chemical properties,root parameters,and soil shear strength were measured by conventional methods,the root analysis system( Win RHIZO( Pro. 2004 c))and strain controlled direct shear apparatus. The root parameters of C. dactylon were better than those of T. repens; root diameter of C. dactylon was significantly higher than that of T. repens( d≤0. 2 mm; P < 0. 05). C. dactylon was more effective than T. repens in improving soil physical and chemical properties. Both kinds of grass effectively improved the shear performance of the root-soil system. Compared with the blank control,the internal friction angle( φ) and cohesion( c) of soil under C. dactylon and T. repens were higher by 10. 37%,66. 36%,and 1. 14%,34. 22%,respectively,and the shear performance of soil under C. dactylon was better than that of soil under T. repens. Soil bulk density,total porosity,capillary porosity,and root length density( RLD) were the key indexes affecting the shear performance of the root-soil system,and d ≤ 0. 2 mm was the critical diameter class affecting shear performance.