Vetiver root-soil complexes were utilized, and direct shear tests as well as root weight density (RMD) measurement experiments were conducted on these complexes at the different depths h and growth periods (t), ranging from 1 to 16 months. RMD, different over growth periods and depths, was analyzed for its impact on the shear strength increments. The experimental results demonstrated that the variation rules of the shear strength increments and RMD with respect to the growth periods (t) were essentially identical. With RMD at its core, a meticu...