Test method for reducing test error in shear strength of root-soil composite

A test method for reducing test error in shear strength of a root-soil composite, comprising the following steps:

• Step 1:
• determining an actual shear surface where a shear process occurs between a tillage component and soil during a tillage process, measuring a dihedral angle between the actual shear surface and a soil horizontal plane when a tillage depth is reached, and measuring an actual shear depth H imparted to the soil by the tillage component during the tillage process;
• Step 2:
• planning sampling along the actual shear surface from a horizontal ground surface to a tillage depth range by stratifying according to a diameter of a ring knife, based on the actual shear depth H generated in the soil during the shear process of the actual tillage, and obtaining stratified measurement depths;
• Step 3:
• planning one annular sampling area in each layer based on the planned stratified measurement depths;
• Step 4:
• preparing a sampling plane according to the dihedral angle α of the actual shear surface within a same depth range, placing the ring knife perpendicular to the sampling plane, and performing sampling in various directions along the planned annular area;
• Step 5:
• respectively acquiring root-soil composite samples within the annular area taken in each layer, and performing a root direct shear test in a stratified manner to obtain test results;
• and
• Step 6:
• expressing a shear strength of the soil in each layer in a stratified manner based on the test results.