The application describes a method for inserting an improvement product into a ground surface. The method comprises making a cut in the ground surface with a cutting member in a travel direction； pushing material at one side of the cutting member away from the cutting member in a direction substantially perpendicular to the travel direction with a pushing member to form a space in the ground surface located between the cutting member and the pushing member； and, inserting the improvement product in the ground surface through the space located between the cutting member and the pushing member. The cutting member vibrates in a plane comprising a line parallel to the travel direction to improve the cutting characteristics of a disk shaped cutting member.
