Abstract:In the mechanical replugging task in greenhouse, the residual matrix in plastic pan would not be beneficial for healthy seedling replugging which was caused by the endeffector removing bad seeding in previous transplanting procedure. A kind of spade endeffector was developed relatively to the needletype for the removing task. The aim was to reduce the residual matrix in the cell by increasing the contact area between the endeffector and matrix. The reasons of residual matrix in the endeffector grabbing procedure were deduced by the statics. The seedling pot would break and the matrix would collapse while the maximum cohesion in matrix was less than the total resistance which was synthesized by the gravity of seedling pot and the adhesion between the matrix and plug tray. Based on the discrete element analysis method, the seedling pot grabbing procedure by the spade endeffector was simulated by the enhanced discrete element method (EDEM). It was found that the performance of residual matrix was reduced while the cohesion of soil matrix was increased. Therefore, taking the matrix ratio and relative moisture content as the main factors and designing the experiment through the combined disc tests to measure the matrix adhesion and cohesion in the different main factors of matrix ratio and relative moisture. The aim was to find the conditions of matrix ratio and relative moisture while the cohesion was bigger than adhesion. The difference between cohesion and adhesion was the largest under the conditions of 60% of relative moisture content and 6∶3∶1 (peat∶vermiculite∶perlite) of matrix ratio. The average matrix removal rate by the spade endeffector reached 70.8%, which was superior to other conditions. Most of the matrix in the plastic hole can be removed under the conditions.