Abstract
The letter aims to generalize the second KP equation to a new one which still possesses a trilinear form. We construct Wronskian determinant solutions, based on its associated trilinear equation, instead of a Hirota bilinear form. Multi-soliton solutions are generated from the presented Wronskian formulation with higher-order dispersion relations. It is then shown that the extended second KP equation possesses resonant N-wave solutions. Moreover, generic one-lump and two-lump waves are built via the improved long wave limit procedure.