In this paper, we address a motion planning problem for an autonomous agricultural vehicle modeled as tractor-trailer system. We first present a numerical approach and a primitive-based approach for computing the time-optimal path based on given static initial and goal configurations. In the former approach, we define a value function for the entire state space. The value function is consistent with the time to reach goal configuration, and it is finally used to compute the optimal trajectory. In the latter approach, based on the regular and singular primitives, we present an algorithm to construct such primitives and derive the final path. Subsequently, we extend the results and present a dynamic motion planning strategy to accommodate the case of mobile target configuration. Finally, simulation results are provided to validate the feasibility and effectiveness of these techniques.