Non-collocated sliding mode control of partial differential equations for soil irrigation

•Sliding mode control (SMC) is developed to regulate the water content in the soil.•The movement of water in the soil is modeled by the Richards partial differential equation (PDE).•The proposed SMC can be also applied to other parabolic PDEs, such as the diffusion and heat equations.•The non-collocated sensor and actuator SMC of PDEs is considered.•Non-standard sliding manifolds are proposed.