Smart fuzzy irrigation system for litchi orchards

Sustainability of orchard crop production can be improved by developing more efficient irrigation control sys-tems. Soil moisture deficiency can lead to yield reduction; however, excess soil moisture can reduce the diffusion of oxygen to the root system, which can result in hypoxia that causes harmful results. The particle swarm optimization (PSO) algorithm can fall into the local optimal solution, and therefore, it requires further optimi-zation. In addition, a mathematical model that can effectively describe the system is difficult to obtain in complex systems with nonlinear characteristics, such as in irrigation systems. Therefore, a smart irrigation fuzzy control system based on an improved PSO algorithm is proposed in this study. Simulation and field experiments were conducted to analyze the effectiveness of the system. The simulation results showed that the proposed irrigation control algorithm achieved better transient performance and control precision. Further, the time required to enter the steady state and the overshoot were reduced by 40% and 76%, respectively, compared to the values for general fuzzy control. The experimental results showed that the irrigation system proposed in this paper can increase the average soil moisture of litchi orchards to 16.43% with an average deviation of 0.00826. The general fuzzy irrigation system achieved an average soil moisture of 16.83% with an average deviation of 0.01107, which implies the proposed irrigation system's good control performance. The results indicate that the system is more efficient for making the soil moisture suitable for litchi growth. This research was meaningful with regards to controlling the soil moisture stably and thereby providing a valuable reference for the litchi orchard's irrigation.