With the linear growth in demand for food, the need for smart and optimized agriculture is emerging as a primary solution in the modern economy. It is observed that farmers have to bear enormous financial losses due to poor forecasting of weather conditions (temperature, humidity, light, etc.) as well as imprecise irrigation for large-area crops. The evolution of wireless sensor network (WSN) technology has brought automatic irrigation to life in a different way in ever-growing agricultural fields. In this article, we propose a mathematical model for an automatic irrigation system that uses WSNs to optimize the use of water quantities and also maximize crop yield using combinatorial optimization tools like AMPL.