Smart irrigation monitoring and control strategies for improving water use efficiency in precision agriculture: A review

The demand for freshwater resources has increased in recent times and has been exacerbated by escalating global population and increasing drought indices in the world's agricultural zones. Irrigated agriculture is inevitably a wasteful water user that has deprived other sectors of the scarce resource. Improving water use efficiency in irrigated agriculture is therefore crucial for sustainable agricultural production to thrive. There is potential to improve water use efficiency through smart irrigation systems, especially with the advent of wireless communication technologies, monitoring systems, and advanced control strategies for optimal irrigation scheduling. This paper reviews state-of-the-art smart monitoring and irrigation control strategies that have been used in recent years for irrigation scheduling. From the literature review, closed-loop irrigation control strategies are efficient than open-loop systems which do not cater for uncertainties. It is argued that combining soil-based, plant, and weather-based monitoring methods in a modelling environment with model predictive control can significantly improve water use efficiency. This review shall help researchers and farmers to choose the best irrigation monitoring and control strategy to improve irrigation scheduling in open field agricultural systems.