Soil sensing technology improves application of irrigation water

Dynamic irrigation scheduling for Variable-rate irrigation systems is essential to accurately estimate the spatiotemporal pattern of irrigation water requirement. Real-time, sensor-based and soil-water balance scheduling methods were compared on a trial under a Variable-rate center pivot irrigation system. The soil-water balance scheduling used the FAO56-ET model to calculate daily soil-water deficits and to determine crop water requirements using climate data from a local climate station. The sensor-based scheduling system used a wireless soil moisture sensing network to trigger irrigation when soil water deficit reached a critical value in a web-based user interface. The scheduling was conducted on pea and French bean crop trials under one center pivot, with two delineated irrigation management zones at Massey University’s No.1 Farm, Palmerston North, New Zealand. The results showed variation between the two scheduling methods where the soil water balance assumed that the soil is well drained. The sensor-based scheduling technique delivered 27–45% less water. As there were no significant crop growth and yield differences between the two approaches, irrigation-water-use efficiency was greater under the sensor-based scheduling regime. Further research is planned to assess the feasibility of including this monitoring system in a precision irrigation control system.