Applications of Sensing to Precision Irrigation

Abstract

Precision irrigation aims at improving productivity and sustainability by addressing spatial as well as temporal variability of soil and crop water status. This chapter presents three case studies from south-eastern USA, Israel and Spain which relate to different attributes of precision irrigation: (1) type of precision: whether it targets the spatial variability by using variable-rate irrigation (VRI) system or the temporal variability by using automatic triggering of the irrigation, (2) type of irrigation system, and (3) type of data the system uses for irrigation decisions. Each of the case studies addresses a unique combination of attributes and together they draw a more complement picture of precision irrigation. All case studies have shown that well-timed data provides decision support for VRI management, i.e. soil moisture sensor-data (south-eastern USA and Spain) and thermal aerial imagery (Israel). The three case studies showed that precision irrigation treatments performed better than uniform irrigation. Yield increased by 4.3–12% and water-use efficiency (WUE) was improved by 14–40%. The reliance on point-sensor data in the case studies from south-eastern USA and Spain dictated the use of pre-determined irrigation management zones (IMZ), yet, enabled adaptive in season irrigation management. In season remotely sensed images can be further used for adaptive IMZ, i.e. to modify their boundaries, yet it currently suits VRI in drip irrigation. From these case studies, it can be seen that full VRI implementation, which adapts for spatial and temporal changes, faces “site-specific” challenges, i.e. every irrigation system is unique, and thus requires tailored solutions.