COSMIC-SWAMP: IoT enabled cosmic ray sensors for irrigation monitoring

Abstract

Approximately 70% of fresh water usage worldwide is for irrigation purposes, therefore the adoption of novel irrigation approaches such as IoT enabled precision irrigation has the potential to improve resource efficiency within the agricultural sector, and build resilience to climate change related water shocks at a global level. One difficulty in adopting smart irrigation farming practices comes from a lack of efficient methods to continuously monitor soil moisture within the root zone with high precision. Up until the last decade, measurements have typically relied on traditional invasive point scale sensors, or satellite data for continuous monitoring. The challenge with both of these monitoring methods is that they do not provide an optimal solution for the measurement scales required for irrigation farming, with many point probes required to accurately account for soil heterogeneity over even a modest size site, and satellite data being too coarse a resolution for data-driven precision irrigation to be a viable option. Cosmic Ray Neutron Sensing (CRNS) has been adopted in the environmental and hydrological sensing community in the past ten years as an alternative way to non-invasively measure soil moisture. Since a single neutron detector can have a sensitive footprint up to 200 m away, the technique can provide a volumetric water content estimate at a length scale that is better suited for monitoring of typical agricultural fields, and fills the gap between point probes and satellite data. One major challenge faced by the CRNS technique is that the Helium-3 detector systems used to date can be costly, limiting its usefulness in cost limited applications. To avoid this, several groups have begun developing low cost alternatives to Helium-3 based systems, and the field is reaching a critical point in which the technique could become a viable solution for precision irrigation agriculture. This proposal aims to bring together leaders in the development and utilisation of soil moisture sensors for agriculture to understand how a powerful hydrological monitoring technique, cosmic ray neutron sensing, could be adapted to best suit irrigation monitoring. By modifying two newly developed low cost cosmic ray neutron sensors so that they can interface directly with an Internet-of-Things Smart Water Management Platform (SWAMP) network, it will be possible to correlate cosmic ray neutron data with a variety of other data streams in almost real time to support data driven precision irrigation modelling within agriculture in a standardised way. Testing these systems at a pivot irrigation site in Brazil made available to the researchers through the international network, will provide the first demonstration of this interface on a full scale SWAMP network, and will place the research network in a strong position to apply the sensors to range of other precision irrigation applications in the future. (AU)