Testing DRIP-GPS: a simulation study on real-time precision irrigation with GNSS-R

Irrigation is a core component of crop production, and variable rate irrigation (VRI) can conserve up to 15% water, improve soil health, and boost yield. Current pivot-based dynamic VRI systems utilize a network of infield soil moisture (SM) sensors to create irrigation prescription maps, which allow differential water application across the field in different irrigation management zones (IMZs). These maps are generated every one to two days, making the SM prescription map static in temporal resolution, and the in-situ SM sensors offering only point data could limit the spatial resolution. Depending on the map generation time and irrigation period, these limitations could lead to areas being over-watered or under-watered across the field. On the other hand, Global Navigation Satellite System (GNSS) Reflectometry (GNSS-R) has shown great promise in measuring SM using remote sensing. They use reflected L-band GNSS signals that vary, depending on the moisture level in the top 5 cm of soil. However, the spatial resolution of spaceborne GNSS-R observations is very coarse (in the range of kilometers), limiting their application in precision agriculture (PA). To enable an efficient, high-spatiotemporal resolution dynamic VRI system, we present a simulator to evaluate the feasibility of using Dynamic Real-time Irrigation Planning using GNSS-R Pivot System (DRIP-GPS). The DRIP-GPS system deploys GNSS-R receivers on the pivot arms to estimate instantaneous surface SM measurements. We simulate the GNSS-R sensors on pivot arms for real-time surface SM estimation, calculating sensor positions, orientations, and the number of sensors needed for optimal coverage. The simulator evaluates the system’s spatial and temporal resolution, factoring in pivot speed, orientation, and satellite positions to assess its potential for high-precision irrigation in real-world conditions. Preliminary results from a field deployment are also presented, showing promising results.

Read the paper at: Testing DRIP-GPS: a simulation study on real-time precision irrigation with GNSS-R.