GPS-Based Remote Sensing for Soil Moisture Measurements

Competition for limited water resources is one of the most critical issues being faced by irrigated agriculture in the United States. Site-specific irrigation applies water to match the needs of individual management zones within a field, significantly reducing water consumption, runoff, and nutrient leaching into ground water. Remote sensing for real-time and continuous soil moisture measurements at specific depths is essential for success of site-specific irrigation system.

Replicated tests were conducted to investigate the feasibility of utilizing a GPS-based sensor technology to determine soil moisture by recording the GPS signal reflected from the earth's surface. The effects of soil texture, soil compaction, and ground cover on the GPS reflectivity were determined. Our results showed that the space-based technology has a potential for determining soil volumetric moisture content in the pursuit of site-specific irrigation management. There were strong correlations between the GPS reflectivity measurements and soil moisture contents as affected by soil texture, cover crop, and soil compaction.