Mobile Device for Spatial Mapping of Soil Salinity On a Golf Course.

Sites irrigated with saline irrigation water exhibit considerable spatial and temporal variability in soil salinity in response to site-specific differences in irrigation/rainfall applications, surface and subsurface water movement, and evapotranspiration [ET] patterns. Rapid, detailed mapping of soil salinity patterns on large, complex turfgrass sites would allow: a) for site-specific leaching rather than using an estimated leaching requirement over a whole area  which would aid in water conservation; b) identification of the most saline sites to be identified so that hand salinity monitoring devices could be used to monitor leaching effectiveness over time; and c) identify the best areas for installation of in-situ soil salinity sensors for real-time and multi-depth data. Data collection was performed via the Toro Mobile Multi-Sensor (TMM; patent pending) prototype data acquisition unit capable of determining in the surface 10 cm of soil GPS labeled volumetric water content (VWC) by time-domain reflectrometry, apparent soil salinity (ECa) by a capacitance/frequency domain sensor, and penetration resistance, while mapping normalized vegetative difference index (NDVI) by spectral reflectance. The mapping grid was approximately 2.5 x 2.5 meter. Joint mapping was conducted with an experimental mobile monitoring device based on measuring soil resistivity by a 4-wenner array was used to determine soil salinity on a 1.6 by 3.2 m grid on a golf course fairway (Old Collier Golf Club, Naples, FL) in August 2009 and March 2010. Geostatistical analysis of the spatial and temporal salinity patterns will be discussed comparing both devices.