From Sensors to Solutions: Understanding Coastal Salinity

• Ella Williams, Biological Sciences, Salisbury University

• Jarrod Miller, Plant and Soil Science, University of Delaware

Coastal farmland is being inundated with saline waters, including high levels of sodium (Na⁺). Farmers and landowners need methods to manage and mitigate saline soils. However, we need to effectively map where field salinity exists. This project used a Veris electrical conductivity (EC) mapper across a field undergoing saltwater intrusion. Twelve soil samples were obtained based on the Veris map and sodium concentrations were regressed against EC. Drone based normalized difference vegetation index (NDVI) was mapped during the growing season. Average EC Na⁺, elevation (m) and NDVI were extracted in Arc GIS using a fishnet. A segmented regression determined elevation breakpoints for Na⁺ and NDVI. Sodium starts increasing in concentration below 1.25m above sea level while corn NDVI starts decreasing below 0.88m above sea level. From prior research corn growth was expected to decrease around 0.79m (340ppm Na⁺). Corn survival is minimal where avg. Na⁺ was ~484 ppm. Gypsum can be recommended for a smaller footprint in the field and EC_a maps can successfully produce variable rate prescriptions, field evaluation is necessary.