Soil Salinity of an Urban Park after Long‐Term Irrigation with Saline Ground Water

Abstract

Core Ideas Changes in soil salinity after 46 yr of irrigation. Using electromagnetic induction to map soil salinity and sodicity. Correlate soil salinity with irrigation system distribution uniformity. Chamizal National Park, located in El Paso, TX, extends over 140,000 m2 and has been irrigated with saline water for 46 yr. In recent years, turf areas in the park have severely degraded and bare spots have developed. Root zone salinity and sodicity were suspected to be the main reasons for the turf conditions. Developing salinity management and remediation strategies to improve turf quality requires information on the distribution of salinity (ECe) within the turf root zone. Electromagnetic induction (EMI) uses apparent electrical conductivity (ECa) to delineate salinity distribution, and is reportedly superior to traditional wet chemistry analyses. This study was conducted to investigate the spatial distribution of soil salinity and sodicity using the EMI technique. In addition, we assessed irrigation distribution uniformity and compared findings with root zone salinity and sodicity. The EMI data correlated well with saturated paste results and indicated that root zone salinity ranged from <1 to 43 dS m−1. In several parts of the park, ECe exceeded the threshold values for bermudagrass of 15 dS m−1. Root zone sodium adsorption ratio values ranged from <1 to 21 mmol1/2 L−1/2 and in areas where increased runoff and surface ponding were observed, values exceeded the threshold level of 12 mmol1/2 L−1/2. Correlation analysis between irrigation uniformity parameters and standard deviation of ECe and SAR values revealed that more than 90% of the variability of EC and SAR in the top 30 cm of the root zone could be explained by irrigation uniformity.