Electromagnetic sensing and infiltration measurements to evaluate turfgrass salinity and reclamation

Authors: SEMIZ, GÜLÜZAR - ANKARA UNIVERSITY OF TURKEY; Suarez, Donald; LESCH, SCOTT - RIVERSIDE PUBLIC UTILITIES

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2022
Publication Date: 3/24/2022
Citation: Semiz, G.D., Suarez, D.L., Lesch, S.M. 2022. Electromagnetic sensing and infiltration measurements to evaluate turfgrass salinity and reclamation. Scientific Reports. 12. Article 5115. https://doi.org/10.1038/s41598-022-09189-7.
DOI: https://doi.org/10.1038/s41598-022-09189-7

Interpretive Summary: Water demands in arid regions are critical relative to supply, thus recreational turf for golf courses, sports fields and parks will increasingly have only degraded waters such as municipal treated wastewater and brackish ground waters for irrigation. The high cost and salinity of treated wastewater means that soil salinity and insufficient leaching needs to be closely monitored when these waters are used for irrigation. In this study we utilize electromagnetic sensing surveys with calibration to soil extracts to generate detailed salinity maps for golf course management of fairways irrigated with treated municipal wastewater. After evaluation of the initial survey we determined that leaching was needed for salinity reduction. After leaching, the field was resurveyed and new salinity maps developed. Analysis of the data indicated that salinity reduction was much less than expected based on volumes of water applied. Poor leaching was attributed to the practice of soil aeration, paradoxically used to improve water infiltration, causing bypass of leaching waters and reduced leaching of micropores. The use of EM as a practical tool for assessment of turf management is demonstrated. These findings are of interest to turf managers, irrigation extension specialists and water management researchers.

Technical Abstract: Scarce freshwater resources in arid and semiarid regions means that recreational landscapes should use recycled or low-quality waters for irrigation, increasing the risk of salinity and infiltration problems. We map salinity distribution within turf fields using electromagnetic sensing, evaluate need for leaching and evaluate post leaching results for subsequent management decisions. Electromagnetic measurements were made with two EM38 instruments positioned vertically and horizontally in order to determine salinity distribution. Sensor readings were coupled to GPS data to create spatial salinity maps. Next, optimal calibration point coordinates were determined via Electrical Conductivity Sampling Assessment and Prediction (ESAP) software. Soil samples from 0–15 and 15–30 cm depths were used for each calibration point. Laboratory soil saturation percentage, moisture content, electrical conductivity (ECe) and pHe of saturation extracts were determined for calibration to convert resistivity measurements to ECe. Next, ECe maps were created using ESAP software. Leaching for reclamation was performed by means of sprinkling. Treated municipal wastewater was utilized both for irrigation and for reclamation leaching. Low water content and high spatial variability of soil texture adversely affected the accuracy of the readings. Pre and post leaching surveys indicate that in one fairway there was only a 43% and 58% decrease in soil salinity at 0–15 and 15–30 cm depths, respectively which is very low relative to expected results considering the amount of water applied. This relatively low reduction in salinity and the lack of runoff during irrigation combined with infiltration measurements suggests that aeration techniques for healthier grasses led to water bypassing small pores thus limiting leaching efficiency. In this instance practices to improve infiltration lead paradoxically to less salinity reclamation than expected.