Agricultural Water Salinity of Reclaimed Tidelands in Southwestern Coastal Areas of South Korea

Abstract

Monitoring of the salinity of agricultural soil and water is necessary for sustainable food production in saltaffected reclaimed tidelands (RTLs). Soil salinity has been extensively monitored; however, little attention has been given to water salinity. In this study, agricultural water salinity of five RTLs located in the southwestern coastal area of South Korea was monitored. A total of 215 water samples were collected from estuary lakes and inland streams in Bojeon (BJ), Goheung (GH), Gunnae (GN), Samsan (SS), and Youngsangang (YSG) RTLs in 2018, 2020, and 2022. Water samples were analyzed for electrical conductivity (EC w ) and sodium adsorption ratio (SAR) to estimate the suitability of water salinity for agricultural uses based on the FAO guidelines. The EC w (average: 1.6 -3.6 dS m -1 ) and SAR (5 -8) were highly variable being dependent on RTL locations, water type (lake and stream), and sampling year and month. For rice cultivation, EC w of BJ, SS, and YSG RTLs was lower than the threshold EC w (2 dS m -1 ) for rice growth; whereas EC w of GN (2.1 ± 1.0 dS m -1 ) and GH (3.6 ± 1.2 dS m -1 ) RTLs were higher than the threshold EC w . For upland crops cultivation, both EC w and SAR of five RTLs were much higher than the FAO threshold values (EC w < 0.7 dS m -1 and SAR < 3). Therefore, our results suggest that agricultural water salinity of the study RTLs is not suitable for cultivation of upland crop. Therefore, long-term monitoring of water salinity as well as developments of advanced irrigation-drainage are necessary for diversification of agricultural uses of RTLs.

Spatial Variations in Salinity and Sodicity of Reclaimed Tideland Paddy Soils in Coastal Areas of Southwestern Korea

“…In South Korea, EC of irrigation water has been reported to be 1.6 -3.6 dS m -1 (Park and Choi, 2023), which is lower than the EC e of most of the study fields (Fig. 2a).…”