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

Reclaimed tidelands (RTLs) in the southwestern coastal areas of South Korea has been used for rice (Oryza sativa L.) cultivation due to high salinity of the soils. However, there is increased social pressure to utilize the RTLs for upland crop cultivation due to decreased rice consumption. In this study, salinity and sodicity of 16 RTLs located were investigated to explore the suitability of RTLs for upland crop cultivation. Surface (0 - 20 cm) soil samples were collected from 241 paddy fields in the 16 RTL districts and analyzed for electrical conductivity of saturated soil paste extracts (ECe), exchangeable sodium percentage (ESP), and pH at 1:5 of soil:water ratio (pH1:5). The ECe (range: 2.5 - 15.8 dS m-1), ESP (1.6 - 67.2%), and pH1:5 (6.6 - 9.0) of the RTL soils differed (P < 0.001) with RTL districts. Though there are indications of decreased ECe, ESP, and pH1:5 with rice cultivation year after reclamation, this pattern was not statistically significant, suggesting that land management practices such as liming and organic matter application are required to facilitate desalinization and desodification of RTLs. Of the 16 RTLs, normal soils (ECe < 4.0 dS m-1, ESP < 15%, and pH1:5 < 8.5) were found in seven RTLs including Wolchen, Sanae, and Baiksoo RTLs. The proportion of normal soils in these three RTLs were 75%, 56%, and 47%, respectively. Therefore, these RTLs are found to be more suitable for upland crop cultivation than other RTLs. However, because the growth of upland crops are also susceptible to soil moisture stress, more information such as groundwater levels and soil drainage is required for successful upland crop cultivation in these RTLs.Distribution of normal, saline, sodic, and saline-sodic soils for paddy fields in the reclaimed tidelands located in southwestern coastal area of South Korea.