Conversion Factors for Electrical Conductivity of 1:5 Soil-Water Extracts to Saturated Paste of Reclaimed Tideland Soils are Affected by Sand Contents

Self Cite

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 (EC e ), exchangeable sodium percentage (ESP), and pH at 1:5 of soil:water ratio (pH 1:5 ). The EC e (range: 2.5 -15.8 dS m -1 ), ESP (1.6 -67.2%), and pH 1:5 (6.6 -9.0) of the RTL soils differed (P < 0.001) with RTL districts. Though there are indications of decreased EC e , ESP, and pH 1:5 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 (EC e < 4.0 dS m -1 , ESP < 15%, and pH 1:5 < 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.

Section: Soil Analysesmentioning

confidence: 99%

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

Seo,

Baek,

Park

et al. 2023

Self Cite

“…따라서, 습해 우려가 없고, 재배기간 동안 주기적인 관개로 일시적 제염이 용이한 벼 (Oryza sativa L.)를 주로 재배하고 있다 (Park et al, 2022). 하지만, 최근 쌀 소비량 감소 등에 의해 간척지 밭 작물 재배 필요 성이 증가하고 있어, 간척지 토양에서 사료작물 (Jang et al, 2020;Bae et al, 2021;Yun et al, 2021), 서류 (Lee et al, 2021a), 곡류 (Lee et al, 2021b;Oh et al, 2022) 등 다양한 작물 재배를 위해 토양 염농도 관리 기술 개발에 대한 연구 가 진행되고 있다 (Jeong et al, 2020;Seo et al, 2022).…”

Section: Introductionunclassified

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

Park¹,

Choi²

2023

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.

Soil Physico-Chemical Properties and Groundwater Levels at the “Agricultural Life Science Sites” in Saemangeum Reclaimed Land

Seo¹,

Jung²,

Jung³

et al. 2023

Self Cite

Typical reclaimed lands located in coastal areas including Saemangeum are not suitable for cultivation of upland crops due to a high salinity and groundwater levels and low nutrient contents. Therefore, for sustainable crop cultivation, it is necessary to soil salinity, water content, and nutrients that are necessary for development of land management for upland crops cultivation. In this study, we investigated physico-chemical characteristics of soils including pH, electrical conductivity (EC 1:5 ), organic matter contents, available phosphorus (Avail. P 2 O 5 ), and exchangeable (Exch.) cations concentrations, as well as bulk density, hardness, and soil texture. Soil samples were collected from soil layers up to 120 cm at 20 cm interval of survey fields (80 ha) of Saemangeum reclaimed land. Groundwater levels and soil water contents were also monitored. The EC (0.14 -0.51 dS m -1 ) was lower than those of other reclaimed land in South Korea, indicating desalinization across 120 cm of soil depth, and pH (5.5 -6.9) was also lower in accordance of the removal of non-acid cations through desalinization. Soil organic matter (1.5 -5.2 g kg -1 ), and nutrient (Avail. P 2 O 5 17.2 -35.5 mg kg -1 and Exch. calcium 0.8 -1.0 cmol c kg -1 ) contents were lower than the standard levels for upland crop cultivation (Organic matter: 20 g kg -1 , Avail. P 2 O 5 : 300 mg kg -1 , Exch. calcium: 5 cmol c kg -1 ). However, the soil hardness (15.1 -18.6 mm) was lower than the suitable level (21 mm) for crop cultivation. Meanwhile, water contents of top soil (0 -20 cm) were greatly changed by rainfall pattern; in particular, the soil located near the coastal areas had a large rise in groundwater level during rainfall. Our study provide key information on the changes in soil physico-chemical properties across soil depth for Saemangeum reclaimed land, which was necessary for development of land management practices for cultivation of upland crops.