Comparison of Saturated Hydraulic Conductivity under the Reclaimed Conditions of Salt Affected Soil

Abstract

Solving the soil problems that affect negatively on growth of plants and reduce the soil permeability is necessary for the study site, Thein Gone Village in Yamethin Township, Myanmar. The objectives of this study were; to identify the soil whether it is salt-affected or not and to investigate the proper reclamation method with different rates of amendments by comparing the saturated conductivity (Ks). Both composite (disturbed) and core (undisturbed) soil samplings were collected at three profiles (0 - 60 cm soil depth) during March, 2023. Some soil properties such as texture, bulk density (g cm-3), moisture content (%), ECe (electrical conductivity, saturated extract; mS cm-1), pH (1:5 water), SAR (sodium absorption ratio) and pH and EC of leaching water were also measured. Firstly, the study site was problematic with high pH due to Na+ distribution of underground water although there was some application of gypsum for a decade. Also, low permeability (Ks < 1x10-8 cm s-1) was another problem there. To leach the salt (EC < 1 mS cm-1 in leachate), 1500 cm3 of water was necessary for one core (98.21 cm3 soil volume). It was relatively high amount for using the quality-water. For reclamation methods, gypsum 5 t ha-1, sulphur 1 t ha-1, and cow-dung manure 20 t ha-1 gave the minimum (- log Ks) value among different rates of each amendment. The less the - log Ks, the more permeable the soil becomes. Among different amendments, gypsum 5 t ha-1 showed the fastest saturated hydraulic conductivity. Moreover, it is necessary to drain out the leachate to prevent the formation of saline -sodic soil.