Short-Scale Soil Spatial Variability of a Salt-Affected Land Allotment in <em>Maha-Illuppallama</em>, Sri Lanka

Abstract

The development of salt-affected soils is a serious limitation for sustainable agricultural crop production in Sri Lanka. This study was conducted to explore the short-scale spatial variability of a salt-affected land allotment at Maha-Illupallama in dry zone, Sri Lanka. Seventy soil samples from a depth of 0 - 30 cm were randomly collected within the study site. Soil Electrical Conductivity (EC), pH, Cation Exchange Capacity (CEC), Exchangeable (Ex.) cations; Ex.K, Ex.Na, Ex.Mg and Ex.Ca were measured using established techniques. Sodium Adsorption Ratio (SAR), Exchangeable Na percentage (ESP), K (EPP), Mg (EMP), and Ca (ECP) were estimated based on the relevant measured soil properties. Exploratory data analysis found considerable spatial variability in EC, ESP, SAR, and EPP while CEC, EMP, and ECP showed moderate spatial variability. The soil pH and BS exhibited lesser spatial variability within the study field. Variogram analyses revealed the presence of strong structured spatial variability for each analyzed soil parameter within the study site. Four Potential Management Zones (PMZs) i.e., PMZ1, PMZ2, PMZ3, and PMZ4 were demarcated using Fuzzy k means classification. Highest EC (1.19 ± 0.70 dS m-1) and SAR (19.05 ± 13.09) mean values were observed in PMZ2. Higher EMP mean values were observed in PMZ 1 and 3 in comparison to PMZ 2 and 4. Other evaluated soil properties varied among the designated PMZs. Soils in several places revealed pH > 8.5, EC < 4.5 dS m-1, ESP > 15%, and SAR > 13 values indicating an occurrence of sodic soil. The results underline the considerable potential for the use of Site-Specific Soil Management (SSSM) practices based on the PMZs in the examined salt-affected soil to boost productivity.