Assessment of salt-affected soil extent and spatial variability using GIS and remote sensing in Asaita district, Northeastern Ethiopia

Abstract

Salt-affected soils critically affecting irrigation practices and crop production, and also improper irrigation practices aggravated soil salinity problems in Asaita District. This study was conducted to assess the magnitude and spatial variability of salt-affected soils in the irrigated areas of Asaita District, Afar Region, Northeastern Ethiopia using GIS and remote sensing techniques. To undertake this study, base map of land use/ land cover were created based on desk review of existing document, initial data using ARC GIS 10.3 software and Google earth imagery. Soil samples were collected and analyzed for its selected physichochemical properties. A total of 100 surface soil samples (0-30 and 30-60 cm depth) were collected randomly from each stratum, with locations recorded using GPS. Additionally, 104 samples were collected from six soil profiles.The findings revealed that soil salinity is a critical issue, affecting 100% of the study area, with 69.85% classified as saline and 30.15% as saline-sodic soils. The spatial analysis indicated that soil salinity (ECe) exhibited strong spatial dependence, whereas sodicity (ESP) showed weak spatial dependency, and soil pH had moderate spatial dependence. The primary drivers of soiol salinity were found to be excessive irrigation, poor drainage systems, and low-quality irrigation water, leading to salt accumulation in the soil profile. Improved irrigation practices and drainage interventions reduced surface salinity by 25-30%, potentially reclaiming over 3,500 ha of marginal land. These results highlight the urgent need for sustainable soil and water management practices to prevent further land degradation and ensure long-term agricultural productivity.