Integration of TOPSIS and Geostatistical Technique for Soil Quality Assessment under Different Land Uses: A Case Study

This study aims to assess the soil quality under different land uses by utilizing technique for order preference by similarity to the ideal solution method (TOPSIS) and geostatistical Technique in the Northern part of Sohag Governorate, Egypt. Various soil parameters such as sand, silt, clay content, CEC, ESP OC, ECe, pH, and CaCO3 were determined. Afterward, the geostatistics approach using ordinary kriging interpolation and semivariogram was applied to produce a spatialized and detailed map for each soil parameter. Spherical, Exponential, Gaussian, and J-Bessel geostatistical models were used to define the spatial variability of soil properties based on RMS, MSE, and RMSSE. Based on the TOPSIS method, the soil quality index (SQI) and its ranking under land use types in the study area were calculated. The results of SQI ranged from 38.75% to 55.82% and 27.53% to 52.72%, and 5.75% to 26.73% for old cultivated, new cultivated, and desert soil, respectively. The SQI was classified into three regions. The first has a fair quality index and covers 56.48% (403.91 km2) of the total geographical area (TGA). The soils of this region are located mainly in old cultivated soils and some new ones. The second region was observed in some newly reclaimed soils and desert soils and extended over an area of about 27.75% (198.45 km2). These soils have low values of favorable studied indicators, leading to negative effects on the SQI that are defined as poor. The third region is very poor quality, covers about 15.77% (112.78 km2) of TGA, and is located mainly in desert soils with low beneficial and high non-beneficial studied indicators. Finally, the results indicate that the integration of TOPSIS and geostatistical technique allow for an accurate and practical assessment of the SQI.