Geostatistical models for land capability evaluation of Wadi Tag El-Wabar, Sohag, Egypt

This study aims to evaluate the land capability and assess geostatistical models for some soils of Wadi Tag El-Wabar located at south-western of Sohag governorate, Egypt. The investigated area is a part of the western desert; it is lies between latitudes 26◦ 3′ 50″ to 26◦18′ 00″ N and longitudes 31◦ 33′ 00″ to 31◦ 45′00″E. According to geomorphological units and recent digital image, thirty soil profiles were chosen to represent the studied area. The obtained results indicated that Wadi Tag El-Wabar soils are included four capability classes i.e. Grade 2 (Good), Grade 3 (Fair), Grade 4 (Poor) and Grade 5 (Non-agricultural) that represents 4.13, 30.07, 34.92 and 30.88%, respectively, of total area, by applying modified Storie rating. Geostatistical analysis for land capability rates were calculated through variance structure using eight semivariogram models (Circular, Pentaspherical, Exponential, Gaussian, Rational Quadratic, Hole Effect, K-Bessel and J-Bessel). All geostatistical models were fitted to the experimental semivariogram analysis using two kriged types (Kriging and Co-Kriging). These models were evaluated by five prediction errors i.e. mean, root mean square, average standard error, mean standardized and root mean square standardized. The results showed that Hole Effect and J-Bessel models were the best used models. A positive correlation (r2 = 0.7933) was recorded between the Hole Effect and J-Bessel semivariogram models.