Evaluation of Land Degradation Status of Soil Series Using Geomatics Techniques

This study aimed assessing the land degradation status of some soil series of the North Tikrit Agricultural Project using remote sensing data. Part of the project area (246,555) km2 was selected based on variations in soil characteristics and agricultural crops. The study area is located between the longitudes of 43˚ 12′ 30ʹʹ and 43˚ 27′ 30ʹʹ E and the latitudes of 35˚ 15′ 00ʹʹ  and 35˚ 0′ 00ʹʹ N. This project area includes five soil series: Hatra, Jareesh, Safa, Seneyah, and Shurqat. Forty-four soil samples covering these five soil series were collected from the surface layer (0-30 cm). The chemical properties of these samples were determined, including pH, Electric Conductivity (EC), calcium carbonate content, gypsum content, cation exchange capacity, and organic matter content. Two Landsat satellite images were employed for calculation of soil and vegetation spectral indices. One of these two images was acquired on 15 June, 2002 while the other was acquired on 25 June, 2022. The spectral indices of concern encircled three vegetation indices (Advanced Vegetation Index (AVI), Specific Leaf Area Vegetation Index (SLAVI), and Structure Insensitive Pigment Index (SIPI)) and three soil spectral indices (Bare Soil Index (BSI), Modified Bare Soil Index (MBSI), and Normalized Difference Bare Soil Index (NDBSI)). The results show that there are variations in the values of the various computed soil and vegetation spectral indices during the two study periods and that the values were, in general, lower in 2022 than in 2002. It was found that the soils were degraded and that, consequently, the plant density declined during the study period. This had negative impacts on the fertility and productivity of the soils in the study area. The results also showed differences in the soil spectral reflectivity curves, especially at the wavelengths of water absorption; 1.4, 1.9, and 2.2 μm, due to the presence of gypsum at high concentrations in the soils.