The Study area is located in the Eastern Anatolia. Erzurum Basin is one of the most important tectonic depression of the Eastern Anatolia, and an elevation of the basin is about 1750-2000 metres and it covers an area of 825 km2, and total study area is nearly 2015 km2. The Erzurum basin is enclosed by Dumlu Mountain on the north, by the Palandöken Mountains on the south and by the Kargapazari M. on the east. The mountains of the given area are completely composed of volcanic rocks such as andesites, dacites, trachytes and basalte while Neogene and Quaternary sediments are common in the basin; the Upper Miocene sediments, occur on the NW p a rt of the basin, the Plic-quatemary sediments were entirely accumulated in the basin, and this formation is composed of the layers of clay, marly, limestone and the deposits of sand and gravel. Quaternary alluvions are widespread on the central part of the plain; dejection fans and cones a re also occur the edge of the basin.
The Mountain ranges begin a t an elevation of about 2000 metres near the basin and rise up to 3000 metres. The slopes of the ranges toward the basin, are very steep and this steep slopes were deeply dissected by the streams. On the other hand, on the plainward side of the rangres there are esorional surfaces in the different elevations which were developed neogene lake level. There are also fault scarps, extending in a NE-SW direction, is about 200-250 metres from the basin surface.
The upper p a rt of the ranges, basaltic plateaus are common. According to the Erzurum Meteorological Station data (1929-79), mean annual temperature is 5.9°C, and mean annual precipitation, is about 456 mm. The natural vegetation of the basin is steppe, and the sub-alpine and the alpine vegetations are common upper p a rt of the mountains. SOIL : The terminology and classification system is in conformity with that used in 1949 system USA an d /o r in the Soil Survey Manual.
Zonal Soils : The soils are developed on the flat neogene sediments and the old dejection fans o r bajadas. The Brown soils are generally moderate deep and loam texture, in the B horizon clay and CaC03 accumulations are common; pH of these soils notral and medium alkaline. Chestnut soils are formed on the volcanic rocks at about 2000 metres. The lime was completely leachled both A and B horizon and accumulated in the upper layer of C.
Intrazonal soils : The soils of the central p a rt of the basin, and upper surfaces of the ranges are belong to intrazonal soils. The hydromorphic soils are found on the lower level of the basin. A horizon is rich in organic matter; pH of the soils vary from 6 to 7, and gley horizon and massive stru c tu re are observed. Saline and alkaline soils (Solonetz) are found especially near the Karasu River and lower part of the basin where high watertable areas. Salt an d alkaline materials efforencence quickly develops a t the topsoil and the surface due to high evaporation during the summer period. The pH of the soils very from 8.2 to 9.7, and the CaC03 contents range from 4 to 20, and the electrical conductivity in mmho/cm at 25°C is about between 1.6-10.6. The organic soils are common on the swamp areas of the basin. Rendsinas are being developed on the soft limestone and the marl deposits. The Alpinemeadow soils are occur on the basaltic plateaus in the ranges, CaC03 completely leached along the profile.
Azonal soils are lithosol, alluvial and colluvial. Lithosol are observed on the steep slopes of the ranges. Colluvial soils are covered old dejection fans and the soils are relatively deep and have a coarse texture near the fan apex gradually. becoming sandy loam and loam near its borders. Alluvial soils are only weakly developed and the profiles are often stratified. The soils of the study area were affected by the prevailing climatic conditions and geomorphological agents.
