Water retention and irrigation characteristics of Vertisols in northwestern Turkey

Abstract

The study comprised the analyses of 105 soil samples, located across the Thrace region of Turkey, collected from the horizons and sub-horizons of 16 soil pedons, classified as the Haploxerert and Calcixerert Great Groups of the Vertisol Order. Fundamental soil hydraulic and irrigation management properties, such as water retention and infiltration rate of the soils were evaluatedd along with the content and type of the dominating clay mineral. Results obtained for the major properties related to irrigation management such as the total total water holding capacity (TWHC), total available moisture (TAM) and the final infiltration rate of the studied soils, showed close dependence on the varying clay contents and clay types, and varied in the ranges of 393 and 635 mm/100 cm; 128 and 244 mm/100 cm; and 1.0–80.0 mm/h, respectively. In addition, it was determined, that values of the studied hydraulic characteristics are influenced also by the relative abundance and crystallinity degree of the dominant and accompanying clay mineral; availability of cracks, hard pans, self-mulching (pedoturbation) and gilgai formation. The diversity of the morphological, physical and/or chemical properties revealed that the studied soils required distinctive approaches and techniques in terms of irrigation management. The Türkgeldi Vertisol (Türkgeldi State Farm D11 and D12 locations) is an appropriate example for decreased pedoturbation and/or maturation in physical pedogenesis and in turn development of a stable soil structure, despite the high clay size particle and ssmectite contents throughout the profile.