Red soils of Thrace (Greece): Properties, development, and productivity

Soil mapping and classification of the agricultural land in regions of Thrace (Northern Greece) revealed that red soils in this province constitute a significant. portion of the total agricultural land, supporting several land utilization types. The study area is located in the meso-mediterranean bioclimatic zone and the soils' moisture regime is xeric. These red soils were developed on Quaternary calcareous deposits and belong to the great groups of Rhodoxeralfs, which are the majority of the studied soils, and Xerorthents. They occur on well-drained sites, mainly on shoulder and backslope geomorphic surfaces, they have been affected by erosion and in some cases the argillic horizons of the Rhodoxeralfs have being exposed at the surface. The depth distributions of iron and manganese oxides indicate that these red soils are probably at a high development stage. The significant correlation of free iron oxides (Fed) to redness rating (RR) and the pedogenetic environment, that favors the formation and stability of hematite, leads to the assumption that in the studied red soils hematite is the predominant iron oxide responsible for soils red coloration. Field observations and laboratory analyses suggested that red soils of Thrace are of low to medium productivity and erosion control, soil water conservation, minimum tillage, preservation of organic matter and the use of non-acidifying fertilizers should be practiced to improve their productivity.