Red Mediterranean Soils: Nature, Properties, and Management of Rhodoxeralfs in Northern Greece

The studied Alfisols were developed on Quaternary calcareous deposits and belong to the great group of Rhodoxeralfs. They occur usually in the meso-Mediterranean bioclimatic zone and are affected by water deficit during the summer period. They are located mainly on backslope geomorphic surfaces, old terraces, and alluvial fans, and their erodibility is medium to low. Trends of decreased iron content in the deeper soil layers due to severe drainage conditions may be responsible for relatively low values of free iron oxides (Fed). The rather limited variation of Fed may reflect the specific pedogenetic conditions in which red soils were formed. Indices of pedogenesis [Feo/Fed (Feo: amorphous Fe), Fed-Feo, and iron illuviation index of Fed] indicated that the studied pedons are at different stages of development. Redness indices (RI) of Bt horizons in pedons were found in the following decreasing order: P1 = P5 P4 = P6 P2 P3. There were no clear trends of free manganese oxide (Mnd) distribution with depth. The lack of correlation between Mnd and clay or Fed suggested that Mnd oxides do not take part in the co-illuviation of clay and Fed oxides. Acidity, low content of organic carbon, exchangeable potassium (K+), available phosphorus (P), and water deficit are the main impediments to crop production on these soils. Geomorphological and physicochemical properties suggest that rotation schemes, minimum tillage, liming practices, soil leveling, use of proper irrigation systems, and micronutrient application are among the suggested practices to sustain crop production and mitigate erosion risk.