WATER-RETENTION CAPACITY IN FINE EARTH AND GRAVEL FRACTIONS OF SEMIARID MEDITERRANEAN MONTANE SOILS

Water retention capacity was studied in fine earth and gravel from loa my-textured soils with medium-low carbon content in a semiarid Mediter ranean montane location, Sierra Gador, southeastern Spain. In fine ear th, typical water retention curves were established at six soil water potentials (-10, -33, -100, -500, -1000, and -1500 kPa), and the water retention was compared against different physical, chemical, and mine ralogical properties. Percent total sand and organic carbon content we re the variables that gave the best fit in the pedotransfer functions for the calculation of water retention at -33 and -1500 kPa. Results f or water retention in gravel at -33 and -1500 kPa show that gravel can make a significant contribution to the available water in the soil. B ulk density of gravel was the property most closely related to water c ontent at both soil water potentials, and rc as the variable that gave the best fit in the pedotransfer functions. Other properties that wer e useful with this function were citrate-ditionite extractable Fe cont ent, quartz, feldspathic, and phillosilicates content. In semiarid env ironments, the greatest differences in water retention are found betwe en soils derived from different parent materials, regardless of their taxonomic relation.