considerable information exists in the literature showing that expansive layer silicates are not the only clay minerals present in vertisols. however, the presence of a very high clay content dominated by fine clay, regardless of the clay type, together with the wetting and drying cycle in the soil can also produce a high shrink-swell potential. we studied some vertisols with diverse parent mat...

This chapter presents an overview of how field-based methods quantify the processes shaping upland, soil-mantled landscapes. These methods have been applied across diverse field areas, ranging from the tropical sandstones of northern Australia to the alpine granites of the Sierra Nevada in California. In all cases, the landscapes examined through such work are relatively gently sloping with a g...

pedogenesis and clay mineralogy of soils and rock samples were studied in a transect of calcareous, gypsiferous, saline soils and sediments of bakhtegan lake bank in southern iran. the main objectives of study were to determine the occurrence of clay minerals and factors controlling their distribution pattern and relative abundance in soils and parent materials. the soil parent material is high...

Nineteen soil samples (SE Spain) with very different chemical physical properties and developed over different parent materials were contaminated by adding increments of an acidic solution from oxidised pyrite tailings. The quantities of Cu, Zn, Cd and Pb precipitated by the soil samples were directly and significantly related to the pH-buffering capacity. However, when the contamination caused...

Phosphorus (P) and sulfur (S) in soil and parent material are important in the accumulation of nitrogen (N) and organic carbon (C org ) in soils. In an observational study, the role of P and S in soil development was explored on a small knoll in the Wasatch subalpine summer range of central Utah that had been severely eroded during uncontrolled grazing in the late 1800s. Vegetation, litter, soi...

Many soils have clay-enriched horizons that are thought to result from pedogenic processes. Various hypotheses are proposed for expected clay size-distributions in soil profiles. The average size of clay crystallites determined by the amount of broadening of x-ray diffraction peaks ranged from 160 to >2000A 0 , but the lack of trends in four loess-de• rived soils did not permit the hypotheses t...

Trace elements mean elements present at low concentrations (mg kg-1 or less) in agroecosystems. Some trace elements, including copper (Cu), zinc (Zn), manganese (Mn), iron (Fe), molybdenum (Mo), and boron (B) are essential to plant growth and are called micronutrients. Except for B, these elements are also heavy metals, and are toxic to plants at high concentrations. Some trace elements, such a...