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Soil Mechanics
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Several soil classification systems see widespread use today. They provide a way for engineers, soil scientists, and others to describe various kinds of soils that may be appropriate for different uses. These systems reflect different purposes and provide different information. The most widely used systems in North America are the United States Department of Agriculture (USDA) Soil Classification System, the USDA Soil Taxonomy, and the Unified Soil Classification System (USCS). Some government agencies in the United States have established their own classification systems, as have many foreign governments and agencies. The USDA Soil Classification System and Taxonomy were discussed in the Chapter 11. Here, we look at the USCS system because it has more implications for soil properties and engineering.
Erodibility of Two Soft Limestone Road Bases under Tropical Rain
Published in Mark Anglin Harris, Confronting Global Climate Change, 2019
A high proportion of silicates have been leached out of the soil to leave residual deposits that are rich in iron hydroxides and oxides (Jordán 2014), and oxidizing conditions produced the characteristic red color. Such areas are usually depressions or cracks within the limestone (Muhs and Budahn 2009). The UNESCO/FAO Soil Map of the World equivalents are the chromic luvisols (a sub-order of the luvisols), and the USDA soil taxonomy equivalent is the rhodustalfs (a sub-order of the ustalfs) (Allen 2001). Compared to most clay soils, Terra Rossa has surprisingly good drainage characteristics (Waugh 2000) due to the strong development of its structure. Thus, for several calcareous Thailand soils, Tawornpruek et al. (2006) found that the dominantly kaolin sesquioxide mineralogy gives rise to high aggregate stability.
Evaluation of phytoremediation capability of French marigold (Tagetes patula) and African marigold (Tagetes erecta) under heavy metals contaminated soils
Published in International Journal of Phytoremediation, 2022
Biswojit Biswal, Satish Kumar Singh, Abhik Patra, Kiran Kumar Mohapatra
To perform the greenhouse pot experiment, bulk soil samples (0 − 18 cm) with varying physico-chemical properties were collected from nine different locations of Varanasi and Mirzapur districts of eastern Uttar Pradesh (Table 1). The soil samples were red soil (RS), black soil (BS), alluvial soil (AS), recent river clay soil (RRCS), sewage irrigated soil (SIS), garden soil (GS), municipal sewage sludge (SS), sandy soil (SAS) and usar soil (US). According to USDA Soil Taxonomy the red soil was classified as Alfisol, black soil as Vertisol, alluvial soil, sewage irrigated soil, garden soil and usar soil as Inceptisol, and recent river clay soil and sandy soil as Entisol. These nine different soil samples were air-dried, ground to pass through 2 mm sieve, and 4 kg of soil was filled in polythene lined pots which served as heavy metals untreated soils. Another set of polythene lined pots containing nine different soil samples were treated uniformly with lead (20 mg Pb kg−1 soil), cadmium (5 mg Cd kg−1 soil), chromium (30 mg Cr kg−1 soil) and nickel (10 mg Ni kg−1 soil). Heavy metals for 4 kg soil were calculated and applied in liquid form using lead sulfate (PbSO4), cadmium sulfate (CdSO4·8H2O), potassium-di-chromate (K2Cr2O7) and nickel sulfate (NiSO4·7H2O) as a source of Pb, Cd, Cr, and Ni, respectively. Before planting, the treated soils were irrigated to field capacity and retained in the net-house for one month so that added metals (Pb, Cd, Cr, and Ni) could equilibrate with soil.