Soil origin

Miethling R et al (2000) Variation of microbial rhizosphere communities in response to crop species, soil origin, and inoculation with Sinorhizobium meliloti L33. Microb Ecol 40 43 Gray ston S J et al (2001) Accounting for variabUity in soU microbial communities of temperate upland grassland ecosystems. SoU Biol Biochem 33 533... 

Exposure from terrestrial radionuclides present at trace levels in all soils are specific and relate to the types of rock from which the soils originate. Higher radiation levels are associated with igneous rocks, such as granite, and lower levels with sedimentary rocks. There are exceptions, however, as some shales and phosphate rocks have relatively high contents of radionuclides. Radon and its short-lived decay products in the atmosphere are the most important contributors to human exposure from natural sources. 

Two particular aspects of the transport of degradable contaminants were considered in laboratory experiments that used soil originating from the field experiments described in the previous sections. Studies on diffnsion of degradable insecticides were performed in diffusion cells, while the spatial redistribntion of pesticides from a point source was measured in specially designed pans (60 cm high, 40 cm diameter). Periodic sampling and contaminant analysis enabled visnaUzation of the contaminant transport pathway. 

To the extent that diet contributes to internal body burdens, a comparison of the relative plant uptake of actinides from soil is of interest. Several studies have compared the uptake of various transuranium elements by plants (17,18,19). However, studies which include U and Th are not as available. Figure 2 presents recent results for field-grown vegetation of soil originally contaminated in 1944 with soluble forms of U, Th and Pu (and daughter Am) (20.21). The crops examined include soybeans, snapbeans,... 

Zavarzina, A. G. (2001). Sorption of soil-originated humic acids on clay minerals, Proceedings. Eleventh Annual V. M. Goldschmidt Conference, May 20-24, Hot Springs, Va. 

The use of compositional analysis should assist in the differential separation of several sources of soil, such as the soil that builds up on shoes, vehicle tires, and implements used to bury objects or bodies. This, in addition to identifying locations of mixed soil, can potentially separate out different soil horizons. This method has been applied in both sourcing vegetation and solutes and can tease apart several sources when present in a mixture (Brewer et al. 2005), with much potential in the application of mixed soil origins. However, the robustness of any unmixing solution depends on the number of samples, number of source groups, and the variance of the source group properties (Small et al. 2004). 

Technical DDT is composed of about 4% TDE (8), which corresponds to the ratios shown in Tables II and III. This result suggests that the TDE found in the orchard soils originated in the technical mixture applied to the crop and not by microbial action in the soil, as recent reports might indicate (1,5),... 

While the value of applying various amendments to j icultural soils was recognized and practiced for over 100 centuries, serious scientific inquiry into the mineral nutrition of plants did not begin until early in the 18th century. Most of the results of these early experiments were misinterpreted, principally due to the underdeveloped state of chemistry. The famous experiment of van Helmont (1577—1644) is a case in point. He placed 90.8 kg of soil in an earthen container, moistened the soil, and planted a willow shoot weighing 2.3 kg. After 5 years the tree weighed 76.7 kg, and he could account for all but 57 g of the 90.8 kg of soil originally used. Since he had added only water, he concluded that water was the sole nutrient of the plant and attributed the loss of the 57 g to experimental error. 

A Inherent Biodegradability in Soil (original guideline, adopted May 12, 1981)... 

The typical Clarendon profile consists of a dark grayish-brown, sandy horizon underlain by a yellowish-brown, sandy clay loam horizon, which is underlain by a mottled yellowish-brown, red, and gray, sandy clay loam horizon that contains 5 to 30 percent plinthite. Clarendon soils originate from unconsolidated sediments of medium texture. They are typically found on uplands and have a slope gradient of less than 2 percent. The soils are moderately well drained and have slow runoff. The upper part of the soil profile is more permeable than the lower part. 

Abiotic toxic damages to cultured and wild plants may result from natural geochemical loads in the soil originating from salt or certain trace elements in water, the vicinity of volcanoes, or natural atmospheric pollution. As a rule, however, the cause is anthropo-... 

Typical soils exhibiting distinctive layers with increasing depth are called horizons (Fig. 9.7). The top layer, normally several centimetres in thickness, is known as the A horizon, or topsoil. This is the layer of maximum biological activity in the soil and it contains most of the soil organic matter. Metal ions and clay particles in the A horizon are subject to considerable leaching. The next layer is the B horizon, or subsoil. It receives material such as organic matter, salts, and clay particles leached from the topsoil. The C horizon is composed of weathered parent rocks from which the soil originated [1]. 

Pedogenesis Soil origin. Mineral formation within the soil. 

Soil Original soil K-soil NH4-soil Ca-soil Al-soil Fe-soil... 

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