Soil physical properties, effect

Dinel, H., Schnitzer, M., Mehuys, G., 1990. Soil lipids origin, nature, content, decomposition and effect on soil physical properties. In Soil Biochemistry J.M. BoUag, and G. Stotzky (eds.), vol. 6, pp. 397 30. New York Marcel Dekker. 

Satchell (1967) emphasizes the role that earthworms play in organic matter transformations and concludes that on present evidence, conditioning plant remains for microbial decomposition seems to be the most important action of Lumbricidae in the ecosystem. Certainly these animals do increase the rate of decomposition of crop residues, and also have some effect on the ecology, but whether these effects are of greater importance than the effects on soil physical properties may be debatable. 

A variety of soil physical measurements can be used to evaluate the effectiveness of soil conditioners. These measurements include infiltration rate, air permeability, porosity, aggregate stability, penetration resistance, or bulk density. Reliable standardized procedures are needed to compare and/or evaluate the effect of soil conditioners on soil physical properties. For example, many companies rely on penetrometer measurements to evaluate their product, but do not standardize their measurements with respect to moisture content or bulk density. Such non-standardized observations may easily lead to erroneous claims about the product. Also, be cautious of studies relying on measurements that are not easily quantified such as soil tilth, stickiness, tightness, or hardness. 

Soil organics are also considered to be essential to the formation of stable aggregates in a wide range of soils. Physical properties of soil, such as structure and bulk density, are influence by the quantity and nature of complexes that form between organic and mineral matter. The physical characteristics of a soil are important to plant growth due to their effects on aeration, water penetration and retention, and mechanical impedance to... 

Ralston, C.W. Hatchell, G.E. Effects of prescribed burning on physical properties of soil Prescribed Burning Symp. Proc. USDA For. Serv. Southeast For. Exp. Sta. Asheville, NC, 1971 pp 68-85. 

Soils properties are very sensitive to the type of exchangeable ions. Calcium imparts favorable physical properties to the soil, while adsorbed sodium causes clay dispersion and swelling. It is generally recognized that an exchangeable sodium percentage of 10 is sufficient to cause soil dispersion, reduction of soil permeability and impaired growth of some crop plants. On the other hand, excess salt concentration prevents the dispersive effect of adsorbed sodium. 

Aggslides SM, Londra PA (2000) Effects of compost produced from town wastes and sewage sludge on the physical properties of a loamy and a clay soil. Bioresour Technol 71 253-259... 

Because they are not likely to move through the soil, very little will get into underground water. Mirex and chlordecone can stay in soil, water, and sediment for years. Both compounds are slowly broken down in soil, water, and sediment. Mirex is broken down more quickly than chlordecone. Mirex is broken down to photomirex, which can also cause harmful health effects. Photomirex is even more poisonous than mirex. It is produced when sunlight reacts with mirex in water or in the air. Fish or animals that live in waters that contain mirex or chlordecone, or that eat other animals contaminated with mirex or chlordecone, can build up these substances in their bodies. The amounts of mirex and chlordecone in their bodies may be several times greater than the amount in their prey or in the surrounding water. See Chapter 3 for more information on the chemical and physical properties of mirex and chlordecone. See Chapter 5 for more information on their occurrence and what happens to them in the environment. 

The assessment of health effects due to exposure to the total petroleum hydrocarbons requires much more detailed information than what is provided by a single total petroleum hydrocarbon value. More detailed physical and chemical properties and analytical information on the total petroleum hydrocarbons fraction and its components are required. Indeed, a critical aspect of assessing the toxic effects of the total petroleum hydrocarbons is the measurement of the compounds, and the first task is to appreciate the origin of the various fractions (compounds) of the total petroleum hydrocarbons. Transport fractions are determined by several chemical and physical properties (i.e., solubility, vapor pressure, and propensity to bind with soil and organic particles). These properties are the basis of measures of teachability and volatility of individual hydrocarbons and transport fractions (Chapters 8, 9, and 10). 

This work describes the application to soil of compounds of a previous study (11) which dealt primarily with organic synthesis and physical properties of reaction products of pure fatty acids with BETA. In this study derivatives were prepared from various industrial fatty materials. In addition, water infiltration studies on sand, sandy soil, and clay soils were carried out on the previously prepared and new compounds. Finally, an investigation was initiated to determine the biological effects of one water-repelling chemical, the partially hydrogenated tallow-fatty acid-DETA reaction product, on seed germination and plant growth. 

Table 8.3 Effect of volatilization on physical properties of residual kerosene. Reprinted from Galin Ts, Gerstl Z, Yaron B (1990) Soil pollution by petroleum products. Ill Kerosene stability in soil columns as affected by volatilization. J Cont Hydrology 5 375-385. Copyright 1990 with permission of Elsevier...

The microbial metabolic process is the major mechanism for the transformation of toxic organic chemicals in the subsurface environment. The transformation process may be the result of a primary metabolic reaction, when the organic molecule is degraded by a direct microbial metabolism. Alternatively, the transformation process may be an indirect, secondary effect of the microbial population on the chemical and physical properties of the subsurface constituents. Bollag and Liu (1990), considering behavior of pesticides, defined five basic processes involved in microbially mediated transformation of toxic organic molecules in the soil upper layer environment. These processes are described next. 

An example of the kinds of data required for land disposal options would be Information on soll/pestlclde Interactions to determine the effect of the pesticide on the soil and soil on the pesticide. The physical composition of the soil and the physical properties of the pesticide and Its formulation will determine the adsorption, leaching, water dispersal, and volatilization of the pesticide which. In turn, determine the mobility of the pesticide In soil. Even pesticides of closely related structures may have very different soil retention properties. Much of this data will be available from that developed to meet other registration data requirements with the exception that disposal rates are often orders of magnitude higher than normal application rates and the difference must be considered. 

Jozefaciuk, G. Muranyi, A. Fenyvesi, E. Effect of Randomly Methylated P-Cyclodextrin on Physical Properties of Soils. Environ. Sci. Technol 2003, 37, 3012-3017. 

Environmental Fate. Much of the environmental fate information on hexachlorobutadiene consists of modeling based on its physical and chemical properties and its similarity to related compounds. Further studies which determine the extent to which hexachlorobutadiene volatilizes from surface waters and soils, and the effects of organic-carbon content on this process would be helpful. 

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