Transformation of soil

Information is contradictory about the contributions of root-derived C to the C pools available to the root zone and how this readily available C affects the subsequent associated microbial transformations of soil N (107). In a greenhouse experiment that involved growing maize plants and using C natural abundance and isotope "N techniques, 15% of the soil microbial biomass was derived from... 

Microbial Mediation of Weathering Transformation of Soil Minerals and Metal Dynamics... 

In addition to the factors considered for water, we need to consider for soil (a) the far greater importance of interactions with solid surfaces and the buffering of ions in solution by ions adsorbed on the surfaces and (b) the more-strongly reducing conditions that develop in soil because of the greater sink for O2, resulting in transformations of soil surfaces as well as of species in solution. 

Schwertmann, U. Taylor, R.M. (1973) The in vitro transformation of soil lepidocrocite to goethite. Pseudogley Gley, Trans. Comm. V VI Int. Soc. Soil Sd. Stuttgart-Hohenheim 1971 45-54... 

Almendros, G., Gonzalez-Vila, F. J., and Martin, F. (1990). Fire-induced transformation of soil organic matter from an oak forest. An experimental approach to the effects of fire on humic substances. Soil Sci. 149,158-168. 

Figure 9.1. Possible rate transformations of soil nitrogen. Terms k and kk denote rate coefficients e, s, p, i, and g refer to exchangeable, solution, plant, immobilized, and gaseous phases, respectively. [From Mehran and Tanji (1974), with permission.]...

Mazzola, M. Transformation of soil microbial community structure and Rhizoctonia-swppressive potential in response to apple roots. Phytopathology 1999 89 920-927. 

Figure 8.19 Full sequence transformation of soil organic matter in the geosphere (down to several kilometers) divided into the following stages of maturation (1) diagenesis (2) catagenesis and (3) metagenesis. (Modified from Tissot and Welte, 1984.)...

The phytoremediation process may be viewed as a symbiotic process between plants and soil microbes that involved in phytoremediation (Lasat, 2002). Plant and bacterial interaction can enhance the effectiveness of phytoremediation technology because plants provide carbon and energy sources or root exudates in the rhizosphere that will support microbial community in the degradation and transformation of soil pollutants (Siciliano and Germida, 1998). In addition, the presence of soil microbes can increase the water solubility or bioavailability of pollutants in soils, which facilitates the uptake of pollutants by plants (Lasat, 2002 Siciliano and Germida, 1998). However, the specificity of the plant-bacteria interactions besides being much intricate is dependent upon soil and the aqueous conditions, which can alter contaminant... 

The previous Sections have dealt with the chemistry, abundance, and transformation of soil carbohydrates, with little reference to the larger system, soil, in which they occur. The carbohydrates are in intimate contact with other organic and inorganic soil constituents and enter into interactions with them. Such interactions have an influence on the behavior of carbohydrates on the one hand and on soil properties and plant nutrition on the other. 

Correlations between concentrations of dissolved metals (iron and/or aluminum) and of either DOM or organic acids in infiltrating waters suggest that DOM, or some component of DOM, facilitates metal solubilization and translocation in soils (14). The role of DOM in metal mobilization is also supported by the occurrence of organically complexed metals in soil solutions (3, 15, 16). Precipitation and transformations of soil minerals can be inhibited by DOM, which tends to stabilize metastable phases [such as amorphous aluminum hydroxide and pseudoboehmite (17), ferrihydrite (18), and octacal-cium phosphate (19)] and to prevent formation of more crystalline phases. 

Flood irrigation was found to cause a rather rapid irreversible transformation of soil elay minerals and loss of potassic minerals (in 30 years or less) despite the use of fertilizers. 

Tyutyunov, I.A. Changes and Transformations of Soils and Hard Rocks at Negative Temperatures (Cryogenesis), Akad. Nauk SSSR. Moscow, 1960,144 pp. 

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