Aluminum acidity soils

Inorganic reactions in the soil interstitial waters also influence dissolved P concentrations. These reactions include the dissolution or precipitation of P-containing minerals or the adsorption and desorption of P onto and from mineral surfaces. As discussed above, the inorganic reactivity of phosphate is strongly dependent on pH. In alkaline systems, apatite solubility should limit groundwater phosphate whereas in acidic soils, aluminum phosphates should dominate. Adsorption of phosphate onto mineral surfaces, such as iron or aluminum oxyhydroxides and clays, is favored by low solution pH and may influence soil interstitial water concentrations. Phosphorus will be exchanged between organic materials, soil inter-... 

D. L. Jones and L. V. Kochian, Aluminum-organic acid interactions in acid soils. 1. Effect of root-derived organic acids on the kinetics of A1 dissolution. Plant Soil 782 221 (1996). 

Phosphate reacts and forms insoluble compounds with many metals, particularly iron, aluminum, and calcium. Under acid soil conditions, both iron and aluminum become more soluble, and thus as soil pH decreases, its phosphate fixing power increases. This means that iron and aluminum react with phosphate to form insoluble species that are not available to plants. Under basic conditions, high concentrations of calcium exist and insoluble calcium phosphates form. Insoluble phosphate species are also formed with other metals that happen to be present however, the three mentioned are generally present in the highest concentration, and so they represent the major reactants with phosphate. Iron, aluminum, and calcium phosphates can also occur as coatings on soil particles. 

Hoyt PB, Nyborg N. Use of dilute calcium chloride for the extraction of plant available aluminum and manganese from acid soil. Can. J. Soil Sci. 1972 52 163-167. 

But Smith s research had relatively little impact on the scientihc community over the next seven decades. During this time, acid deposition continued to be of some minor interest to scientists in parts of Europe. For example, the Swedish biologist J. R. Erichsen-Jones reported in the late 1930s that acid from rainwater dissolved aluminum in soil and that that dissolved aluminum was toxic to certain types of aquatic organisms. 

Although iron, manganese, magnesium, calcium, and aluminum arsenates are usually too water soluble to control arsenic mobility in soils (Inskeep, McDermott and Fendorf, 2002), 187, iron, aluminum, or manganese arsenates occur in some acidic soils. In particular, scorodite may form from the partial weathering of arsenian pyrite or arsenopyrite (Inskeep, McDermott and Fendorf, 2002), 187. Calcium arsenates may be present in alkaline calcium-rich soils (Matschullat, 2000), 303 (Mandal and Suzuki, 2002), 204. 

Dolfing, J., W. J. Chardon, and J. Japenga. 1999. Association between colloidal iron, aluminum, phosphorus, and humic acids. Soil Science 164 171-179. 

Sivasubramaniam, S., and Talibudeen, O. (1972). Potassium-aluminum exchange in acid soils. I. Kinetics. J. Soil Sci. 23, 163-173. 

In addition to the effect of pH on mobility, the type of acid entering environmental systems may also be important. Nitric acid was found to leach more aluminum from soil columns representative of high-elevation forest floor soils than did sulfuric acid (James and Riha 1989). This is most likely due to the higher solubility of aluminum nitrate than aluminum sulfate. However, in mineral horizons below the forest floor, the study found that concentrations of aluminum leached by these acids did not differ from concentrations of aluminum leached by distilled, deionized water at a pH of 5.7. The authors concluded... 

Aluminum levels in soil also vary with different vegetation types. For example, aluminum levels in the soils of coniferous forests are often higher than in soils of beech forests since coniferous forests tend to have more acid soils (Brusewitz 1984). Alternate views of the data are that the acidic soil produced by conifers can preferentially mobilize aluminum from deeper layers toward surface soil, or that conifers over beech preferentially grow in soils rich in aluminum and it is their metabolic processes which produce more acidic soil. An analysis of aluminum in soils by depth could improve the understanding of this process. 

Jackson ML, Huang PM. 1983. Aluminum of acid soils in the food chain and senility. Sci Total Environ 28 269-276. 

Hargrove, W. L. and G. W. Thomas. 1981. Effect of organic matter on exchangeable aluminum and plant growth in acid soils. In Chemistry in the Soil Environment. Stelly, R. H. Dowdy,... 

Munns, D.N., Helyar, K.R., and Conyers, M., Determination of aluminum activity from measurements of fluoride in acid soil solutions, J. Soil Sci., 43, 441, 1992. 

Tan K. H. (1980) The release of silicon, aluminum, and potassium during decomposition of soil minerals by humic acid. Soil Science 129, 5-11. 

Watteau F. and Berthelin J. (1994) Microbial dissolution of iron and aluminum from soil minerals efficiency and specificity of hydroxamate siderophores compared to aliphatic acids. Euro. J. Soil Biol. 30(1), 1-9. 

Hudson M. J. and Sangster A. G. (2000) Aluminum localization in conifers growing on highly acidic soils in Ontario, Canada. In International Symposium on Impact of Potential Tolerance of Plants on the Increased Productivity Under Aluminum Stress. Research Instimte for Bioresources, Okayama University, pp. 103-106. 

Of the elements listed in Table II, most were found either to be relatively unchanged in their concentrations (e. g., sodium and potassium) or to decrease by 25-50% with increased depth. However, aluminum and calcium appear to increase (by 15-50%) with depth. Calcium and aluminum are often leached out of the upper levels of acidic soils, and pH at Yagi varies from slightly acidic in upper levels (5.5-6.0) to neutral in the lower levels (7.0). The highest concentration of calcium is found in Unit IV, at the archaeological horizon, and may be caused by the addition of calcium-rich remains such as animal bone. 

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