Magnesium in soils

Official methods have been published for the determination of exchangeable and extractable magnesium in soils [131]. Magnesium is extracted from the soil with 1M ammonium acetate and determined by atomic absorption spectrometry. The determination of magnesium in soils is also discussed under Multi-Metal Analysis of Soils in Sects. 2.55 (atomic absorption spectrometry), 2.55 (inductively coupled plasma atomic emission spectrometry), 2.55 (photon activation analysis) and 2.55 (ion chromatography). 

Standing Committee of Analysts (DoE) (1979) The Analysis of Agricultural Materials-Magnesium in Soil Method 46, MAFF Technical Bulletin RB 427, HMSO, London, UK. 

D5. David, D. J., The determination of exchangeable sodium, potassium, calcium, and magnesium in soils by atomic-absorption spectrophotometry. Analyst 85, 495-503 (1950). 

The determination of sodium, potassium, calcium and magnesium in soil extracts [57] illustrates the implementation of this approach in a flow injection system. As these analytes are present in relatively high concentrations in the assayed samples, additions of diluent confluent streams were needed to increase dispersion. However, the total flow rate of the stream reaching the spectrometer was also increased, thus impairing nebulisation efficiency. This was circumvented by removing part of the sample carrier stream and the sampling rate was increased. In spectrophotometry, similar restrictions have been observed, especially when the increase in total flow rate impairs the development of relatively slow chemical reactions. 

A.R.A. Nogueira, S.M.B. Brienza, E.A.G. Zagatto, J.L.F.C. Lima, A.N. Araujo, Flow injection system with multisite detection for spectrophotometric determination of calcium and magnesium in soil extracts and natural waters, J. Agric. Food Chem. 44 (1996) 165. 

The concentration of magnesium in soils generally lies in the range between 0.5 g/kg for sandy soils and 5 g/kg for clay soils. The levels of magnesium are higher in clay soils due to the presence of weatherable ferromagnesian minerals, such as biotite, serpentine, and olivine and also the carbonate mineral dolomite. It is also present in secondary clay minerals, such as chlorite and vermiculite. 

Table 3. Exchangeable aluminum, calcium, and magnesium in soils from high elevation spruce-fir sites.

Cheng K-L, Hung J-C, Prager DH (1973) Extermination of exchangeable calciiun and magnesium in soil by ion-selective electrode method. Microchem J 18 256-261... 

Northern Californian soils have higher concentrations of Cr, Co, Cu and Ni than southern California since there are volcanic ultramafic rocks in northern California. Ultramafic rocks are mostly serpentine, a magnesium silicate with associated high amounts of Ni and Cr. Soils formed on serpentine parent materials contain high to extremely high Ni and Cr concentrations in soils. Soil parent material is a factor mostly controlling trace element concentrations in soils. 

Orthopedic devices, 3 721-735 joint replacement, 3 727-735 Orthopedic marrow needles, 3 743-744 Orthophosphate (PO4), in soil, 11 112 Orthophosphates, 18 830-841 20 637 magnesium, 18 839 manufacture of, 18 853-855 Orthophosphate salts, 18 836 Orthophosphoric acid, 18 815, 817-826 condensation of, 18 826 properties of, 18 817-819 solubility of boron halides in, 4 140t orf/zo-phthalic resins, 20 101, 113 formulation of, 20 102 Orthorhombic crystal system, 8 114t Orthorhombic phosphorus pentoxide, 19 49 Orthorhombic structure, of ferroelectric crystals, 11 95, 96 Orthorhombic symmetry, 8 114t Orthosilicate monomers, in silicate glasses, 22 453... 

The most common simple cations in the soil solution are calcium (Ca2+), magnesium (Mg2+), potassium (K+), and sodium (Na+). Other alkali and alkaline-earth elements, when present, will be as simple cations also. Iron, aluminum, copper, zinc, cobalt, manganese, and nickel are also common in soil. Iron is present in both the ferrous (Fe2+) and ferric (Fe3+) states, while aluminum will be present as Al3+. Copper, zinc, cobalt, and nickel can all be present in one or both of their oxidations states simultaneously. Manganese presents a completely different situation in that it can exist in several oxidation states simultaneously. 

One place where soil solution from saturated soils is routinely used is in the determination of salts in soil. Salts can build up in soil in low-rainfall areas. A measure of the salt content is essential for these soils. Typically, a saturated paste of soil is made and the water filtered by vacuum filtration. The filtrate can then be analyzed for electrical conductivity and this measurement, together with calcium, magnesium, and sodium content, can be used to calculate various measures of salt content and potential detrimental effects of salts on crops and water quality. 

In Procedure 11.10, step 1 is designed to extract soluble species, carbonates, and species on exchange sites. Step 2 is designed to extract reducible iron and magnesium oxyhydroxides. Step 3 extracts oxidizable organic matter and sulfides, while step 4 extracts any metals remaining after the completion of the previous extractions. Sequential extraction methods have also been used to extract and quantify the amounts of various arsenic species, primarily as As(III) and As(IV) in soil [21],... 

Soil. In soils, phosmet is rapidly hydrolyzed to phthalimide (Camazano and Martin, 1980 S nchez-Camazano and S nchez-Martin, 1983). The rate of hydrolysis is greater in the presence of various montmorillonite clays and chloride salts. The calculated hydrolysis half-lives of phosmet in the presence of calcium, barium, copper, magnesium, and nickel montmorillonite clays were 0.084, 0.665, 10.025, 16.926, and 28.738 d, respectively. Similarly, the half-lives of phosmet in the presence of copper, calcium, magnesium, and barium chlorides were <0.020, 5.731, 10.680, and 12.242 d, respectively. In comparison, the hydrolysis of phosmet in a neutral water solution was 46.210 d (Sanchez-Camazano and S nchez-Martin, 1983). 

Magnesium. From the standard graph determine the number of pg mM of magnesium in the sample, subtract the blank value and multiply the difference by 250 (initial extraction ratio of X5 multiplied by subsequent X50 dilution of the extract solution). The result is the number of mg extract-able magnesium in the air-dry soil. Include any extra dilution factors, and, if required, convert to oven-dry soil using the appropriate factor, as in Method... 

Beryllium in Plants and Animals. In 1888 F. Sestini found beryllium in land plants grown m soils containing it (92, 93). He found later that, although beryllium may take the place of magnesium as a nutrient for wheat, it is not a complete substitute for magnesium in the production of seed (93). Beryllium is occasionally present m bone (94). 

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