Calcium chloride extracts

Calcium Chloride Extraction - A o.oi M calcium chloride solution extraction. 

B. Seeling and A. Jungk, Utilization of organic phosphorus in calcium chloride extracts of soil by barely plants and hydrolysis and alkaline phosphatases. Plant Soil 178 119 (1996). 

Calcium chloride extractant, 0.01 M - completely dissolve 1.47 g CaCl2.2H20 in water and make up to 1 I. 

Calculation. The 25 g soil was shaken with 50 ml calcium chloride extractant, and 25 ml of this extract was diluted to 50 ml. There is therefore a x4 dilution factor. Calculate the concentration of SO -S in the blank and samples by comparison with the standard curve. Subtract the blank value from the sample values and multiply by 4 to give the pg SO -S g (= mg SO -S kg- ) air-dry soil. Include any extra dilution factors, and, if required, convert to oven-dry soil using the appropriate factor, as in Method 5.2, Calculation (2). 

Bickford and Willett [59] have pointed out that the filtration of aqueous calcium chloride extracts of soils containing phosphate through Gelman 9A6 cellulose acetate membranes which contain a wetting agent caused low results in methods for determining phosphate, due to the presence of some contaminant in the membrane. Gelman TCM-450 or Whatman No 42 membrane, on the other hand, does not interfere in the determination of phosphate. 

Whitten, M.G. and Ritchie, G.S.R (1991) Calcium chloride-extractable cadmium as an estimate of cadmium uptake by subterranean clover. Austral. J. Soil Res., 29, 215-221. 

West and co-workers11 achieved far greater sensitivity enhancement by trapping readily atomized elements, which had been nebulized conventionally for periods of up to a few minutes, onto the outer surface of a small bore, water-cooled quartz tube. If the water was then drained rapidly, the tube temperature quickly rose and the element was atomized off the surface. For cadmium in calcium chloride extracts of soil, for example, a detection limit of 4 ng (g soil) -1 was reported. A water-cooled double silica tube atom trap similarly has been very successfully employed for the determination of cadmium and lead in natural waters by flame AAS.12 Some further examples of applications of atom trapping are included in Chapter 7. 

McBride, M. B., Nibarger, E. A., Richards, B. K., and Steenhius, T. (2003). Trace metal accumulation by red clover grown on sewage sludge amended soils and correlation to Mehlich3 and calcium chloride extractable metals. Soil Sci. 168, 29-38. 

Various methods were applied for determining phosphorus in calcium chloride extracts [143]. 

A test of the stability of the extractable contents of a single soil was carried out for EDTA, acetic acid, ammonium acetate and calcium chloride extracts. With the exception of chromium, the EDTA extractable contents were shown to be stable over 3 year intervals within about 10% for the elements Cd, Cu, Fe, Mn, Ni, Pb and Zn [193]. For acetic acid extracts, one-year changes for Cr, Fe, Mn and Zn were poorer than for EDTA, but for Cd, Cu, Ni and Pb the extracts were reasonably stable. For ammonium acetate and calcium chloride extracts, however, the results, apart from Cd and Ni in ammonium acetate, were useless. These failures in ammonium acetate and calcium chloride were probably related to the fact that the solution concentrations measured were too low for reliable determination by the FAAS and ICP-AES methods used. 

Figure 11.7 Acetic acid extractable content of zinc inmg kg (CRM484) Table 11.19 Indicative values calcium chloride extractable contents...

Wild, A. and Oke, O.L. (1966) Organic phosphate compounds in calcium chloride extracts of soils identification and availability to plants. Journal of Soil Science 1 7, 356-371. 

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