Is an adjusted rhizosphere-based method valid for field assessment of metal phytoavailability? Application to non-contaminated soils

Abstract

An adjusted-RHIZO method was the most promising approach for predicting metal phytoavailability to wheat under field conditions. AbstractPreviously recommended rhizosphere-based method (RHIZO) applied to moist rhizosphere soils was integrated with moist bulk soils, and termed adjusted-RHIZO method (A-RHIZO). The A-RHIZO and RHIZO methods were systematically compared with EDTA, DTPA, CaCl 2 and the first step of the Community Bureau of Reference (BCR1) methods for assessing metal phytoavailability under field conditions. Results suggested that moist bulk soils are equally suited or even better than rhizosphere soils to estimate metal phytoavailability. The A-RHIZO method was preferred to other methods for predicting the phytoavailability of Ni, Cu, Zn, Cd, Pb and Mn to wheat roots with correlation coefficients of 0.730 (P < 0.001), 0.854 (P < 0.001), 0.887 (P < 0.001), 0.739 (P < 0.001), 0.725 (P < 0.001) and 0.469 (P < 0.05), respectively. When including soil properties, other extraction methods were also able to predict phytoavailability reasonably well for some metals. Soil pH, organic matter and FeeMn oxide contents, and cation-exchange capacity mostly influenced the extraction and phytoavailability of metals.

Evaluation of single chemical extractants for the prediction of heavy metal uptake by barley in soils amended with polluted sewage sludge

“…Feng et al (2005a, b), in two studies comparing the suitability of LMWOAs and other extractants to predict heavy metal uptake by wheat and barley from rhizosphere soils, also found this extractant to be the best estimator for Cu and Zn (but not for Ni) considering all the soils but also dividing them as function of pH. The ability of this extractant to estimate Cu, Zn and also Ni uptake was proved by Shan et al (2003), Wang et al (2003) and Fang et al (2007). Finally, Vázquez et al (2008) found LMWOAs the best estimator of Cu and Zn uptake by white lupin grown in nine acid-polluted soils.…”

Rhizosphere Concentrations of Zinc and Cadmium in a Metal Contaminated Soil After Repeated Phytoextraction BySedum Plumbizincicola

“…Single extraction procedures are based on the assumption that there is a relationship between the extractable fraction of soil heavy metals and the availability of heavy metals to plants; that is to say, a good correlation indicates that a certain fraction of the total metal is available to plants (Fang et al 2007). Our results indicate that the NH 4 OAc-extractable fraction in moist soil may provide a method to estimate the availability of Zn and Cd to S. plumbizincicola on the basis of linear correlation coefficients.…”

Comparison of EDTA, HCl and sequential extraction procedures, for selected metals (Cu, Mn, Pb, Zn), in soils, riverine and marine sediments

“…Depending on the nature of the reactant used, they fall into three categories (Lebourg et al, 1996;Sutherland, 2002). Firstly, those which employ salts as CaCl 2 or Ca(NO 3 ) 2 (e.g., An and Kampbell, 2003;Fang et al, 2007), in order to leach cations adsorbed onto solid materials, due to permanent structural charges (phyllosilicates, phyllomanganates and sometimes organic matter). Secondly, techniques which employ acid solutions, in order to simulate the effect of an acid input (e.g.…”