Comparison of soil tests to determine micronutrients status in Argentina soils

Abstract

Soil extraction techniques to measure the status of available micronutrients for plants are important in the diagnosis of deficiency or toxicity. Mehlich 3 (M3), EDTA (pH=8.2), DTPA-TEA, and Soltanpour and Schwab (SS) solutions were confronted for their ability to extract simultaneously copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe). Argentinean soils from different taxonomic orders with widely varying properties were investigated. The values obtained showed that DTPA-TEA and SS solutions extracted similar amounts of Zn, Fe, and Mn, while EDTA dissolved comparatively higher amounts of Fe and Mn. Mehlich 3 yielded the highest extractions for the four micronutrients. Soil pH not only affected the extraction of Mn by DTPA-TEA, SS, and EDTA extractions, but also the extraction of Fe by EDTA. The organic carbon affected the determination of Fe and Zn in all cases. The correlations of the different tests for Cu, Zn, Mn, and Fe were significant. The results suggest that for the determination of the bioavailable status of micronutrients, any of the studied tests could be applied using the soil edaphic properties as factors to improve the correlations between them and standardize the methods.

Evaluation of universal extractants for determination of selected micronutrients from soil

“…Therefore, AB-DTPA extractant can replace DTPA extractant for the determination of available Fe in soils of the studied areas. However, high correlation coefficient (r = 0.75) at (p < 0.05) was found between DTPA and Mehlich 3.This is consistent with previous research findings [42].…”

“…The rest of the methods were also significantly correlated with each other and this is in line with several previous findings [42,43]. Therefore, AB-DTPA extractant can be considered as suitable extractant for the determination of available Cu from soil.…”

“…This is possibly due to the chelating effect of EDTA which reduces the activity of the element in soil solution by complexation of the available ions and promoting further dissolution of the solid labile forms of the Mn. In line with these, Lindsay and Norvell [10], Sims and Johnson [12] and Garcia et al [42] reported that Chelating agents, alone or combined with other solutions, and varying in concentration and pH level, have been used to estimate available Mn. Similarly, Fisseha [19] found EDTA (pH 8.2) extracting comparatively higher amounts of Mn than DTPA (pH 7.3) extractant.…”

The usefulness of Mehlich 3 and 1 M HCl extractant to assess copper deficiency in soil for environmental monitoring purpose / Przydatność ekstrahentów Mehlich 3 i 1 M HCl do oceny niedoborów miedzi w glebie pod kątem monitoringu środowiska

“…A low pH of Mehlich 3 causes transfer of copper ions from the soil to extraction solution. These ions are then complexed by the EDTA molecules contained in this solution [Fonseca et al 2010, Garcia et al 1997. The ability of copper to create chelate complexes has been confirmed by the studies of other authors [Karczewska 2002].…”

“…Assuming that the level of copper concentration in the plant tissue mostly provides information on the availability of this element in soil [Brun et al 2001, Garcia et al 1997, Menzies et al 2007, Sarto et al 2011, Pearson correlation coefficients between soil Cu and plant Cu, as well as between soil Cu and wheat grain yield, were determined (Table 3). In the case of B and C soils, there was a stronger relationship between plant Cu and soil Cu for Mehlich 3 compared with 1 M HCl.…”