Assessment of micronutrient extractants from soils of Paraná, Brazil

Abstract

SUMMARYIn Brazil, plant-available micronutrients in the soil can be determined by several chemical extractants, the most common of which are dilute acid and chelating solutions. The purpose of this study was to assess the extractants 0.1 mol L -1 HCl, Mehlich-1, Mehlich-3 and DTPA for analysis of the micronutrients Cu, Zn, Fe, and Mn in soils from the state of Paraná. In samples from 12 soils (0-20 cm layer), wheat was planted (Triticum aestivum), grown for 42 days after emergence, and then bean (Phaseolus vulgaris) for 38 days. At the end of each planting period, the soil was sampled again. All extractants tested to assess the availability of Cu, Zn, Fe, and Mn correlated with each other. The efficiency of the extractants HCl, Mehlich-3 and DTPA in assessing plant-available Cu was similar, unlike Mehlich-1, which proved less efficient. The extractants HCl, Mehlich-1 and Mehlich-3 were less efficient in estimating plant-available Zn and Fe, and the most indicated extractant is DTPA. The efficiency of the extractants HCl, Mehlich-1, Mehlich-3 and DTPA in assessing plant-available Mn in soils from Paraná was similar.Index terms: soil analysis, correlation, copper, zinc, iron, manganese.

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

“…The high correlation of soil Cu extracted by Mehlich 3 with plant Cu has been confirmed by many authors [Khan et al 2005, Walworth et al 1992. A strong correlation (0.85, α < 0.01) between Cu in tissues of winter wheat and Cu extracted from soil by Mehlich 3 was also indicated by Sarto [2011]. For soil A, and for A+B+C in opposite to soils B and C better results were obtained for 1 M HCl (Table 3).…”

“…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.…”

“…This tendency is confirmed in the literature. Sarto et al [2011] stated after Silva et al [2003] that the increase in clay fraction and soil organic matter caused an increase in the value of Pearson coefficient for the relationship between soil Cu extracted by Mehlich 3 and plant Cu. Different usefulness of the studied soil tests for different soil types was the reason for obtaining lowest correlation coefficients for all three soils together (A+B+C).…”

“…It should be characterized by appropriate strength, mimicking the action of plant root exudates and extract only phytoavailable forms of elements. The efficiency of the extractant is best shown by correlation of the extracted quantities of elements from the soil and their quantities in plants [Brun et al 2000, Rodriguez and Ramirez 2005, Sarto et al 2011.…”

“…The advantage of this extractant is a high correlation between the content of elements in the soil and in the plants grown on this soil [Khan et al 2005, Walworth et al 1992, Sarto et al 2011. The use of Mehlich 3 reduces the time and costs of the performed analyses, because it is a multielement extractant for all macro-and micronutrients.…”