Methods for estimating soil iron availability to chlorotic peach trees

Abstract

Available iron (Fe) determination in calcareous soils by using commonly accepted method (DTPA + CaCl2 + TEA) is not descriptive in estimating Fe concentration in plants. Therefore, this study was conducted to select appropriate methods for the evaluation of available Fe status in peaches grown in alkaline soils. Leaves and soil samples were collected from a peach orchard with trees showing various chlorosis levels. Twelve extraction methods were applied to the soils to determine the available Fe content of the soils. Total and active Fe concentrations in leaves were assayed, and a relationship was investigated among chlorosis levels, total and active Fe in the leaves, and Fe assayed by the various methods to select the most representative method. The methods of 0.05 M EDTA (pH 7.0), 1 M NH4HCO3 + 0.005 M DTPA (pH 7.6), 0.05 M HCl + 0.012 M H2SO4 and active Fe were well correlated to visual chlorosis ratings, total and active Fe in the leaves and factors affecting Fe availability in the soils compared with other methods. Therefore, these four methods should be used for determination of available Fe status in peaches grown in different soils.