Application of Diffusion Gradient in Thin Films (DGT) Method for Prediction of Plant Available Zinc and Copper in Soils and Its Comparison with DTPA Method

There are different methods for assessing the bioavailability of micronutrients in soil and water. One of the new techniques in this regard is diffusive gradient in thin films (DGT). This method acts on ion transport in the diffusion layer and absorption in the resin layer. The aim of this study was to evaluate the performance of DGT for soil Zn and Cu determination and to compare it with Zn- and Cu-DTPA measured for the bioavailability of these elements in maize (Zea mays L.). For this purpose, DGT was placed in 10 soils with different properties that had saturated moisture for 24 h. Also, maize cultivation was done in these soils and, finally, the amount of elements absorbed by the plant was compared with the amount of zinc and copper measured by DGT and DTPA methods. The results showed that there was a linear relationship between Zn and Cu changes in the plant and the concentration of these elements in soil measured by DGT. Zn measured by DGT method (CEDGT) had higher correlation with Zn uptake compared to the DTPA method (r2 = 0.8 for DTPA, r2 = 0.82 for CE) and in the 10 different soils, CE represented 82% of the changes related to the plant Zn uptake. In the case of Cu, the correlation between Cu measured by DTPA and its uptake by maize had a correlation coefficient of 0.75, whereas Cu measured by (CEDGT) had r2 = 0.78. The results of this study showed that DGT is relatively more accurate than the DTPA method for predicting uptake of these elements in maize leaves.