The effect of humic acid and Na2EDDHA on the uptake of Cu, Fe, and Zn by barley in sand culture

Abstract

Humic acid affected nutrient uptake differently in sand culture. It generally increased Cu uptake, slightly, though insignificantly, increased Fe uptake and practically had no effect on Zn uptake. Such results agree fairly well with the relative stability of humic acid with these metals. When humic acid was added to sand culture at increasing concentration of the metal, it considerably increased dry weight, Cu uptake and Cu concentration through decreasing its toxicity to plant. With Fe, however, humic acid and Na<inf>2</inf>EDDHA slightly increased Fe uptake at lower Fe concentration (30 ppm) but significantly reduced both Fe uptake and Fe concentration in plant at higher concentration of Fe compared to the control treatment. Humic acid reduced Zn uptake and Zn concentration in plant at concentrations of 0.5-1.5 ppm Zn, and guarded against Zn toxicity which developed at higher concentration of Zn when no humic acid was added. © 1978 Martinus Nijhoff.