Abstract
Concentrated fertilizer solutions for drip irrigated cultures in southern Spain are normally prepared in an acid medium (pH < 1). These solutions are then mixed with highly saline waters and then applied to substrates of high pH. This study was conducted to determine how those changes in pH alter the composition of the chelate fertilizer solutions that carry iron and other micronutrients.
Eight different chelate formulations were prepared at 100 times the concentration required in drip irrigation solutions along with macronutrients (0.2 M HNO3, 0.2 M H3PO4, 1.0 M KNO3 and 0.5 M Ca(NO3)2). These concentrates were then diluted with irrigation waters (32meq L-1 salts). Half of the replicates were adjusted to pH 7.5 and the others to pH 6.0. The solutions were filtered immediately, or after 24 hours, and the pH and micronutrient concentrations were determined.
Formulations containing EDTA as chelating agent for Fe, Mn, Cu and Zn maintained a higher proportion of the Fe in solution than when only Fe was added as FeEDTA but Mn, Cu and Zn as inorganic forms. FeEDDHA was partially dissociated at low pHs. Reformation of the chelate reached 60%–80% of the total EDDHA after 24 hours. Fe polyflavonoid was completely dissociated at pH 7.5. The use of Fe as a mixture of both FeEDTA and FeEDDHA was the treatment that maintained the greatest percentage of Fe in solution. It appears that FeEDTA may be used as a carrier of Fe during the reformation of the FeEDDHA.
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© 1991 Springer Science+Business Media Dordrecht
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Lucena, J.J., Aberasturi, M.A.J.D., Gárate, A. (1991). Stability of chelates in nutrient solutions for drip irrigation. In: Chen, Y., Hadar, Y. (eds) Iron Nutrition and Interactions in Plants. Developments in Plant and Soil Sciences, vol 43. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-3294-7_7
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DOI: https://doi.org/10.1007/978-94-011-3294-7_7
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