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THE EVALUATION OF DIFFUSIVE GRADIENTS IN THIN FILMS (DGT) AND CaCI₂ EXTRACTION ON PHOSPHORUS-ZINC INTERACTION IN SUDAN GRASS

OSMAN SONMEZ^1*, GARY PIERZYNSKI², CENGIZ KAYA³ AND SALIH AYDEMIR³

Abstract: Diffusive gradients in thin films (DGT) has been used for the assessment of Zn availability and offers some advantages over routine batch extractions of soil samples.   To evaluate the effectiveness of DGT compared with CaCl₂-extraction to P additions in Zn contaminated soil, a greenhouse study was established.  Zinc was added at the rate of 0, 150, 300, 600 and 1200mg Zn kg^-1 as ZnSO₄ in order to create various levels of Zn phytoavailability. Soil was amended with KH₂PO₄ at 0, 100 and 200mg P kg^-1.  Increasing application of Zn to soil elevated Zn adsorption by DGT, plant Zn concentrations, CaCl₂ extractable and water-soluble Zn and decreased soil bioavailable P and pH. Internal plant concentrations and CaCl₂-extraction were influenced by P additions, whereas DGT Zn concentrations were not affected. Phosphorus application decreased plant Zn concentrations and increased plant biomass yields.

Key words: DGT, Phosphorus, Zinc, Metal bioavailability, Metal uptake.

¹Department of Soil Science and Plant Nutrition, Faculty of Agriculture, Erciyes University, Kayseri 38039, Turkey

²Department of Agronomy, Throckmorton Plant Sciences Center, Kansas State University, Manhattan, Kansas 66506-5501, USA

³Department of Soil Science, Faculty of Agriculture, Harran University, Sanlıurfa 63200, Turkey

^*Corresponding author’s e-mails: osmansonmez@erciyes.edu.tr. ; osharran@yahoo.com