A stable-isotope methodology for measurement of soil-applied zinc-fertilizer recovery in durum wheat (Triticum durum)

Abstract

A growth-chamber study was used to develop a zinc stable-isotope (67Zn) tracing technique to directly measure the amount of soil-applied zinc (Zn) granular fertilizer taken up by durum wheat (Triticum durum L.) in four different soil types. The 67Zn-tracer technique was then applied under field conditions at one site to test the ability of the method to measure the crop recovery of soil-applied Zn granular fertilizer (67Zn). The technique was developed by comparing plants treated with nil Zn fertilizer to natural-abundance-Zn-coated fertilizer and 67Zn-coated fertilizer with plant parts analyzed for Zn isotopic composition using inductively coupled plasma-mass spectrometry. Zinc-fertilizer recovery under growth-chamber conditions was inversely related to the concentration of labile Zn in soils, with the plants on the most Zn-deficient soils having the greatest amount of Zn derived from the added fertilizer. Zinc derived from fertilizer ranged from 0.3% (Luvisol) to 0.6% (Solonetz) to 13% (Calcisol) and 18% (Lixisol) for soils with DTPA-extractable Zn of 3.5-0.21 mgkg-1. Across the experiments, fertilizer recovery was measurable but very low (< 1% of added fertilizer being recovered by durum wheat). The recovery of Zn added to the Luvisol was slightly higher in the field than in the glasshouse (but all < 0.1%). Using this stable-isotope technique, it was possible to directly assess the supply of soil-applied Zn fertilizers to crop plants. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.