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| Titel |
Residual effect of natural and synthetic zinc chelates on zinc in a soil solution of a waterlogged acidic soil. Evolution of the pH and redox potential |
| VerfasserIn |
Patricia Almendros, Demetrio Gonzalez, Jose Manuel Alvarez |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052880
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| Zusammenfassung |
| Zinc chelates have been widely used to correct deficiencies in this micronutrient in different
soil types and under different moisture conditions. The aging of the metal in soil could cause
a change in its availability. Over time the most labile forms of Zn could decrease in activity
and extractability and change to more stable forms. Various soil parameters, such as redox
conditions, time, soil type and moisture conditions, affect the aging process and modify
the solubility of the metal. In general, redox conditions influence pH and also the
chemical forms dissolved in the soil solution. Soil pH also affects Zn solubility; at high
pH values, most of the Zn is present in forms that are not bioavailable to plants.
The objective of this study was to determine the changes in Zn over time in a soil
solution in a waterlogged acidic soil to which synthetic and natural chelates were
applied.
An experiment was conducted under controlled laboratory conditions (at 5 times field
capacity) in an acidic soil [Typic Haploxeralf; field capacity, 6.5 g H2O/100 g soil; pHw
(1/2.5, w/v), 6.1; texture USDA, sandy loam, with illite as the predominant clay; oxidizable
organic carbon 0.29%; available P, 2%] under two years of flax crops. Before the first flax
crop, this soil was treated with a natural chelate, Zn-aminelignosulphonate (Zn-AML) and a
synthetic chelate, Zn-ethylenediaminetetraacetate (Zn-EDTA), at different rates of application
[0 (control), 5 and 10 mg Zn kg-1 soil].
The results obtained showed the evolution of concentrations of Zn in soil solution, pH and
redox potential for three experimental times (15, 45 and 75 d after waterlogging conditions)
for each treatment. The zinc in the soil solution showed significant differences between
treatments, but not between the experimental times for each treatment. Zn-EDTA applied at
the rate of 10 mg Zn kg-1 was the treatment that produced the highest Zn concentration in
the soil solution (values ranged from 13 to 14 mg Zn L-1). Zn-EDTA at the lowest rate of
application and Zn-AML at the highest rate produced similar values (ranging between 1.8
and 3.1 mg Zn L-1). The values of Zn in the soil solution with Zn-AML-5 ranged
between 1 and 1.5 mg Zn L-1 and in the control treatment they ranged between 0.4
and 0.5 mg Zn L-1.The pH parameter showed a slight increase over time with the
Zn-EDTA treatments (values ranged between 5.1 and 5.6), though the control and
Zn-AML treatments showed the stability of this parameter over time (values ranged
between 4.9 and 5.3). The Eh parameter ranged between 290 and 390 mV with
a slight decrease over time. The lowest Eh value corresponded to the Zn-EDTA
treatment for each experimental time. In general, pH + pe values [pe=Eh(mV)/59.2]
showed a slight decrease with time (values ranged from 10.4 to 11.7). These values of
pH and Eh corresponded to soils classified as waterlogged or semi-permanently
saturated. Significant statistical correlations were observed between pH and Eh
parameters (r=-0.525, P |
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