Diffusion of Zinc in Soils as a Function of Applied Zinc, Phosphorus, and Soil pH1
- James R. Melton,
- Samuel K. Mahtab and
- Allen R. Swoboda2
Self-diffusion coefficients, D, of 65Zn were determined in two Texas soils. In the Norwood loam, a calcareous soil of pH 8.2, the effect of applied P and Zn on diffusion coefficients was studied. As the applied P was raised from 0 to 240 ppm, the D value obtained at 0 ppm Zn decreased significantly from 11.73 × 10-11 to 8.57 × 10-11 cm2/sec; at 40 ppm Zn, the D value decreased significantly from 28.51 × 10-11 to 16.33 × 10-11 cm2/sec. Zinc diffusion doubled as the applied Zn was increased from 0 to 40 ppm at all levels of applied P. In the Nacogdoches sandy loam, a soil initially of pH 6 but subsequently raised to pH 7.2 and 7.9 by liming, there was little difference between the D values obtained at pH 7.2 and 7.9. When the applied Zn was increased from 0 to 20 ppm, the D value increased from 5.35 × 10-11 to 7.83 × 10-11 cm2/sec at pH 7.2 and from 3.97 × 10-11 to 6.26 × 10-11 cm2/sec at pH 7.9. However, D values obtained at pH 6 were much larger than those obtained at pH 7.2 and 7.9. As the Zn level was raised from 0 to 20 ppm at pH 6, the D value increased from 19.90 × 10-11 to 19.53 × 10-9 cm2/sec. It appears from this study that the effect of Zn and pH on diffusion of Zn is greater than that of applied P.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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