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International Journal of Soil Science
  Year: 2012 | Volume: 7 | Issue: 2 | Page No.: 51-60
DOI: 10.3923/ijss.2012.51.60
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The Distribution of Zinc Fractions in Surface Samples of Selected Agricultural Soils of Zambia

Meki Chirwa and Olusegun A. Yerokun

Soil parent material, pedo-chemical transformations and anthropogenic interventions play important roles in the distribution of zinc (Zn) into its various forms in the soil and ultimately, its bio-availability for plant uptake. Therefore knowledge of the soil Zn forms is useful for its management. This study defined five mechanistic Zn pools in 11 cultivated agricultural soils of Zambian and their uncultivated pairs. A batch extraction scheme was used to estimate exchangeable (Ex-Zn), carbonate (CO3-Zn), organic (Org-Zn), sesquioxide (Ox-Zn) and residual (Res-Zn) Zn pools in each soil. Total Zn was calculated as a sum of the pools and it ranged from 13.11 to 108.02 mg kg-1 with an average of 52.26 mg kg-1. The distribution of Zn in the soils on the basis of average concentrations was in the order 22.99 mg kg-1 Ox-Zn (44%)>14.97 mg kg-1 Res-Zn (29%)>7.51 mg kg-1 CO3-Zn (14%)>4.81 mg kg-1 Org-Zn (9%)>1.98 mg kg-1 Ex-Zn (4%). Cultivation depressed Tot-Zn and Ex-Zn concentrations in several of the soils. Correlation analysis (n = 44) showed that Tot-Zn increased along with soil clay content (r = 0.50, p = 0.03) as well as soil Cation Exchange Capacity (CEC) (r = 0.60; p = 0.007), CO3-Zn increased with CEC (r = 0.68, p = 0.001) and Res-Zn increased with soil clay content (r = 0.53; p = 0.02). The fact that the chemistry of Zn in this set of soils appears to be dominated by the more stable fractions offers an explanation for the common notion held that majority of Zambian soils have low soil Zn test levels which accounts for low Zn bio-availability.
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How to cite this article:

Meki Chirwa and Olusegun A. Yerokun, 2012. The Distribution of Zinc Fractions in Surface Samples of Selected Agricultural Soils of Zambia. International Journal of Soil Science, 7: 51-60.

DOI: 10.3923/ijss.2012.51.60






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