Assessment of copper and zinc status of some soils of Iringa district
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Date
1992
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Publisher
Sokoine University of Agriculture
Abstract
The objectives of this study were to select suitable extractants for determining available copper and zinc in soils of Iringa district and to assess the fertility status of the two nutrients in the district. Two sets, each of ten soils for one element, were selected for glasshouse studies using maize as a test crop. The soils were treated with 0 and 5 kg ha' of either copper or zinc in their respective trials. Three extractants, viz: 0.1M EDTA-(NH.)jCO;, 0.005M DTPA and 0.1NHC1 were tested for their suitability to extract these elements. The concentrations of these elements in maize shoots were also determined. A total of 61 samples were collected from the district and analyzed for copper and zinc using the methods found to be suitable. Copper and zinc application slightly increased dry matter in four and eight soils, respectively, out of the ten soils tested. However, the increase was not statistically significant. The 0.1N HC1 extractant was superior to the other two in extracting zinc but none of the methods was suitable for copper. The tentative critical concentration for zinc was found to be 0.28ppm. Application of either of these elements in the soils, significantly increased their concentration in the plants. The tentative critical 6.30ppm. copper concentration in maize shoots was For zinc, the critical concentration in shoots was not determined because all the values obtained were above critical concentration extractant, range reported elsewhere. zinc concentration Using the 0.1N HC1 in the soil ranged from 0.14 to 27.30 ppm. For zinc, two fertility classes: medium and high were obtained. The proportions of soils which fell in the medium and high zinc fertility classes were 8.20 and 51.80%, respectively.
Description
Dissertation
Keywords
Copper, Zinc, Soils, Iringa district