Browsing by Author "Kamasho, Josephath Aiwinia"

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    Copper and Zinc Status of some volcanic ash soils in the Mbeya district
    (University of Dar es salaam, 1980) Kamasho, Josephath Aiwinia
    The aim of this project was to prepare the available Cu and Zn fertility maps for the soils of the Mbeya District. Before reaching this stage, an investigation was carried out to select a suitable extractant for these two nutrient elements. Critical soil-test values and limits for Cu and Zn fertility categories to be used for demarcating the area were identified. Attempts were also made to identify critical plant tissue content of Cu and Zn fertilisation on soils of different fertility in the district. Among the three extractants, 0.1N HC1, 0.05M EDTA and DTPA, evaluated for their suitability for assessing Cu and Zn availability in the soils of the Mbeya District, DTPA was most suitable. The tentative critical soil-test values below which wheat may respond to Cu and Zn fertilisation were 0.7 ppm Cu and 3.5 ppm zn as extracted by DTPA. Although somewhat inferior, 0.05M EDTA may be considered as an alternative to DTPA with tentative critical soil-test value of 1.0 ppm Cu and 11.0 ppm Zn. Based on the DTPA-extractable Cu and Zn contents, and pattern of distribution of relative yields with respect to soil-test values, three fertility categories were identified as follows: