Browsing by Author "Mkangwa, Chaboba Zaid"

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Assessment of copper and zinc status of some soils of Iringa district
(Sokoine University of Agriculture, 1992) Mkangwa, Chaboba Zaid
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.
Influence of minjingu phosphate rock application on tephrosia vogellie fallow productivity and subsequent maize response on a ferralsol in morogoro,Tanzania
(Sokoine University of Agriculture, 2004) Mkangwa, Chaboba Zaid
The objectives of this study were to quantify the response of /'. vogelii fallow to Minjingu Phosphate Rock (MPR) application at establishment on quantity and quality of biomass produced. P availability, total inorganic-N. maize yields, and pH and Ca changes on an acidic. I’ deficient Ferralsol. The data w'ere collected from pot. incubation and field experiments. The pot studies were used to assess response of T. vogelii seedlings to MPR. P and Ca applications, and that of maize to 7'. vogehi biomass and MPR applications Incubation experiments were used to evaluate the influence of MPR application on decomposition of 7'. vogelii biomass and N release. and the effects of combined application of MPR and T. vogelii biomass on Pi-P. The field experiments were used to evaluate the effects of MPR application at fallow establishment on /' vogelii performance, maize response to fallow' biomass and MPR applications, and to residual MPR and fallow biomass and fresh biomass applications. In soil of pH 5.9. the quantity, quality and Nz-fixing capacity of T vogelii seedlings were significantly improved relative to pH 5.0. Application of MPR improved these parameters at both values of soil reaction. The quality and quantity of 7'. vogelii biomass depended on P application. Combined application of T. vogelii biomass and MPR significantly increased maize DM yield in the pot and field studies, but depressed Pi-P in the incubation study. Decomposition of T. vogelii biomass was significantly increased only in the first 28 days by MPR application and was not effected thereafter. Minjingu PR application at fallow establishment significantly increased the quantity and quality of T. vogelii biomass, total inorganic- N and Pi-P in the fallow's. Subsequent to fallows, application of T. vogelii fallow'Ill biomass or combined with MPR significantly increased total inorganic-N. The Pi-P. earleaf N and P concentrations, soil pH. exchangeable Ca and maize yields were significantly increased by application of MPR at fallow establishment and by combined MPR with fallow biomass It is concluded that application of MPR on a strongly acid P deficient Ferralsol improves the quantity and quality of T. vogelii fallows and subsequent maize yields