Browsing by Author "Mhosole, Michael Silyamgoda Chambasingo"

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    Assessment of zinc status in soils and tea response to added zinc in selected estates in Mufindi district,Tanzania
    (Sokoine University of Agriculture, 1995) Mhosole, Michael Silyamgoda Chambasingo
    A study was conducted in Mufindi district to determine the status application of zinc Soil and the of response tea to zinc zinc status was assessed by using a sequential extraction procedure and DTPA extractant. Leaf zinc status was assessed by using procedure. Five levels of zinc: kg Zn/ha as zinc oxide a wet oxidation 0, 2.5, 5.0, 7.5 and 10 (80% zinc) applied both on the foliage and on soil were used to test the effect of zinc application on tea yield. The zinc fractionation study indicated that of the total soil zinc, 4.2% was exchangeable, 1.1% was associated with carbonates z 18.1% with organic matterr oxides and 49.9% with the residual 23.5% with fraction.Thus the largest proportion of zinc was associated with the residual fraction. The DTPA extractable zinc ranged from 0.70-3.46 and from 0.70-5.20 mg/kg in the cultivated and virgin soilsz respectively. Leaf zinc concentration ranged from 11.76-32.64 mg/kg. This range indicated that some estates were deficient in zinc. Foliar application of zinc at a rate of 2.5 kg Zn/ha significantly (P<0.05) increased tea yields by upto 32%. yields slightly. Soil application of zinc decreased The decrease was probably due to unfavourable interaction between zinc and other cations,especially magnesium.The critical zinc deficiency level was estimated to be 1.7 mg DTPA zinc/kg. Soils with DTPA zinc of less than 1・ 7 mg/kg are likely to respond to zinc application. More than half (55%) of the estates covered in this study are deficient in zinc. Foliar application of zinc oxide at a rate of 2.5 kg deficiency Zn/ha is recommended to correct zinc