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Title: CharacteriZation of vermiculites from the Mozambique belt of Tanzania for agricultural applications
Author: Marwa, Ernest Melkiory Magesa
ISNI:       0000 0004 2682 8463
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2009
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This research was carried out with the main objective of assessing the suitability of Tanzanian vermiculites as soil improvers for crop production through characterization. The research involved five samples from Tanzania and one from South Africa, which was included for comparison purposes. The results show that not all samples are vermiculites, some are hydrobiotites. Analysis shows that none of them contain hazardous accessory minerals. The samples have high cation exchange capacities (CEC) and, thus, they are suitable as soil improvers with ability to retain plant nutrients form leaching. Some have elevated concentrations of Cr and Ni, but the metals are insignificantly plant-available and do not inhibit the uptake of essential plant nutrients. Heating vermiculites above 600 °C should be avoided as it reduces the CEC by more than 90%, and makes some of the exfoliated products strongly alkaline and, thus, unfavourable for crop production. The Tanzanian vermiculites can retain plant-available water, but their ability is less than vermiculite from South Africa. The P in the vermiculites is extractable and extractability increases on heating to 200-400 °C. Application of vermiculites to the soil significantly enhanced the retention and fertilization of P. Nitrogen and K were less retained. Maize vegetative growth, dry matter yield, and nutrient uptake were significantly enhanced by amending the soil with vermiculites. Pre-heated vermiculite at 600 °C performed better than unheated vermiculite and inhibited the fixation of the applied K and N. Thus, the Tanzanian vermiculites are suitable for use as soil improvers for crop production. However, more field trials are recommended on other types of soils and crops other than sand and maize used in this research.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available