Browsing by Author "Marwa, E. M."
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Item The effect of parent material and topography on soil morphology, mineralogy, and classification of some soil profiles on a selected transect in Morogoro district, Tanzania(SADC-ICART Project, 2010) Kaaya, A. K.; Sorensen, R.; Marwa, E. M.; Msaky, J. J. T.Soil associations on a transect west of Mindu mountains in Morogoro District were studied in order to establish the effect of parent material and topography on soil morphology and mineralogy of some soil profiles in Morogoro District based on their catenary relationships.Eight soil profiles were described, sampled, and analyzed in the laboratory. From the upper to the lower parts of the landscape, the profiles included: well drained soils formed from quartz rich muscovite biotite gneisses and migmatites; well drained soils weathered from hornblende biotite gneiss; and imperfectly drained ‘mbuga’ soils developed from old and recent fluvial materials on the Wami-Mkata plains. The study revealed that changes in soil properties along the transect were abrupt particularly the degree of soil profile development, soil depth, soil colour, clay content, soil mineralogy, cation exchange characteristics, and accumulations of carbonates or Fe-oxides. This demonstrates clearly that the soil properties along this transect are mainly controlled by the nature of the parent materials and their position on the landscape. Soils developed from the quartz rich muscovite biotite gneisses and migmatites in the upper parts of the landscape are moderately weathered, shalloItem Liming and sulfur amendments improve growth and yields of maize in Rubona Ultisol and Nyamifumba Oxisol(Taylor & Francis, 2015-07-27) Sirikare, N. S.; Marwa, E. M.; Semu, E.; Naramabuye, F. X.Aluminum toxicity is a major limitation to crop production on highly weathered and leached soils in Rwanda. Moreover, sulfur though widely deficient in Rwanda acidic soils has received little attention by soil fertility researchers. A field experiment on maize response and soil nutrients status to liming materials of travertines at 3.4 t ha-I , ash wood 1.2 t ha-I of CaO equivalent and sulfur at 10 kg ha-1 combined with NPK at 80, 60, and 45 kg ha-I respectively was conducted in Rubona Ultisol and Nyamifumba Oxisol. Results revealed that travertine and wood ash increased the soil pH from 4.7 to 5.8 or higher and decreased exchangeable Al3+ and H+ to near 0 cmolc kg-1. Soil nutrients generally increased to high or medium ranges for crop production. Leaf dry biomass, plant height and maize grain yields were significantly higher in Rubona Ultisol than in Nyamifumba Oxisol. Plots that received wood ash, with NPKS or with NPK, generally had higher maize yields, followed by those which received travertines and NPKS or NPK which had maize growth response as compared to the control plots which received NPK only. Thereby, a combination of wood ash with NPKS or NPK, travertines with NPKS was found to neutralize soil aluminum toxicity, increase soil nutrients status to required levels for plant growth and increase maize yields significantly.