College of Agricultural Sciences and Fisheries Technology

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Browsing College of Agricultural Sciences and Fisheries Technology by Subject "Afforestation"

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    Evaluation of climate and soil properties in parts of Dodoma district, Tanzania in
    (University of Dar es Salaam, 1979) Nshubemuki, Ladslaus
    Information on climate and soil in Dodoma district, Tanzania is coordinated and interpreted in terms of potential for afforestation and village afforestation. Dodoma district covers about 16,600km2, and is dominated by pre-Cambrian metamorphic rocks with extensive granite intrusions. Altitude and slope are generally less than 1,320m and 10percent respectively. The climate is send-arid. Hence annual rainfall is slightly over 500mm, with a five to six months dry season. Climatic analysis concentrated on rainfall from 16 stations. Ten day intervals were used as a basis for evaluating short term moisture availability fluctuations. Analysis concentrated on rainy days, the distribution of rain, its probability of occurrence both in the rainy season and after planting trees in the field. Aerial photographs and geological and topographical map were used in locating soil sampling sites on six traverses in a sampling area of 124km2. Soils were sampled at 37 places. Rainfall is the main limiting factor to tree growth. There is an average of two to three rain days per 10day period during the rainy season but variability is high and rainfall unreliable for individual decades. The PH, electrical conductivity and available water values generally show increases down the slope, demonstrating a need to consider alkalinity and salinity tolerance, and general water requirements when species are to be chosen for afforestation in the area. Pairly homogeneous afforestation units (i.e. forestry land use classification units) were recognized by reference to serial photographs, geological and topographical maps, soil analysis and rainfall data. Water balance calculations indicated that though most of the forestry land use catagories oftem may not reach field capacity there is a significant relationship between total monthly rainfall and run-off (r=0.93). the need for soil water conservation is emphasized. From planting experience to data Azadirachta indica, Cassia simmean Casuarina equisetifolia, Ducalyptus camaldulensis, E.citriodors, E.tereticornis variety Zanzibar “C” Chelina arborea, Grevillea robusta and sygygium cumini, appear promising trees to grow in the area. It is concluded that successful village afforestation programs would diversity the district’s economy because some species (e.g. Acacia albida) have agro-forestry potential while others (e.g. melia azedarach) are suitable for paper production or (e.g.prosopis chilensis) say promote beekeeping. It is suggested that integrated planning should be used to cope with the direct and indirect effects of the afforestation programs.
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    A study of accasia albida del. with reference to community afforestation
    (University of Dar es Salaam, 1983) Kiriinya, C. K
    Acacia albida Del. is a large nitrogen fixing leguminous tree typical of riverine sites in semi arid areas throughout Africa. This study is concerned with evaluating its potential for agroforestry. Laboratory, nursery and field experiments were carried out at Morogoro, Tanzania, to investigate seed pretreatment procedures, nursery growth and establishment, early field performance, nitrogen fixation rates and initial relationships with intercropped food crops. The most effective seed pretreatment was concentrated sulphuric acid for 20 - 30 minutes which gave 97 -100% germ nat on in 21 days while the least effective pre-treatment eras scorching which resulted in no germination over the same time. In the nursery, survival percentage was 98% and shoot growth was rapid: plant were 28.2 ± 6.7 cm tall, with mean biomass 4.6 ± 3,.6 g dry weight, after 12 weeks. Size at outlanting had no effect on survival, in the field: the mean survival percentage after months was 92% Large (43 cm}, medium (34 cm) and total increment of 10.4, 11.1 and 10.4 cm, respectively, over 6 months. Survival was affected by pre-out planting time in the nursery. The youngest (75 days higher mortality (13%) than older seedlings (11%) but the difference was not statistically significant. The mean height increment was 10.6 + 0.5cm and did not differ significantly among the different ages. Intercropping with maize was found not to affect young A, albida trees in height growth or root collar area increment the six months period. Conversely, maize yield was not affected by the presence of young A. Albida trees. Nitrogen fixation was detected in both nursery stock and field stock. The mean fixation rate recorded per gram dry weight of nodules in the nursery was 21 +11.6 n molC2 H4 mg -1 h-1 while in the field the rate was 10±5.5 n mol C2 H4 mg -1 h-1. Results are interpreted and discussed with respect to published information on the species and its use at Morogoro since 1980 in agroforestry experiments. It is concluded that A. albida has high potential for agro-forestry in semi-arid areas particularly since it is in such areas that pastoralism has major significance and is, in settled societies, complemented by rainy season food crop cultivation. Acacia albida is more compatible with this type of tradition than any of the better known agroforestry trees and is also better adapted to the conditions involved than many others.