Academic journal article European Journal of Sustainable Development

About to Lose All the Soil in Zaka's Ward 5, Zimbabwe: Rewards of Unsustainable Land Use

Academic journal article European Journal of Sustainable Development

About to Lose All the Soil in Zaka's Ward 5, Zimbabwe: Rewards of Unsustainable Land Use

Article excerpt

1.1 Background

Soil is one of the most important natural resources for living things, humans included. Soils however, undergo a very long formation process .In contrast, its depletion through erosion is very rapid .Whitlow (1988) contends that 1 848 000 hectares of land in all agro-ecological regions in Zimbabwe are eroded and an average of 76 tonnes of soil is lost per hectare through soil erosion. Erosion problems are immensely complicated, involving as they do many social, economic, environmental and political factors. In the soil erosion equation, there is an interaction of energy forces (rainfall intensity),resistive forces ( stable soil aggregates) and protective forces (plant cover). Logically where and when protective and resistive forces are low in relation to energy forces as occurs in most communal areas of Zimbabwe, high rates of erosion occur with dire consequences.

Rates of soil formation in Zimbabwe are quite low, somewhere in the order of 400kg per hectare per year (Whitlow 1988). These rates have been generally accepted for a long time but more recent observations indicate that these rates may be exaggerated. These rates were the result of a survey carried out on a specific single soil type in one ecological region, thus their replicable access in a country with high variability in terms of erosive and stabilising factors is questionable.

There is neither question nor denying that soil erosion is taking place. Lai and Singh (1998) observe that unless erosion is stopped, many parts of Africa will suffer food shortages and famines. As the top soil gets removed, there is loss of nutrients which give plants the necessary requirements for proper growth. The shortage of nutrients leads to crop failure even when moisture is available (Piemental et al, 1997). Although soil erosion is a serious threat to food production, there is little, if at all any effort made to compensate nutrient loss and unfavourable physical soil properties that result from the process (Kariaga 2000).

Soil erosion is such a serious problem, so conservation measures should be considered a key part of sustainable development strategies in the country rather than being treated as a token appendage. This should be understood against the background that the two most important factors which contribute to the statistical variation in erosion are soil type and human population. Whitlow (1988) found a correlation between high population density and high rates of erosion. Fragile /poor soils and high population densities have driven many areas into a full ecological disaster. Such a scenario prevails in Zimbabwe's Zaka district, ward 5 home to 4 502 households in agro-ecological region three.

1.2 Theoretical Framework Soil erosion

Soil erosion involves the detachment of soil particles from larger aggregates and their transportation by water or wind from the soil mass (Kariaga, 1999) .There has been widespread and popular portrayal of a variety of causes of this crisis in Africa. However, Kariga (1999) offered useful quantitative simplification stating that soil erosion results from the dynamic interaction of energy of water or wind causing erosion (erosivity), the inherent existence of the soil system to detachment and transport (erodibility) and the protection factor or vegetation. These causes result in an imbalance between weathering and erosion with the latter exceeding the former. This means that its form gets changed from a 'renewable' to a non- renewable resource in the absence of remedial action. Soils, like water, are the cornerstone of life as we know it. We leave in a world where more and more people are relying on increasingly smaller pieces of land. Zimbabwe, with its fixed area of 390 759 km2 has limited land resources (Central Statistical Office [CSO] 1982, 1992, 2002). If we do not understand our land resources and the environment in which they occur, then we cannot manage them and thus we will be heading for disaster. …

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