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Land degradation

20 Feb, 2014 - 00:02 0 Views

The Chronicle

What is land degradation?
LAND degradation is any change in the condition of the land which reduces its productive potential. It is the deterioration in the quality of land, its topsoil, vegetation, and/or water resources, caused usually by excessive or inappropriate exploitation. It is caused by multiple forces, including extreme weather conditions particularly drought and human activities that  degrade the quality of soils affecting food production, livelihoods and the production and provision of other ecosystem goods and services.

Land degradation is a global issue, with serious implications worldwide on biodiversity, eco-safety, poverty eradication, socio-economic stability and sustainable development. The United Nations Convention to Combat Desertification (UNCCD) estimates that 50 million people may be displaced within the next 10 years as a result of desertification, which is a form of land degradation.

Globally 70 percent of all dry lands are already classified as degraded, representing 14 percent of the earth’s land surface area. In Africa 73 percent of agricultural dry land is thought to be degraded and 70 percent of Africa’s 500 million population depends directly on the environment for livelihoods.

An overview of land degradation in Zimbabwe
Zimbabwe has not been spared, from the adverse impacts of land degradation desertification, and drought. It is estimated that 10 percent of its soils are under high risk of erosion due to the nature of soils, which are sodic. These are soils whose sodium (salt) concentration affects the soil structure.  Such areas include the Hwange-Sanyati Biological Corridor and the St Michaels gullies in Mhondoro. The soils break into fine particles and tunnel subsequently collapsing and forming gullies.  Soil erosion carries away an annual average of 1, 6 million tonnes of nitrogen, 15,6 million tonnes of organic matter and 0,24 million tonnes of phosphorus. On this basis, arable lands alone lose 17,8 million tonnes of soil nutrients each year due to land degradation. The chief drivers of this phenomenon in Zimbabwe are erosion from poor land management practices and poor soil structures, veld fires and the propagation of invasive alien species.

What are the major causes of land degradation?
Bio-physical and socio-economic and political factors which include urbanisation; competition for scarce water, unsustainable water management and policies contribute to land degradation. Bio-physical factors include;

  • Soil erosion;
  • Poor farming practices and the absence of conservation works;
  • Build-up of salts in soils;
  • Loss of vegetation cover due to overgrazing, over exploitation and deforestation
  • Invasive alien species-these grow prolifically and threaten indigenous plants and decrease the land’s biological productivity, pushing out indigenous plants, reducing biodiversity, contributing to soil erosion, reducing grazing areas and reducing the capacity of indigenous plants to reproduce;
  • Overuse of irrigation water;
  • Inappropriate use of marginal land and
  • Veld fires.


What is the impact of land degradation?

  • Increased risks of floods and erosion leading to the formation of gullies;
  • Loss of soil fertility leading to poor crop yields;
  • Shortage of local surface water resources;
  • Increased level of salt groundwater;
  • Propagation of invasive species;
  • Loss of vegetation – Vegetation plays a major role in determining the biological composition of the soil. Studies have shown that, in many environments, the rate of erosion and runoff decreases greatly with increased vegetation cover. Unprotected, dry soil surfaces blow away with the wind or are washed away by flash floods, leaving infertile lower soil layers that bake in the sun and become an unproductive hardpan.
  • Sodic soils form an impermeable crust which reduces infiltration resulting in water scarcity.


What are the effects of Land degradation effects on a global scale?
• 2,6 billion people depend directly on agriculture, but 52 percent of the land used for agriculture is moderately or severely affected by soil degradation.
• Land degradation affects 1,5 billion people globally.
• Due to drought and desertification each year 12 million hectares are lost, where 20 million tonnes of grain could have been grown.
• 74 percent of the poor (42 percent of the very and 32 percent of the moderately poor) are directly affected by land degradation globally (UNCCD).

What can be done to reduce land degradation?
Sustainable land management practices
Land degradation can be effectively tackled, solutions are possible, whose key tools lie in strengthened community participation and co-operation at all levels.
• Integrated approaches are needed because short term cannot solve slowly evolving conditions;
• Great value must be placed on local environmental knowledge systems

Bio-physical solutions include
• Water conservation and harvesting
•  erosion reduction
• Grazing management
• Veld fire management
• Sustainable agricultural practices such as contour ploughing, erecting stone walls and grass strips in fields to reduce erosion, crop rotation, no till farming, growing wind breaks, incorporating organic matter back into fields and avoiding the use of chemical fertilisers because they contain salt.

What is EMA doing to contain land degradation?
EMA is implementing projects that will lead to a land degradation neutral Zimbabwe through increased food security, increased soil productivity, eradication of veld fires, and improved quality of wetlands including rivers, increased forestry productivity and improved biodiversity. The Agency is set to up-scale and replicate the Coping with Drought and climate project for communities to adapt in the wake of the negative impacts of droughts and climate change. Wetland protection and utilisation projects are being undertaken in conjunction with the communities in order to restore some degraded wetlands and also for communities to derive a livelihood. The agency has embarked on several initiatives which include but are not limited to engaging farmers, miners and mapping activities meant to quantify the damage and initiating rehabilitation projects in affected communities. One such project is the Hwange-Sanyati Biological Corridor Project where enrichment planting, stabilisation of gullies by planting vetiver grass, construction of stabilisation structures across medium sized gullies, construction of conservation works and the establishment of agro-forestry systems are being done.

Zimbabwe commemorates the world day to combat desertification each year on the 17th of June. During the UNCCD COP 11 in Namibia in 2013, the country also advocated for the establishment of a global platform. Such a global platform allows stakeholders in Desertification Land Degradation and Drought (DLDD) issues to have a non-binding forum to share ideas, insights, experiences and perspectives during observance days. This can be neatly linked to the Africa Environment Day as well as the World Day to Combat Desertification and Drought. There are also legal provisions meant to curb degradation and those found on the wrong side of the law will be prosecuted.

Did you know?
Estimates show that 24 billion tonnes of fertile soils are lost through erosion. (UNCCD   and World Bank, 2013.

QUOTE OF THE WEEK: “Sustainable land use is a prerequisite for lifting billions from poverty, enabling food and nutrition security, and safeguarding water supplies. It is a cornerstone of sustainable development.” – UN Secretary-General Ban Ki-moon.

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