To combat desertification it is necessary to restore and fertilize the land.
Nutritive elements such as nitrogen, phosphorus, calcium, magnesium etc. in the soil are necessary for plants to grow.
When the soil has lost all its nutritive elements or a part of its constituents (removed by wind or water) it is said to be degraded or exhausted and its productivity diminishes as a consequence. It can also accumulate such toxic elements as salt that need to be eliminated.
As these elements become exhausted through intensive
agriculture it becomes necesssary to re-establish soil fertility either
by using synthetic fertilizers or by preparing much cheaper compost.
It is principally prepared from plant waste: manure, agricultural trimmings
(straw), and biological household waste. Water hyacinths, though harmful
in rivers, can be tranformed into fertile matter that supplies nutritive
elements to the soil as compost.
After several weeks in a pit, and with the heat and humidity, humus is produced. It can then be spread among the crops and used to prepare the soil before seedlings are planted. The soil regenerated with organic matter in this way will produce more fruitful harvests. The restructuring of the soil is a very effective and particularly sustainable way to maintain soil fertility (See cartoon: The School Where the Magic Tree Grows).
The presence of livestock could also be exploited to enrich the soil. By consuming crop leftovers (millet, maize) the animals return nutritive elements to the soil that enriches it with nitrogenous matter in the form of dung. Dung also restores the capacity of soil to produce a more plentiful harvest. The herd also provides meat and milk. In this way, farmers and cattle rearers can help each other.
Some simple mechanical means to alleviate the effects of wind that prevent the displacement of sand and dust, include:
Reforestation requires the creation of nurseries to nurture young plants among local species selected for their rapid growth and adaptation to the harsh climate. Reforestation is a long-term action since tree growth is slow. Fortunately, trees have a long life cycle so the investment is generally viable. (See the case studies from Chile and India).
Trees play several roles:
However, they should be used in a sustainable way, trees should be replaced as they are being cut down. Alternative energy sources could also be explored to ease the pressure on tree logging (See Unit 19).
Relentless tree logging.
Make a poster demonstrating
the dos and don’ts of combating desertification. Include the best farming practices that contribute to combating desertification as well as the farming techniques that should be avoided. You can paste it to the wall chart.
How does this list compare to the techniques/methods employed in your village/town?
Make a model that represents the vegetation that can be planted locally to combat desertification.
Ask the local farmers which plants are the most useful for combating desertification ie. bamboo plants used to stabilize the land.
(See the case study from Kenya)
With your parents, construct a windbreak from dry grasses to help them protect their crops.
Discuss in class the different roles played by trees.
Explain why it is important to protect them.
What in your view is the principal function of a tree?
Defend your point of view.
Underline the following correct phrases:
• the loss of soil nutrients leads to a drop in productivity (harvests are smaller).
• chemical fertilizers should replace manure whenever possible.
• windbreaks can be made from metal or plastic sheeting.
• tree planting is a short-term action since trees grow rapidly.
• trees have the effect of destroying the soil.
• fallow periods should be sufficiently long to allow the soil to recover.