Faidherbia - Africa's fertiliser factory

The nitrogen-fixing acacia tree, Faidherbia albida, boosts  soil fertility

Lying in the heart of Africa, Malawi is well known for its export of tea,  sugar and tobacco, which take up much of its arable land. But the country's  biggest agricultural export originates not from these commercial plantations;  nor is it an intended one. It is soil, eroded from the fields of smallholder  farms that support 80 per cent of Malawi's population.


Loss of Malawi's valuable soil can be seen by the extensive gully erosion  visible on hillside plots, where heavy rains have breached planting ridges, and  the rivers flow muddy brown with silt. As a result of declining fertility and  degraded soil, crops often fail or yields are low and farmers struggle to feed  their families. With the impact of global warming, farmers have "never been less  prepared," asserts Peter Aagaard, director of the Conservation Farming Unit  (CFU), which is based in Zambia but has an increasing following in Malawi.


The solution, according to the CFU, lies in minimising soil disturbance,  while boosting fertility through planting of the nitrogen-fixing acacia tree,  Faidherbia albida. This is in marked contrast to the  traditional practice of land preparation in Malawi, where splitting and  reforming ridges moves an estimated 700 million tons of soil every year, and  results in high labour costs as well as water logging and soil degradation.  Instead, farmers are being encouraged to dig small planting pits, a minimum  tillage technique which disturbs only ten per cent of the soil. With funding  from the Norwegian Government, the CFU is also training farmers to practice crop  rotation, and to protect their soils by leaving crop residues on the ground  instead of burning them.

References:
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New Agriculturist Article:  Faidherbia - Africa's fertiliser  factory