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