Soil scientist John Reganold says,“One of the major problems is that the soils are fairly poor in most of the regions.So how do you grow food on poor soils?There have to be food
production systems that can build the soil and improve the
yield.”
Mr Reganold says poor soil may have resulted from years
of weathering that washed away many nutrients.He says some
farmers may have done more harm than good.
“They have been actually using farming practices where
they’re not putting in organic matter.They’re not putting in
fertilizers.They can’t afford those things.And it just runs the
soil down.So they’re worsening the situation.”
The scientist says the word perenniation defines three
systems that are already used in Africa.The oldest of the three
is called evergreen agriculture.This is where farmers plant trees with their crops.Farmers in Africa have been doing this for sixty years,but it seems to be growing in popularity.
The method is gaining widespread use in countries such as Niger,Burkina Faso,Malawi and Zambia.The trees are planted among maize (玉米),millet or sorghum crops.They not only add nitrogen (氮) to the soil through their roots,but also through their leaves when they fall off and break down.At other times of the year,the trees can protect plants from strong sunlight.
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